TSH Response to TRH in Hemodialysis and CAPD Patients

Abstract

The thyroid status was studied in 19 uremic patients (11 on HD and 8 on CAPD) and in a group of 17 healthy adult patients. In uremic patients T₃ and T₄ were significantly reduced (p < 0.001) and rT₃ was increased (p < 0.001). The time course TSH response to TRH showed a lower peak response (in 5 patients it did not exceed 5 μU/ml) which on turn was also delayed (the peak was observed at 60 minutes in 63% of them). TSH concentrations in uremics were increased at 0 time (p < 0.02), lower at 20 minutes (p < 0.01) and increased at 120 minutes (p < 0.02). No difference existed between HD and CAPD. The thyroid response to TSH was normal as showed by a normal percent increase over basal values of T₃ concentrations at 120 minutes. Uremic patients also showed a peak GH response at 20 minutes which was not observed in controls. The data exclude the existence on a primary form of hypothyroidism and point to the existence of hypothalamic-pituitary abnormalities, which should not be taken as indicative of secondary and/or tertiary hypothyroidism since FT₄ values were normal in HD and increased in patients undergoing CAPD (p < 0.05) who on turn showed lower plasma albumin concentrations (p < 0.05).