Prospective evaluation and characteristics of patients with suspected primary hyperaldosteronism

Primary hyperaldosteronism (PH), resulting in hypokalaemic hypertension, may be due to an aldosterone-producing adenoma (APA) or bilateral zona glomerulosa hyperplasia. Six patients with suspected PH were identified at the University Hospital of the West Indies and standardized screening was carried out. Plasma renin activity (PRA) and serum aldosterone concentrations (SAC) were measured, followed by confirmatory intravenous saline suppression test. The patients were all women, of median age 48 years (interquartile range, IQR: 41-51.7 years). They tended to be overweight with suboptimal blood pressure control. Median serum potassium was 3.1 mmol/L (IQR 2.7 - 3.3 mmol/l) and kaliuresis was elevated or inappropriately normal. All individuals had suppressed PRA (< 0.6 ng/ml/hr) and elevated SAC (> 30 ng/dl), with SAC/PRA ratios > 50. Five patients had confirmed PH (ie post-saline SAC > 10 ng/dl); PH could not be definitely excluded in the sixth patient (ie post-saline SAC 5 - 10 ng/dl). Imaging studies revealed normal adrenal glands in one patient, unilateral adrenal enlargement in three patients, and unilateral adrenal masses in two patients. Only one of these latter two patients was shown to have an adrenal adenoma on histological examination. In this series, there appears to be fewer cases of the APA subtype of PH than expected. It remains to be seen whether the distribution of PH subtypes in Jamaica is actually different from elsewhere. This, and the cost-effectiveness of different approaches to screening, identification and management of patients suspected of having PH in Jamaica are areas for further study.