ABSTRACT
In thyrotoxicosis, changes in urine output and serum creatinine [Cr] concentration has been related to increased glomerular filtration rate [GFR]. The aim of this study is to clarify the mechanism of these changes. Forty-one thyrotoxic patients, 9 male and 32 female with the age range of 16-62 years were selected and body weight, 24-h urine output, serum and urine Cr concentration, and GFR were measured in the thyrotoxic state and two months after treatment. The data was analyzed by student 't' test and paired 't' test. The following parameters were measured and are compared in thyrotoxic and euthyroid states respectively. Body weight: 58.4 +/- 10.6 Kg and 61.6 +/- 10.4 Kg after receiving anti-thyroid therapy [p<0.001]. 24-h urine output: 1430 +/- 420 ml, and 1165 +/- 450 ml [p <0.001]. Serum creatinine concentration: 0.7 +/- 0.11 mg/dl, and 0.84 +/- 0.13 mg/dl [p<0.001]. 24-h urine creatinine concentration: 906 +/- 225 mg/l and 1081 +/- 285 mg/l [p<0.001]. The change in GFR was not statistically significant, being 90.1 ml/min before therapy and 89.5 ml/min in the euthyroid state. Increased urine output and decreased serum creatinine concentration in thyrotoxicosis is not GFR related