[Secondary hypertension: diagnosis and treatment]

Hypertension does not recognize obvious pathogenic causes in the majority of patients (essential hypertension). However, a secondary underlying cause of hypertension can be recognized in 5-10% of unselected hypertensive patients, and this prevalence may increase to more than 20% in patients with hypertension that is difficult to control or frankly resistant to treatment. In children, secondary hypertension is most often due to aortic coarctation, distal thoracic or abdominal aortic stenosis, or specific gene mutations. In adults or elderly individuals, secondary hypertension is most often due to atherosclerotic renal artery stenosis, primary hyperaldosteronism, and Cushing's disease or syndrome. Parenchymal nephropathy and hyperparathyroidism can cause hypertension at all ages, while pheochromocytoma and paraganglioma tend to occur more often in adolescents or young adults. In general, secondary hypertension should be suspected in subjects with: (a) onset of hypertension under 30 years of age especially if in the absence of hypertensive family history or other risk factors for hypertension; (b) treatment-resistant hypertension; c) severe hypertension (>180/110 mmHg), malignancy, or hypertensive emergencies; d) rapid rise in blood pressure values in previously well controlled patients. Any clinical signs suspicious or suggestive of hypertension from endocrine causes, a "reverse dipping" or "non-dipping'" profile at 24 h ambulatory blood pressure monitoring not justified by other factors, signs of obvious organ damage may be helpful clues for diagnosis. Finally, patients snoring or with clear sleep apnea should also be considered for possible secondary hypertension.