Correlation between Renal Function Tests and Thyroid Hormones in Sudanese Patients with Hypo- and Hyperthyroidism

Background Thyroid hormones affects functions of organ systems including the renal system, in which creatinine, blood urea nitrogen (BUN) and glomerular filtration rate (GFR) are affected. This study aimed to evaluate levels of creatinine, BUN and GFR in patients with hypo and hyperthyroidism and to correlate them with thyroid stimulating hormone (TSH), thyroxin (T4) and triiodothyronine (T3) levels. Methodology A cross sectional descriptive study was conducted involving a total of 117 subjects in three groups 37 hypothyroidism, 40 hyperthyroidism and 40 apparently healthy subjects as control. Plasma TSH, T4, T3, creatinine, blood urea nitrogen (BUN) and albumin were determined, glomerular filtration rate (GFR) was calculated according to MDRD equation. Results Mean creatinine in hypothyroidism was 0.90.1 mg/dl, in hyperthyroidism was 0.70.2 mg/dl, while in control was 0.60.1 mg/dl, mean BUN in hypothyroidism was 112.9 mg/dl, and in hyperthyroidism was 142.5 mg/dl while in control was 103.2 mg/dl, mean estimated GFR in hypothyroidism was 10017 ml/min, and in hyperthyroidism was 14332 ml/min while in control was 16323 ml/min. Correlation studies reveled that creatinine in hypothyroidism was significantly positive correlated with TSH and significantly negative correlated with T4 and T3, while in hyperthyroidism was significantly positive correlated with T4 and not correlated with TSH, BUN in hypothyroidism was significantly positive correlated with TSH but not correlated to T4 and T3 while in hyperthyroidism there is no correlation between BUN and thyroid hormones. GFR in hypothyroidism was significantly negative correlated with TSH and significantly positive correlated with T4 and T3 while in hyperthyroidism no correlation between GFR and thyroid hormones. Conclusion Both overt hypo and hyperthyroidism significantly increase creatinine and BUN level while significantly decrease eGFR. Thyroid dysfunction significantly affects renal functions so normal functioning thyroid is needed for healthy kidney performance.