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Research Notes: Hypothyroidism in Prader-Willi SyndromeClin Endocrinol (Oxf). 2007 Sep. Background. Prader-Willi syndrome (PWS) is a neurogenetic disorder characterized by muscular hypotonia, psychomotor delay, obesity and short stature. Several endocrine abnormalities have been described, including GH deficiency and hypogonadotrophic hypogonadism. Published data on thyroid hormone levels in PWS children are very limited. Objective To evaluate thyroid function in children with PWS, before and during GH treatment. Design/patients. At baseline, serum levels of T4, free T4 (fT4), T3, reverse T3 (rT3) and TSH were assessed in 75 PWS children. After 1 year, assessments were repeated in 57 of the them. These children participated in a randomized study with two groups: group A (n = 34) treated with 1 mg GH/m(2)/day and group B (n = 23) as controls. Results. Median age (interquartile range, IQR) of the total group at baseline was 4.7 (2.7-7.6) years. Median (IQR) TSH level was -0.1 SDS (-0.5 to 0.5), T4 level -0.6 SDS (-1.7 to 0.0) and fT4 level -0.8 SDS (-1.3 to -0.3), the latter two being significantly lower than 0 SDS. T3 level, at 0.3 SDS (-0.3 to 0.9), was significantly higher than 0 SDS. After 1 year of GH treatment, fT4 decreased significantly from -0.8 SDS (-1.5 to -0.2) to -1.4 SDS (-1.6 to -0.7), compared to no change in untreated PWS children. However, T3 did not change, at 0.3 SDS (-0.1 to 0.8). Conclusions. We found normal fT4 levels in most PWS children. During GH treatment, fT4 decreased significantly to low-normal levels. TSH levels remained normal. T3 levels were relatively high or normal, both before and during GH treatment, indicating that PWS children have increased T4 to T3 conversion. Am J Med Genet A. 2007 Apr 12. Prader-Willi syndrome (PWS) is a well-defined syndrome of childhood-obesity which can serve as a model for investigating early onset childhood obesity. Many of the clinical features of PWS (e.g., hyperphagia, hypogonadotropic hypogonadism, growth hormone deficiency) are hypothesized to be due to abnormalities of the hypothalamus and/or pituitary gland. Children who become severely obese very early in life (i.e., before age 4 years) may also have a genetic etiology of their obesity, perhaps with associated neuroendocrine and hypothalamo-pituitary defects, as infants and very young children have limited access to environmental factors that contribute to obesity. We hypothesized that morphologic abnormalities of the pituitary gland would be seen in both individuals with PWS and other subjects with early onset morbid obesity (EMO). This case-control study included individuals with PWS (n = 27, age 3 months to 39 years), patients with EMO of unknown etiology (n = 16, age 4-22 years; defined as body mass index greater than the 97th centile for age before age 4 years), and normal weight siblings (n = 25, age 7 months to 43 years) from both groups. Participants had 3-dimensional magnetic resonance imaging to evaluate the pituitary gland, a complete history and physical examination, and measurement of basal pituitary hormones. Subjects with PWS and EMO had a higher prevalence of pituitary morphological abnormalities than did control subjects (74% PWS, 69% EMO, 8% controls; P < 0.001). Anterior pituitary hormone deficiencies were universal in individuals with PWS (low IGF-1 in 100%, P < 0.001 PWS vs. controls; central hypothyroidism in 19%, P = 0.052, and hypoplastic genitalia or hypogonadotropic hypogonadism in 100%, P < 0.001), and was often seen in individuals with EMO (6%, P = 0.89 vs. control, 31%, P = 0.002, and 25%, P = 0.018, respectively). The presence of a hypoplastic pituitary gland appeared to correlate with the presence of anterior pituitary hormone deficiencies in individuals with EMO, but no correlation was apparent in individuals with PWS. In conclusion, the high frequency of both morphological and hormonal abnormalities of the pituitary gland in both individuals with PWS and EMO suggests that abnormalities in the hypothalamo-pituitary axis are features not only of PWS, but also frequently of EMO of unknown etiology. Am J Med Genet A. 2007 Mar 1. No abstract available. J Pediatr Endocrinol Metab. 2002 Jan. We report a 1 year-old female patient with severe hypotonia who has congenital hypothyroidism and Prader-Willi syndrome (PWS). At birth she was found to have congenital hypothyroidism caused by an ectopic sublingual thyroid gland and was commenced on thyroid replacement therapy. She continued to have severe motor delay and therefore further diagnostic evaluation was performed. PWS was confirmed by DNA and fluorescence in situ hybridization (FISH) analysis. This report emphasizes the need to further investigate patients who are found to have congenital hypothyroidism and do not improve adequately on treatment. Am J Perinatol. 1999. We describe a unique case of a newborn with Prader-Willi syndrome who presented with fetal goiter as well as neonatal thyroid abnormalities, marked hypotonia, and thrombocytopenia. These new clinical observations may correlate with the uniparental monodisomy form of inheritance of this genetic condition. Acta Paediatr Suppl. 