The frequency of secondary hypertension.

In a series comprising 482 patients with hypertension requiring treatment 79 percent had to be classified as essential hypertension. Bilateral renal disease was found in 9 percent, unilateral renal disease in 3.3 percent, but only one patient underwent surgery. Renal artery stenosis was found in 24 patients (5 percent), but only 5 (1 percent) were operated on. Two cases of primary hyperaldosteronism and one of phaeochromocytoma were found; in all three surgical intervention was successful. Oral contraceptives had caused the elevated BP in 7 patients (1.5 percent). It is emphasized that the frequency of curable hypertension is still very low and this should be taken into account when routine examination of patients with hypertension requiring treatment is discussed.