DIURNAL VARIATION OF 17-HYDROXYCORTICOSTEROIDS, SODIUM, POTASSIUM, MAGNESIUM AND CREATININE IN NORMAL SUBJECTS AND IN CASES OF TREATED ADRENAL INSUFFICIENCY AND CUSHING'S SYNDROME*†

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Abstract
The morning rise and the nocturnal drop in plasma and urinary levels of 17-hydroxycortieosteroids (17-OH-CS) and in urinary sodium, potassium and endogenous creatinine clearance are described in 8 normal subjects receiving a controlled diet composed of equal feedings every three hours. Magnesium excretion was highest during the period of lowest sodium and potassium excretion (3 A.M. to 6 A.M.). Endogenous creatinine clearance had two peaks (6 P.M. to 9 P.M. and 6 A.M. to 9 A.M.) with two low periods (noon to 3 P.M. and 2 A.M. to 6 A.M.). A definite increase in both sodium and potassium excretion was noted during oral administration of graded dosages of cortisol hemisuccinate in patients with treated adrenal insufficiency. Rapid intravenous injection of 5 mg. of cortisol hemisuccinate every three hours into similar subjects obliterated the variations in creatinine clearance but failed to influence decisively the nocturnal drop in sodium, potassium and magnesium excretion. Magnesium excretion was not influenced by administration of cortisol in either group. Five subjects with Cushing's syndrome due to bilateral adrenal hyperplasia had constant levels of 17-OH-CS in plasma and urine throughout the twenty-four hours. These 17-OH-CS values were most strikingly abnormal when compared to normal nocturnal values. The disturbed rhythm in 17-OH-CS levels in these patients was associated with a disturbance in sodium and potassium excretion, but the noctural excretion peak for magnesium was normal.