Ectopic production of renin by ileal carcinoma.

A 54-yr-old woman with the symptoms of primary reninism, i.e. hypertension, metabolic alkalosis and elevated levels of plasma renin activity (PRA) and aldosterone, is described. She had an ileal cancer secreting active and inactive renin. The symptoms markedly improved after resection of the tumor. In the tumor active and inactive renin were proved to be present by an assay of angiotensin I formation in the presence and absence of renin antibody, and renin immunoreactivity was found immunohistochemically. The mRNA coding for the renin precursor was identified in the RNA-rich extract of the tumor by blot hybridization analysis with the human renin cDNA as a probe. The mRNA from the tumor was shown to be identical in molecular size to that from the human kidney by agarose gel electrophoresis. This is the first description of an ectopic renin-producing ileal carcinoma and the first demonstration of renin mRNA in the tumor tissue.