The effect of 1α-hydroxyvitamin D3 on renal function in normal subjects

Abstract The effects of short-term administration of 1 μg daily of 1α-hydroxyvitamin D 3 (1αOHD 3 ) on plasma biochemistry and renal function have been studied in six normal subjects using the 51 Cr-labelled edetic acid ( 51 Cr-EDTA) infusion method to measure glomerular filtration rate. 1αOHD 3 was administered for two weeks, subjects being studied before treatment, at the end of the first and second weeks of treatment and one week after stopping treatment. Mean plasma creatinine concentration rose throughout the four weeks of the study, but this change was not statistically significant. Plasma creatinine levels in fact decreased in two subjects after 1αOHD 3 administration. There was no significant change in glomerular filtration rate as measured by the 51 Cr-EDTA infusion method or in endogenous creatinine clearance. Plasma phosphate levels increased in all subjects during 1α0HD 3 administration and the maximum tubular reabsorption capacity for phosphate relative to the glomerular filtration rate (Tm po4 /GFR) increased in five. There were no significant changes in plasma calcium or immunoreactive parathyroid hormone levels. It is concluded that short-term administration of 1αOHD 3 , 1 μg daily, has no direct adverse effect on glomerular filtration rate in subjects with normal renal function.