Dynamic changes in biochemical markers of renal function with thyroid status- A study in Indian population

Abstract

Thyroid dysfunction is known to cause significant changes in glomerular filtration rate. The present cross-sectional study was performed to evaluate the changes in biochemical markers of renal function in hypothyroid subjects before and after treatment. Thyroid function tests (T 3 , T 4 and TSH levels) were assayed in 385 subjects. Based on TSH levels, subjects were classified as euthyroid (n=198), sub-clinical hypothyroid (n=98; TSH 6.1 to 19.9 μIU/ml) and overt hypothyroid (n=89; TSH ≥ 20 μIU/ml, abnormally low T 4 levels). Forty-eight hypothyroid patients were re-evaluated after 3 months of thyroxine replacement therapy. Renal function tests were carried out in all subjects and statistically analyzed. Serum creatinine was significantly increased in sub-clinical and overt hypothyroid groups as compared to euthyroid subjects. Serum creatinine showed a significant negative correlation with T 3 &T 4 levels in overt group(r = -0.372 and r = -0.371), whereas a positive correlation was observed with TSH (r=0.283). Uric acid levels were significantly increased in the overt group as compared to euthyroid subjects. Uric acid levels showed a significant negative correlation with T 3 levels in the overt group (r= -0.298). After 3 months of thyroxine replacement therapy, creatinine and uric acids levels decreased significantly and were comparable to euthyroid levels. Hypothyroidism leads to reversible changes in renal function.