Background: The prevalence of primary hyperaldosteronism (PA) has recently been reported as high as 7.5% in patients with hypertension from unselected populations (USP) and up to 22% in selected populations (SP). Whether increased screening and diagnosis of PA will lead to more findings of curable PA (aldosterone producing adenoma, APA) is unclear.
Methods: Three-hundred fifty-three consecutive patients with hypertension, age 20 to 88 years were included from two primary care centers (230 USP) and specialized university hypertension outpatient clinics (123 SP) in the same catch-up area. Plasma renin activity and serum aldosterone levels were sampled. Patients with criteria for PA did positional and salt-loading test for confirmation. Further investigation was with CT-adrenals, 131I-chol-scintigraphy and adrenal vein sampling (AVS), with few exceptions. The local ethical committee approved the study.
Results: Forty-six patients, 28 SP (22.8%) and 18 USP (7.8%), had criteria for PA. Six USP and 22 SP were available for further investigation. Confirmation tests found 8 patients to be normal. Nine of eighteen (53%) CT-adrenals had positive findings. Three of 17 (18%) 131I-chol-scintigraphies had positive findings. Ten of 14 AVS (71%) had positive findings. Four AVS were unsuccessful. Supplementary information from 131I-chol-scintigraphy and CT-adrenals lead to clear diagnosis in 3 of them, 1 AH and 2 APA. Further investigation after screening lead to clear diagnosis in 27 of 28 (96%) patients, 8 AH, 11 APA.
Conclusion: The study confirms high prevalence of PA found in recent studies, higher in SP than USP as expected. Our results indicate that screening for PA finds more patients with curable cause of PA. All APA were from the SP group. Our findings indicate that 131I-chol-scintigraphy is less accurate for diagnosing APA than CT-adrenals and that the AVS is superior to both of them, further comparison of the methods are needed.