The circadian periodicity of urinary 17-ketosteroids, corticosteroids, and electrolytes in congenital adrenal hyperplasia.

The circadian periodicity of adrenal function in patients with congenital virilizing adrenal hyperplasia (CAH) was examined by measuring the urinary 17-ketosteroids, 17-hydroxycorticosteroids, sodium, and potassium. Patients with the salt-losing and the non-salt-losing types were studied with and without treatment. Cosine curves were fitted to the data by the least-squares method to determine the mesors, amplitudes, and acrophases of the variable for each patient. The data reveal distinct circadian rhythms for all variables measured whether or not the patient was receiving treatment. The acrophases for 17-ketosteroids and 17-hydroxycorticosteroids were between 1500 and 1800 h. These acrophases are about 6 h later than those for normal subjects. The treatment on a fixed daytime schedule for many years may have shifted the natural rhythm.