1997 Nov. Disturbances of the hypothalamic-pituitary-gonadal axis are reviewed in patients with Prader-Willi syndrome, and a brief account is given of thyroid function, adrenal function and glucose metabolism in such patients. Cryptorchidism, hypoplastic external genitalia and delayed or incomplete pubertal development in most patients with Prader-Willi syndrome suggest dysfunction of the hypothalamic-pituitary-gonadal axis. Decreased levels of gonadotrophins, consistent with hypogonadotrophic hypogonadism, have been found in some patients, whereas others appear to have hypergonadotrophic hypogonadism secondary to cryptorchidism and its treatment. Gonadal function is normal in a small number of patients with the syndrome. Although most clinicians agree that cryptorchidism should be corrected in early childhood, in practice the surgery is often not performed. In addition, most patients do not receive sex hormone replacement therapy. It is therefore suggested that more aggressive endocrine treatment strategies for hypogonadism are warranted in both children and adults with Prader-Willi syndrome. Both thyroid function and adrenal function appear to be normal in most patients, and glucose metabolism is similar to that in normal obese individuals. Minerva Pediatr. 1991 Sep. Five children (3 boys and 2 girls) ranging in age form 5-12 years and suffering from Prader-Willi syndrome have been evaluated. In each subject the Authors have examined auxological parameters and the following hormonal values: GH after two pharmacological stimuli tests, gonadotropins after LHRH, TSH and prolactin after TRH, cortisol rhythm, testosterone after hCG in males, thyroid hormones and steroids. The results have shown a height less than 3 degrees centile only in a subjects and ranging from 10 degrees-50 degrees in the others, a weight greater than 97 degrees centile for the height age in all, a low response in GH to both stimuli in two subjects, an increased response to LHRH in FSH in two subjects. All other endocrine evaluations were in the normal range with the exception of insulin that resulted augmented in spite of normal glycaemic values. In conclusion, our data would suggest the existence of an eventual alteration of the hypothalamus-pituitary structures. J Ment Defic Res. 1989 Jun. A case of Prader Willi Syndrome who suffered from hypothyroidism is described. This patient on cytogenetic examination was found to have Mosaic 46,XX/46,XX,del(15)(q11.1q11.2) karyotype. An Esp Pediatr. 1983 Jan. Growth charts of five children with Prader-Labhart-Willi syndrome were examined. Clinical diagnosis was based on usual features of this condition. These included hypotonia in infancy, obesity, mental retardation, short stature, undescended testes in boys and typical physical features. Extensive investigations have failed to reveal pathognomonic abnormalities in this syndrome. Obesity and failure to thrive, beginning in early infancy and increasing with age is a precocious and typical feature. This pattern helps to early diagnosis. Only congenital hypothyroidism could show a similar pattern.
J Neurol Sci. 2007 Jul 23. The incidence and prevalence of autism have increased during the past two decades. Despite comprehensive genetic studies the cause of autism remains unknown. This review emphasizes the potential importance of environmental factors in its causation. Alterations of cortical neuronal migration and cerebellar Purkinje cells have been observed in autism. Neuronal migration, via reelin regulation, requires triiodothyronine (T3) produced by deiodination of thyroxine (T4) by fetal brain deiodinases. Experimental animal models have shown that transient intrauterine deficits of thyroid hormones (as brief as 3 days) result in permanent alterations of cerebral cortical architecture reminiscent of those observed in brains of patients with autism. I postulate that early maternal hypothyroxinemia resulting in low T3 in the fetal brain during the period of neuronal cell migration (weeks 8-12 of pregnancy) may produce morphological brain changes leading to autism. Insufficient dietary iodine intake and a number of environmental antithyroid and goitrogenic agents can affect maternal thyroid function during pregnancy. The most common causes could include inhibition of deiodinases D2 or D3 from maternal ingestion of dietary flavonoids or from antithyroid environmental contaminants. Some plant isoflavonoids have profound effects on thyroid hormones and on the hypothalamus-pituitary axis. Genistein and daidzein from soy (Glycine max) inhibit thyroperoxidase that catalyzes iodination and thyroid hormone biosynthesis. Other plants with hypothyroid effects include pearl millet (Pennisetum glaucum) and fonio millet (Digitaria exilis); thiocyanate is found in Brassicae plants including cabbage, cauliflower, kale, rutabaga, and kohlrabi, as well as in tropical plants such as cassava, lima beans, linseed, bamboo shoots, and sweet potatoes. Tobacco smoke is also a source of thiocyanate. Environmental contaminants interfere with thyroid function