Renin and inactive renin (prorenin) in the plasma of patients with malignant renal tumours.

Plasma active and inactive renin (porenin) concentrations were measured in 26 adults with renal carcinoma and 8 children with nephroblastoma. In patients with carcinoma, plasma total renin concentration was slightly raised in 8 patients and markedly in one, in whom the increase was due to a more than 10-fold excess of inactive renin. Total renin concentration was raised in 7 out of 8 cases of nephroblastoma, the increase being due to excess inactive renin. It is likely that this represented oversecretion of a renin precursor, as inactive renin from the plasma of a patient with renal carcinoma showed similar biochemical characteristics to pure human prorenin.