Function of the hypothalamo-hypophysial-thyroid axis in chronic renal failure

Area of Science:

• Endocrinology
• Nephrology
• Internal Medicine

Background:

• Chronic renal failure (CRF) can affect various endocrine functions.
• Thyroid hormone metabolism and hypothalamic-pituitary-thyroid axis regulation are complex and may be altered in CRF.

Purpose of the Study:

• To investigate the hypothalamic-pituitary-thyroid function in patients with chronic renal failure.
• To assess thyroid hormone levels, binding proteins, peripheral conversion, and hormonal responses to thyrotropin-releasing hormone (TRH) in CRF patients.

Main Methods:

• Studied 25 patients with chronic renal failure (8 conservative, 9 peritoneal dialysis, 8 hemodialysis).
• Measured total and free thyroxine (T4) and triiodothyronine (T3) levels.
• Assessed thyrotropin (TSH) response to TRH and growth hormone (GH) release.

Main Results:

• All patients were clinically euthyroid.
• Reduced total T4 and T3 levels observed.
• Normal free T4, but reduced free T3 in severe renal failure; reduced TSH response to TRH; GH release by TRH in some patients, possibly due to malnutrition.

Conclusions:

• Reduced binding of thyroid hormones to transport proteins and impaired peripheral T4 to T3 conversion are suggested in renal failure.
• The reduced TSH response to TRH appears independent of thyroid hormone metabolism changes.
• Growth hormone release by TRH may indicate protein malnutrition in CRF patients.