including 60% of all herbicides, in particular 2,4-dichlorophenoxyacetic acid (2,4-D), acetochlor, aminotriazole, amitrole, bromoxynil, pendamethalin, mancozeb, and thioureas. Other antithyroid agents include polychlorinated biphenyls (PCBs), perchlorates, mercury, and coal derivatives such as resorcinol, phthalates, and anthracenes. A leading ecological study in Texas has correlated higher rates of autism in school districts affected by large environmental releases of mercury from industrial sources. Mercury is a well known antithyroid substance causing inhibition of deiodinases and thyroid peroxidase. The current surge of autism could be related to transient maternal hypothyroxinemia resulting from dietary and/or environmental exposure to antithyroid agents. Additional multidisciplinary epidemiological studies will be required to confirm this environmental hypothesis of autism. Acta Paediatr. 2007 Mar. AIM: A prospective study was conducted to determine thyroid hormone levels and their relationship to survival in children with septic shock and sepsis. METHODS: We estimated thyroid hormone levels (T3, T4, TSH, fT3 and fT4) in children with septic shock and compared with those in children with sepsis. RESULTS: Twenty-four children (13 boys) with septic shock and 25 children (14 boys) with sepsis were enrolled. The median T3, T4, fT3, fT4 and TSH (95% confidence interval) were 40 (40-40.23) ng/dL, 4.45 (1.9-6.03) microg/dL, 1.85 (1.2-2.37) pg/mL, 0.77 (0.57-0.95) ng/dL, 0.51 (0.26-1.15) microIU/mL, respectively in children with septic shock group compared with 130 (98.28-163.48) ng/dL, 9.3 (7.66-10.63) microg/dL, 3.2 (3-4.27) pg/mL, 1.3 (1.1-1.4) ng/dL, 2.85 (1.07-3.61) microIU/mL, respectively, in children with sepsis. Children with septic shock who died (n = 12) had higher TSH levels compared to those who survived (p = 0.04). There was no difference in hormone levels between children with catecholamine responsive and catecholamine resistant septic shock. CONCLUSION: Children with septic shock had lower levels of T3, T4, fT3, fT4 and TSH compared to those with sepsis. Findings of our study suggest that derangement of thyroid functions in children is not an important factor contributing to the severity of septic shock.
Clin Endocrinol (Oxf). 2007 Jan. BACKGROUND: The effect of GH replacement on thyroid function in hypopituitary patients has hitherto been studied in small groups of children and adults with conflicting results. OBJECTIVE: We aimed to define the effect and clinical significance of adult GH replacement on thyroid status in a large cohort of GH-deficient patients. PATIENTS AND METHOD: We studied 243 patients with severe GH deficiency due to various hypothalamo-pituitary disorders. Before GH treatment, 159 patients had treated central hypothyroidism (treated group) while 84 patients were considered euthyroid (untreated group). GH dose was titrated over 3 months to achieve serum IGF-1 concentration in the upper half of the age-adjusted normal range. Serial measurements of serum T4, T3, TSH and quality of life were made at baseline and at 3 and 6 months after commencing GH replacement. RESULTS: In the untreated group, we observed a significant reduction in serum T4 concentration without a significant increase in serum T3 or TSH concentration; 30/84 patients (36%) became hypothyroid and needed initiation of T4 therapy. Similar but lesser changes were seen in the treated group, 25 of whom (16%) required an increase in T4 dose. Patients who became hypothyroid after GH replacement had lower baseline serum T4 concentration, were more likely to have multiple pituitary hormone deficiencies and showed less improvement in quality of life compared with patients who remained euthyroid. CONCLUSION: GH deficiency masks central hypothyroidism in a significant proportion of hypopituitary patients and this is exposed after GH replacement. We recommend that hypopituitary patients with GH deficiency and low normal serum T4 concentration should be considered for T4 replacement prior to commencement of GH in order to provide a robust baseline from which to judge the clinical effects of GH replacement. J Pediatr Endocrinol Metab. 2004 Oct. OBJECTIVES: Reported studies have showed alternations of thyroid hormones in critical illness mostly in adults and some in children. In this study, we aimed to measure thyroid hormone levels in children with sepsis and septic shock and investigate the relationship of these hormones with clinical state and survival. PATIENTS AND METHODS: Thyroid hormone levels of children with sepsis and septic shock, and age- and sex-matched controls were measured. RESULTS: There were 51 children in sepsis (group S), 21 children in septic shock (group SS) and 30 in the control (group C) group. Total triiodothyronine (TT3) levels were (nmol/l): 0.91 +/- 0.22, 0.64 +/- 0.23, 2.11 +/- 0.59; free triiodothyronine (FT3) (pmol/l): 0.027 +/- 0.006, 0.018 +/- 0.007, 0.049 +/- 0.010; total thyroxine (TT4) (nmol/l): 100.62 +/- 21.93, 65.79 +/- 19.35, 109.65 +/- 19.35; free thyroxine (FT4) (pmol/l): 18.06 +/- 3.87, 10.32 +/- 1.29, 19.35 +/- 3.87; and thyroid stimulating hormone (TSH) (mIU/ml): 5.0 +/- 2.0, 4.8 +/- 2.4, 5.2 +/- 3.0, in children with sepsis, septic shock, and controls, respectively. The TT3, FT3, TT4, and FT4 levels of group SS were significantly lower than those of groups S and C. The TT3 and FT3 levels of group S were lower than in group C, but there was no significant difference between TT4, and FT4 levels of groups S and C. TSH levels were slightly decreased in both sepsis and septic shock, but the difference was not significant. Eleven (21.6%) children with sepsis and 15 (71.4%) children with septic shock died (p < 0.001). The levels of TT3, FT3, TT4 and FT4 were markedly lower in non-survivors of groups S and SS compared to survivors (p < 0.001). CONCLUSIONS: These changes in the hypothalamo-pituitary-thyroidal axis may suggest a possible prognostic value of thyroid hormone levels in children with sepsis and septic shock. To the best of our knowledge, this report is the first study to compare thyroid hormone levels in a large number of patients with sepsis and septic shock with those in healthy controls in childhood. Int J Clin Pharmacol Ther. 2004 Jan. Background and objective: There are numerous, often contradictory reports on the effects of growth hormone (GH) therapy on thyroid function. The aim of this study was to assess the effect of such therapy on serum concentrations of thyroid hormones in GH-deficient children euthyroid prior to the treatment, and to determine the necessity of thyroid hormone administration in these patients. Material and methods: The study included 32 GH-deficient patients in the first stage of sexual development, in whom disorders of thyroid function could be excluded. The inclusion criteria were based on clinical examination and levels of thyroxine (T4), triiodothyronine (T3), free thyroxine (fT4), free triiodothyronine (fT3), reverse triiodothyronine (rT3), thyrotropin (TSH) before and after stimulation with thyrotropin-releasing hormone (TRH). Recombinant growth hormone (rGH) (Genotropin 16U, Pharmacia) was administered at a dose of 0.7 U/kg/week. Fasting blood samples were drawn before treatment and after 3, 6, 9 and 12 months of therapy. Thyroid hormones were measured using RIA and IRMA methods. Results: There were no physical signs of hypothyroidism in the patients examined during 12 months of rGH administration, and the satisfactory growth rate was achieved. T4 levels decreased in the first 3 months but remained within the normal range, and then returned to the values prior to the treatment. A similar trend was observed for fF4, with 28.5% of patients exhibiting fF4 levels below the normal in the 3rd month. An increase during the first 3 months of therapy was observed in the cases of T3 (statistically non-significant) and fT3, and these values then fell to levels within the normal range of patients' age. During treatment, TSH levels decreased but remained within the normal range. Conclusions: A transient decrease in T4 concentrations in the 3rd month with unchanged T3 and an increase in fT3 concentrations probably result from the effect of rGH on the peripheral metabolism of thyroid hormones. The results obtained do not support the use of thyroid hormone therapy with levothyroxine during the first year of rGH therapy in patients who are initially euthyroid. Clin Endocrinol (Oxf). 2003 Dec. Objective: Recombinant hGH treatment may alter thyroid hormone metabolism and we have recently reported that 50% of patients with GH deficiency (GHD) due to organic lesions, previously not treated with thyroxine, developed hypothyroidism during treatment with recombinant human GH (rhGH). These results prompted us to evaluate the impact of rhGH treatment on thyroid function in children with GHD. Design: Open study of GH treatment up to 12 months. Investigations were performed at baseline, and after 6 and 12 months of GH therapy. Measurement and study subjects: Serum TSH, FT4, FT3, AbTg and AbTPO, IGF-I, height and weight, were evaluated in 20 euthyroid children (group A) with idiopathic isolated GHD and in six children (group B) with multiple pituitary hormone deficiencies (MPHD) due to organic lesions. Among the latter, four already had central hypothyroidism and were on adequate LT4 replacement therapy, while two were euthyroid at the beginning of the study. Results: Serum IGF-I levels normalized in all patients. In both groups, a significant reduction in FT4 levels (P < 0.01) occurred during rhGH therapy. No patient in group A had FT4 values into the hypothyroid range, while in four of six patients in group B, fell FT4 levels into the hypothyroid range during rhGH. In particular, the two euthyroid children developed central hypothyroidism during rhGH treatment, and their height velocities did not normalize until the achievement of euthyroidism through appropriate LT4 substitution. No variation in serum FT3 and TSH levels was recorded in either groups. Conclusion: Contrary to that observed in patients with MPHD, rhGH replacement therapy does not induce central hypothyroidism in children with idiopathic isolated GHD, further supporting the view that in children with MPHD, as in adults, GHD masks the presence of central hypothyroidism. Slow growth (in spite of adequate rhGH substitution and normal IGF-I levels) is an important clinical marker of central hypothyroidism, therefore a strict monitoring of thyroid function is mandatory in treated children with MPHD. J Clin Endocrinol Metab. 