Long-Term Follow up of Thyroid Functions in Patients with Successful Renal Transplantation (RT)

Ryu, Mee Sook; Hong, Seong Pyo; Lee, Tae Won; Ihm, Chun Gyoo; Kim, Myung Jae

Abstract

BACKGROUND: Thyroid status in uremia is still inconclusive due to the complexicity of the system. No single pathogenetic event may explain the thyroid function abnormalities in end stage renal disease (ESRD). Defects at all levels of the hypothalamic-pituitary-thyroid axis have been identified. Regarding the thyroid dysfunction in ESRD it is well recognized that the TSH response to TRH is blunted and serum concentrations of thyroid hormones are decreased in patients with ESRD. Whether or not on maintenance hemodialysis. Restoration of renal function with renal transplantation resulted in normalization of all parameters of thyroid function with exception of blunted TSH response to TRH. We evaluated the long-term changes of the thyroid function in 10 patients to know whether the thyroid function and the hypothalamo-pituitary axis were improved with the recovery of the renal function under maintenance low-dosage steroid administration after renal transplantation.
METHODS
These tests were performed during the morning in the fasting state in 10 ESRD patients before, 1 month and 6 years after renal transplantation (RT). Thyroid function tests. Serum T3, T4 were measured by RIA kit and serum TSH was measured by IRMA kit. TRH stimulation test. Serum blood samples were obtained 0, 30, 60, 90, 120 min after TRH (400microgram) administration. Statistical analysis. All grouped data were expressed as mean+/-SD. Student t-test was used to assess the statistical difference between any two means.
RESULTS
1) The mean basal level of serum T3 was reduced in ESRD patients (53.6+/-33.2ng/dL) and increased to the low normal level 1 month after RT (87.8+/-25.4ng/dL), improved to the normal level 6 years after RT (116.3+/-28.8ng/dL). 2) The mean basal level of T4 was within normal range before RT (5.9+/-1.1microgram/dL), after 1 month (6.2+/-1.2microgram/dL) and after 6 years (6.5+/-1.4microgram/dL) of RT. 3) The mean basal level of TSH was within normal range before RT (2.0+/-1.2microU/mL), after 1 month (1.1+/-0.7microU/mL), and after 6 years (0.7+/-0.5microU/mL) of RT. Rut the mean TSH level of 6 years of RT was significantly decreased within the normal range. 4) In ESRD the TSH response to TRH was blunted, had a diminished peak and delayed fall before RT. After 1 month of RT, the TSH response to TRH was persistently blunted, however showed more rapid fall of TSH. After 6 years of RT, the TSH response to TRH normalized, but the absolute level of TSH and the peak level of TSH to TRH were less than before and after 1 month of RT.
CONCLUSIONS
The abnormalities of thyroid hormones in uremic patients were improved partially after 1 month of RT and almost completely after 6 years of RT. But the level of T3H and the peak level of TSH to TRH were low within normal range, these results may be a direct consequence of low-dosage and long-term glucorcorticoid administration.