[Hypertension: once primary, always primary?].

Three patients diagnosed with primary hypertension suddenly developed hard-to-treat blood pressure after several years of stable blood pressure. One patient, a man aged 48 years, had developed a renal artery stenosis, which had not been present five years earlier. The other two patients, a man aged 57 years and a woman aged 27 years, were diagnosed with an aldosterone-producing adenoma of the left adrenal gland and a pheochromocytoma, respectively. In patients with previously stable blood pressure, sudden derangement may be due to secondary hypertension on top of the pre-existing primary hypertension. A thorough history and physical examination together with limited laboratory investigations usually leads the way to the correct diagnosis.