Urinary free corticosteroid excretion and renal function.

Abstract

Theoretically urinary free corticosteroid excretion should be affected by renal function and this would make it a less sensitive index of hypercortisolemia. In 28 consecutive urine human samples there was a clear relationship (r [correlation coefficient] = 0.83; P < 0.001) over a range of creatinine clearances 0.3-200 ml/min. Although an allowance was made for renal function this would not necessarily improve the discrimination of normal from abnormal. Until data comparing corrected to uncorrected urinary free corticosteroid excretion become available a short dexamethasone test is recommended as the initial investigation in patients with suspected hypercortisolemia and abnormal plasma creatinine concentrations.