Nonaldosterone mineralocorticoids, such as deoxycorticosterone (DOC) and 18-hydroxy-DOC, have been reported to be elevated in some patients with primary aldosteronism (PA). Since DOC is a probable precursor of a more potent mineralocorticoid, 19-nor-deoxycorticosterone (19-nor-DOC), this study evaluated urinary free (UF) 19-nor-DOC excretion in 6 patients with PA and compared the results to those from 11 patients with low renin hypertension (LRH) and 7 normotensive subjects. PA was due to either an aldosterone-producing adenoma (APA; 4 patients) or bilateral adrenal hyperplasia (2 patients) diagnosed by adrenal venous catheterization or surgery. Compared to LRH subjects, patients with PA had a higher mean blood pressure (137 +/- 9 vs. 114 +/- 3 mm Hg), a lower plasma potassium level (3.1 +/- 0.2 vs. 3.9 +/- 0.1 meq/1) and greater renin suppression (0.3 +/- 0.1 vs. 0.6 +/- 0.1 ng angiotensin I/ml . h). UF 19-nor-DOC levels were elevated in PA subjects compared to those in normotensives (3,716 +/- 1,517 vs. 428 +/- 112 ng/day) but not compared to those in LRH patients (1,237 +/- 471). Two patients with APA had distinctly elevated UF 19-nor-DOC levels (11,137 and 7,744 ng/day), but another APA patient had the lowest value (305 ng/day). UF 19-nor-DOC positively correlated with the aldosterone secretion rate in PA (r = 0.75) but not LRH subjects. In conclusion, this study demonstrates that patients with PA may have elevated levels of UF 19-nor-DOC which are proportional to the aldosterone excess and could be a contributing factor to the hypertension, hypokalamia, and excess mineralocorticoid activity of this disease.