How is Conns syndrome (primary hyperaldosteronism) diagnosed?
Conn’s syndrome should be suspected in all patients with high blood pressure. Traditional teaching has been to limit investigation for Conn’s syndrome to patients who have a low blood potassium, or in whom blood pressure which is moderate to severe (>160/110mmHg), or is difficult to control with medication. However, using these criteria, many patients with Conn’s syndrome will not be diagnosed. For example, about 40 per cent of patients with proven Conn’s syndrome have normal blood potassium levels. The most rigorous method of diagnosis is to measure the blood levels of two hormones: aldosterone and renin (which plays a role in stimulating aldosterone production). In Conn’s syndrome, the aldosterone level is elevated and the renin level is low or undetectable.