2002 May. The effect on thyroid function of GH administration to 66 adult patients with severe GH deficiency was studied. Seventeen patients were euthyroid, and 49 had central hypothyroidism and were adequately treated with L-T(4). Forty patients were assigned to a low recombinant human GH (rhGH) regimen (3 microg/kg body wt.d for 3 months followed by 6 microg/kg body wt.d for another 3 months) and 26 to a higher one (6 microg/kg body wt.d for 3 months followed by 12 microg/kg body wt.d for another 3 months). Serum IGF-I, TSH, free T(4) (FT(4)), free T(3) (FT(3)), reverse T(3), T(4)-binding globulin, and antithyroid autoantibody (TgAb and TPOAb) were measured in basal condition and after 3 and 6 months of therapy. Normalization of IGF-I levels was obtained after 6-month rhGH treatment in 67% of patients, independently from the dose, whereas a significant reduction in FT(4) and reverse T(3) levels was recorded (P < 0.01), without variations in all the other parameters studied, including serum TSH, FT(3), and T(4)-binding globulin circulating levels. Antithyroid autoantibodies were detected in 11 of 66 patients (16.6%). Eight of 17 (47%) euthyroid subjects and 9 of 49 (18.3%) central hypothyroid patients, despite adequate substitution at baseline, showed FT(4) levels under the normal range at the end of the study. Altogether, 17 of 66 patients (25.7%) worsened their thyroid function. This study shows that GH deficiency masks in a consistent number of adult patients a state of central hypothyroidism. Therefore, during rhGH treatment, a careful monitoring of thyroid function is mandatory to start or adjust L-T(4) substitutive therapy. Cereb Cortex. 2000 Oct. Effects of thyroid hormone on development of the brain have been documented for over a century. Although in many respects the hypothyroid brain appears morphologically normal, functional impairments include mental retardation, ataxia and spasticity. Keyed by the discovery of nuclear receptors for thyroid hormone that function as transcription factors, recent work has examined the mechanism of thyroid hormone action in brain development. The prediction that gene expression regulated by thyroid hormone is important for mediating brain development has spurred the search for thyroid hormone-responsive genes. Here we review some of the identified genes whose expression patterns correlate with the functional deficits observed in the hypothyroid brain. Recently identified thyroid hormone-responsive genes include synaptotagmin-related gene 1 (Srg1), a putative mediator of synaptic structure and/or activity, and hairless, a transcriptional cofactor that may influence the expression of other thyroid hormone-responsive genes. Clin Endocrinol (Oxf). 2000 Aug. Objective: The effects of GH therapy on thyroid function among previous reports have shown remarkable discrepancies, probably due to differences in hormone assay methods, degree of purification of former pituitary-derived GH preparations, dosage schedules, diagnostic criteria, patient selection, duration of treatment and study design. These considerations motivated us to investigate whether and how GH replacement therapy changes serum thyroid hormone levels, including the much less studied rT3 levels, in a group of unequivocally GH-deficient children receiving long-term recombinant human GH therapy. Patients and design: Twenty clinically and biochemically euthyroid children were studied in two therapeutic conditions: on GH replacement therapy for at least 6 months and without GH replacement, either before GH was started or after GH was withdrawn for 30-60 days. Eight patients were on thyroxine replacement treatment and thyroxine doses were kept constant during the study. Blood was collected before and after 15, 20 and 60 minutes of TRH administration in both therapeutic conditions (with GH and without GH). Measurements: Concentrations of thyroid hormone levels were determined only in sera obtained before TRH administration. FT4, T3 and TSH were measured by immunoflourimetric assays and rT2 was measured by immunoradioassay. Results: Patients were classified into two groups, according to basal TSH levels: group I (TSH > 0.4 mU/l, n = 12) and group II (on thyroxine and TSH < 0.05 mU/l, n = 8). In both groups, serum FT4 levels decreased (17. 0 +/- 1.1 vs. 14.3 +/- 0.9 mU/l, P < 0.001, and 18.0 +/- 1.7 vs. 14. 2 +/- 1.7 mU/l, P < 0.01, respectively), serum T3 levels increased (1.8 +/- 0.1 vs. 2.4 +/- 0.2 nmol/l, P < 0.001, and 1.9 +/- 0.3 vs. 2.4 +/- 0.2 nmol/l, P < 0.05, respectively), and serum rT3 levels decreased (0.35 +/- 0.03 vs. 0.25 +/- 0.03 nmol/l, P < 0.01, and 0. 