Progestogen-only pill associates with false-positive aldosterone/renin ratio screening test.

Aldosterone/renin ratio (ARR) is commonly used to screen for primary hyperaldosteronism (Conn's disease). A number of drugs can alter ARR measurements, thus requiring omission before testing. However, hormonal agents such as the combined oral contraceptive (COCP) or progestogen-only pill (POP) are not listed for omission. A 20-year-old woman was referred to the endocrinology team, following investigations for syncope by her cardiologist, when ARR was found to be elevated. She was taking POP (Cerelle) while having ARR measured. After omitting POP for four weeks, plasma aldosterone concentration was reduced by 52% (from 560 pmol/L to 271 pmol/L, reference range: 100-450 pmol/L), plasma renin concentration increased by 253% (from 3.6 mU/L to 12.7 mU/L, reference range: 5.4-30 mU/L) and ARR reduced from 156 to 21 (-86.5%) (reference range: <80 suggests Conn's unlikely). To the best of our knowledge, this is the first reported case of POP-related false-positive ARR screening for primary hyperaldosteronism. Omission of POP should, therefore, be considered in women undergoing ARR measurement.