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Evidence of hypothalamic-pituitary thyroid abnormalities in children with end-stage renal disease
T Pasqualini1, D Zantleifer, M Balzaretti
1Departamento de Pediatria, Hospital Italiano de Buenos Aires, Argentina.
Insights
Children with end-stage renal disease often have abnormal thyroid function. This study in pediatric patients suggests central hypothyroidism may be a contributing factor to altered thyroid hormone levels in these patients.
Area of Science:
- Pediatric Endocrinology
- Nephrology
- Thyroidology
Background:
- End-stage renal disease (ESRD) in children can be associated with growth and hormonal abnormalities.
- Altered thyroid function is a recognized complication in ESRD patients, but underlying mechanisms require further elucidation.
Purpose of the Study:
- To investigate the mechanisms behind altered thyroid function in children with ESRD.
- To evaluate thyroid hormone levels, thyrotropin (TSH) response, and circadian TSH patterns in pediatric ESRD patients.
Main Methods:
- Serum thyroid hormone levels (total T4, free T4, total T3) were measured before and after hemodialysis.
- Thyroid-stimulating hormone (TSH) response to thyrotropin-releasing hormone (TRH) was assessed.
- Circadian patterns of serum TSH, including the nocturnal surge, were analyzed in nine pediatric ESRD patients.
Main Results:
- All patients exhibited low serum free T4 levels; four had low total T4.
- Thyroid hormone levels normalized immediately post-hemodialysis, independent of fluid or hematocrit changes.
- Three patients showed a deficient and prolonged TSH response to TRH, and five had a blunted nocturnal TSH surge.
Conclusions:
- Pediatric ESRD patients frequently present with low free T4 and impaired TSH secretion patterns.
- Findings support the hypothesis of central hypothyroidism in some children with end-stage renal disease.
- Altered thyroid hormone regulation in ESRD may involve central (hypothalamic-pituitary) mechanisms.
Abstract:
Patients with end-stage renal disease may have abnormalities of growth and of gonadal and thyroid hormones, so we attempted to determine the mechanisms that may be involved in the altered thyroid function. We evaluated serum thyroid hormone levels, their changes immediately after hemodialysis, the serum thyrotropin (thyroid-stimulating hormone (TSH) response to thyrotropin releasing hormone, and the circadian pattern of serum TSH in nine children with end-stage renal disease who were between 7 1/2 years and 17 years 1 month of age. Seven patients had been receiving hemodialysis for a median of 3.3 years; the other two were receiving continuous ambulatory peritoneal dialysis. Four patients had low serum total thyroxine (T4) values, and all nine had low free T4 values. Mean concentrations of total T4, free T4, and total triiodothyronine (T3), which were significantly less than normal before hemodialysis, returned to normal levels immediately after dialysis. Postdialysis thyroid hormone increases did not correlate with the decrease in weight or the increase in hematocrit observed immediately after dialysis. All but one patient had basal TSH levels within the normal range. Three patients had a deficient TSH response to thyrotropin releasing hormone, and the TSH response was prolonged in all of them. The mean (+/- SD) nocturnal TSH surge was 50 +/- 68%. Five of the eight patients studied had a nocturnal TSH surge below the normal range (95% confidence limits 47% to 300%). Serum free T4 values correlated with the TSH nocturnal surge (r, 0.73; p less than 0.05). Our findings support the hypothesis that some patients with end-stage renal disease have central hypothyroidism.