48 +/- 0.06 vs. 0.34 +/- 0.06 nmol/l, P < 0.01, respectively). Basal (3.2 +/- 0.50 vs. 2.6 +/- 0.72 mU/l, P = 0.28, paired t-test), TRH-stimulated peak TSH levels (13.9 +/- 5.3 vs. 15.9 +/- 8.0 mU/l, P = 0.35, paired t-test) and TRH-stimulated TSH secretion, expressed as area under the curve (609 +/- 97 vs. 499 +/- 53 mU/l.minutes-1, P = 0.15, paired t-test), remained unchanged during GH replacement in group I patients. Low serum FT4 and high serum T3 levels were observed in only one patient each, but low serum rT3 levels were found in six patients (four in group I and two in group II) during GH replacement. Conclusions: These results show that long-term GH replacement therapy in children with unequivocal GHD significantly decreases serum FT4 and rT3 levels and increases serum T3 levels; that these changes are independent of TSH and result from increased peripheral conversion of T4 to T3 and that GH replacement therapy in GH deficient children does not induce hypothyroidism, but simply reveals previously unrecognized cases whose serum FT4 values fall in the low range during GH replacement. Horm Res. 1999. Growth hormone regulates several other hormonal systems and vice versa. The present review focusses on the effect of GH administration in adults on selected hormonal systems. Growth hormone treatment has been linked to development of central hypothyroidism in hypopituitary children. We now know that GH enhances the extra-thyroidal conversion of T(4) to T(3). Lowering of T(4) during GH treatment therefore reflects biochemical unmasking of subclinical central hypothyroidism. In normal adults GH administration does not affect the pituitary-gonadal axis. There is, however, evidence to suggest that GH substitution in hypopituitary adults enhances peripheral actions of sex steroids (males) and stimulates gonadal function (females). Both increased, unchanged and reduced basal and ACTH stimulated glucocorticoid levels have been reported during GH treatment. Several groups have recorded reduced levels of cortisol binding globulin with unchanged free cortisol concentrations. Regular assessment of thyroid and glucocorticoid status during GH substitution in GH-deficient patients is recommended. J Clin Endocrinol Metab. 1998 Oct. The occurrence of central hypothyroidism in previously euthyroid children during GH therapy has been reported with widely varying incidence. We monitored the acute effects on the hypothalamic-pituitary-thyroid axis in 15 euthyroid children with classic GH deficiency during the first year of GH therapy. All were initially euthyroid, as assessed by normal baseline TSH, T4, free T4, and T3 levels and negative antithyroid antibodies. A thyroid profile (T4, free T4 index, T3, rT3, and TSH) was performed at baseline and 1, 3, 6, 9, and 12-15 months after GH therapy began; a TRH stimulation test was performed at baseline and after 1, 3, and 9 months of therapy. By 1 month, there were significant decreases in T4, free T4 index, and rT3, and significant increases in T3 and the T3/T4 ratio. The changes from baseline values were greatest at 1 month, were almost universal for all thyroid values, and showed a gradual return to baseline from 3-12 months. There were no clinical signs of hypothyroidism and no change in baseline or TRH-stimulated TSH levels or in cholesterol levels, and all patients grew at velocities expected for the treatment schedule. There is little evidence for the development of clinically significant hypothyroidism in the great majority of initially euthyroid patients after GH therapy is begun. T4 supplementation is seldom needed in such patients. Zhonghua Nei Ke Za Zhi. 1997 Nov. To evaluate the effect of growth hormone treatment on thyroid function of growth hormone deficient children, 19 (18M/1F) euthyroid children of growth hormone deficiency (GHD) were treated with Genotropin, a recombinant human growth hormone (rhGH) for 12 months. rhGH was injected subcutaneously with a daily dosage of 0.1 IU/kg. All the patients were diagnosed by two GH provocative stimulating tests with the serum GH peak level < 7 micrograms/L. During the treatment, blood was drawn before or 6 and 12 months after the initiation of therapy to measure serum T3, T4, FT3, FT4, rT3 and thyroid-stimulating hormone (TSH) levels. In the meantime, thyrotropin releasing hormone (TRH) stimulating test was performed by an i.v. injection of 200 micrograms synthetic TRH. The results showed that (1) the average serum levels of T4 and FT4 decreased significantly 6 at the 6th and 12th month (P < 0.001), while the serum FT3 level decreased only at the 6th month (P < 0.05). The serum T3, rT3 and TSH concentrations remained unchanged. (2) 8 euthyroid patients (45%) became subclinical hypothyroidism after 12 months' treatment with rhGH for their serum FT4 levels fell to below the normal range. The 19 patients were divided into thyroid function normal (n = 11) and subnormal group (n = 8) according to their posttreatment thyroid functions. (3) The TSH response to TRH was evaluated by the area under the curve (AUC) of serum TSH. The average AUC was greater in the subnormal group than in the normal group whether before or 6 and 12 months after the treatment. The greater TSH response to TRH among patients with decreased posttreatmental FT4 levels suggests that latent TRH deficiency has already existed, which may be the pathogenetic basis of the hypothyroidism developped after rhGH treatment. Thus the thyroid function of GHD patients should be monitored during rhGH treatment in order that the thyroxine replacement therapy can be given in time. J Endocrinol Invest. 1996 Sep. Pituitary-thyroid changes have been reported during recombinant human growth hormone (rhGH) therapy at the dose commonly used in prepuberty. We have previously demonstrated that low doses of rhGH were able to normalize body composition and both cardiac structure and function in growth hormone deficient adults (GHDA), without causing any of the side effects described when the GHDA were treated with doses commonly employed in the GHD children. The aim of this study was to evaluate the behaviour of pituitary-thyroid parameters in GHDA undergoing such a low dose of rhGH treatment. We studied 9 (2 females and 7 males, 25-34 yr) GHDA, 7 congenital and 2 acquired GH deficiency, before, during and after a 12-month rhGH treatment of dose of 10 micrograms/kg/day (= 70 micrograms/kg/week) divided in 3 injections, administered sc at 20:00 h on Monday, Wednesday and Friday, respectively. Thyroid deficiency and other hormonal deficiencies, when present, had been adequately corrected with replacement therapy. Serum IGF1, T3, T4, free-T3, free-T4, TSH, reverse-T3, T3/T4 and FT3/FT4 ratios were studied basally, every 3 months during the 12-month rhGH treatment and every 3 months for a period of 12 months off therapy. Analysis of variance (ANOVA) was performed as statistical method. All parameters (except IGF1) did not show any variation during and after rhGH treatment at low doses. The alterations of T3 and T4 metabolism, in the sense of a T3 increase and a T4 reduction, caused sometimes by rhGH treatment, could be due to the higher doses used and therefore should be considered another side effect, like artrhalgia, fluid retention, carpal tunnel syndrome, etc. Metabolism. 1996 Aug. The role of growth hormone (GH) and thyroid hormone in the regulation of lipid and lipoprotein metabolism is not fully established. Furthermore, the possible linkage between the well-known GH-induced increase in peripheral thyroxine (T4) to triiodothyronine (T3) generation and the effects of GH on lipid and lipoprotein metabolism has not been elucidated. In this double-blind placebo-controlled study, we compared the effects of GH and T3 administration alone and in combination on lipid and lipoprotein metabolism in a group of healthy young adults. The dose of T3 was selected to mimic the T2 increase seen during exogenous GH exposure. Eight normal male subjects (aged 21 to 27 years; body mass index, 21.11 to 27.17 kg/m2) were randomly studied during four 10-day treatment periods with (1) daily subcutaneous placebo injections and placebo injections and placebo tablets, (2) daily subcutaneous GH injections (0.1 IU/kg.d) and placebo tablets, (3) daily T3 administration (40 micrograms on even dates or 20 micrograms on uneven dates) plus placebo injections, and (4) daily GH injections plus T3 administration. GH administration increased free T3 (FT3) to the same level as during T3 administration. GH caused decreased levels of total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol and increased levels of triglycerides (TG) and lipoprotein(a) (Lp(a)), but no changes in high-density lipoprotein (HDL) cholesterol and apolipoprotein B (apo B). T3 administration caused no alteration in these parameters, except for decreased levels of TC comparable to those seen after GH administration. Combined GH and T3 administration caused changes identical to those seen after GH administration, in addition to decreased apo B levels and a further decrease of TC levels. We conclude that GH and iodothyronines in the physiologic range exert distinct but disparate effects on lipids and lipoproteins, and do not support the hypothesis that the effects observed during GH administration are exclusively secondary to changes in peripheral T3 levels. Eur J Endocrinol. 1996 May. Insulin-like growth factor I (IGF-I) is considered to mediate some of the growth-promoting and metabolic effects of growth hormone (GH). Growth hormone treatment of healthy and GH-deficient subjects is accompanied by increased conversion of thyroxine (T4) to triiodothyronine (T3) in peripheral tissues. Whether these effects are mediated by IGF-I is unknown. To assess the respective roles of these hormones on thyroid hormone metabolism we have treated two groups of subjects. The first group consisted of eight healthy subjects who were treated with IGF-I (10 micrograms.kg-1.h-1 sc for 5 days). The second group consisted of eight subjects with combined GH and thyrotropin (TSH) deficiency due to acquired pituitary disease. They were treated with IGF-I (10 micrograms.kg-1.h-1 sc for 7 days), GH (2 IU m-2 sc q.i.d.) or both hormones together. The IGF-I treatment in healthy subjects led to an increase in free T3 (FT3) and a reduction in TSH levels, whereas FT4 and total T4 (TT4) levels remained unchanged. In the second group-in which all subjects were substituted with oral L-thyroxine-treatment with IGF-I led to an elevation of FT3 in the face of unchanged T4 levels. Growth hormone alone and GH plus IGF-I resulted in a more pronounced elevation in T3 level. The results suggest that IGF-I partially mediates the well-known effects of GH on peripheral conversion of T4 to T3. However, GH has more pronounced effects on thyroid hormones that apparently are not mediated by IGF-I. J Clin Endocrinol Metab. 1995 Dec. Carbohydrate-deficient glycoprotein (CDG) syndrome is a newly recognized hereditary disorder that presents with psychomotor retardation, cerebellar ataxia, peripheral sensorimotor neuropathy, and, variably, skeletal abnormalities, lipodystrophy, and retinitis pigmentosa. These abnormalities appear to be produced by a defect that causes reduced carbohydrate content in glycoproteins. We studied seven patients with CDG type I belonging to five unrelated families. The concentration of serum TBG, a glycoprotein of hepatic origin, was measured by RIA and T4 saturation and was found to be below the normal range in three of the seven patients and normal in four of them. More than half of the total serum TBG had reduced sialic acid content and localized on isoelectric focusing (IEF) as two prominent bands cathodal to the three major bands of normal TBG. The latter two bands are responsible for the characteristic IEF pattern or CDG syndrome. TBG in patients with CDG had immunoreactivity indistinguishable from that of normal TBG and had normal affinity for T4, T3, and rT3. Serum total T4, T3, and rT3 were below the normal range in seven, five, and seven patients, respectively. The free T4 index was also below normal in four patients, but the free T4 concentration, measured by equilibrium dialysis at low dilution, and serum TSH were in the midnormal range. The serum total T4 and rT3 levels were disproportionately reduced relative to the serum TBG concentration and compared to the concentrations of these iodothyronines in matched subjects with inherited partial TBG deficiency. Chronic illness cannot explain these changes, because, contrary to patients with nonthyroidal illness, those with CDG had significantly higher serum total T3/T4 and lower rT3/T4 ratios. It is concluded that IEF of TBG is a rapid and simple method for the diagnosis of CDG type I and that the abnormal pattern can be detected as early as 5 days postpartum. Patients with CDG are chemically euthyroid, and it is postulated that the reduction in serum iodothyronine concentrations beyond that explained on the basis of low TBG levels may be due to the interference with binding to TBG by an unidentified substance. Thyroidology. 1994 Dec. Thyroid hormones and the GH/IGF-1 system show considerable mutual interference which may have physiological, pathophysiological and clinical importance. GH therapy of children and adults may induce a fall in serum T4, which seems to be due to an effect on the deiodination of T4 to T3. Animal studies suggest that the alterations in thyroid hormones in tissue may be much more prominent than the changes observed in serum. It is possible that the GH deficiency seen in the majority of patients with pituitary/hypothalamic disorders may mask secondary hypothyroidism in some patients by giving a relatively high serum T4. GH therapy may then unmask the hypothyroidism. In accordance with such a mechanism GH deficient children evaluated thoroughly to exclude secondary thyroid failure before GH administration do not develop thyroid insufficiency during GH substitution therapy. It is suggested that thyroid insufficiency should be considered in GH deficient patients with low normal serum T4. Arzneimittelforschung. 1991 Dec. The influence of alpha-lipoic acid (LA, thioctic acid, CAS 62-46-4) on thyroid hormone metabolism and serum lipid-, protein- and glucose levels was investigated. In the first setup of experiments administration of LA together with thyroxine (T4) for 9 days suppressed the T4 induced increase of T3 generation by 56%. This suppression was similar to that affected by 6-propylthiouracil (54%). LA or T4 alone did not affect the cholesterol level, but together they led to a reduction. LA decreased the triglyceride level by 45%; the decrease induced by T4 or LA plus T4 was not significant. Total protein and albumin levels decreased by LA plus T4 treatment when compared to the LA control. The slight increase in glucose level by LA or T4 alone was not observed when they were administered together. In the second setup of experiments the administration of T4 for 22 days increased the serum T3 level 3-fold. When LA was combined with T4 and the treatment continued, the T3 production decreased by 22%. T4 reduced cholesterol level by 30%, and LA plus T4 further reduced it by 47%. The triglycerides were not affected. A moderate decrease in total protein was observed after treatment with T4 plus LA; T4 and LA plus T4 decreased the albumin level. The decrease in serum glucose by T4 recovers by LA treatment. These results demonstrate that LA interferes with the production of T3 from T4 when it is co-administered with T4. The elevated level of T3, after T4 administration, is reduced by treatment with LA. |