Acute gout after initiation of bendroflumethiazide

A 70-year-old man presented to the medical outpatient clinic with acute pain, swelling and redness in his left first metatarsophalangeal joint, consistent with acute gout. He reported that the pain started suddenly two days ago, waking him at night. On examination, the joint was exquisitely tender, swollen, erythematous, with desquamation of the overlying skin. His temperature was 37.8°C. His past medical history included hypertension, for which he had been taking bendroflumethiazide 2.5 mg daily, lisinopril 10 mg daily, and amlodipine 5 mg daily. He had been on lisinopril and amlodipine for several years, but bendroflumethiazide was started two months ago after a review of his blood pressure. He had no family history of gout, and had never had a similar episode before. He reported drinking about 14 units of alcohol per week, which he had not changed recently. He had a mild upper respiratory tract infection about two weeks ago, which had resolved without antibiotics. Laboratory investigations showed an elevated serum uric acid of 0.52 mmol/L (normal range: 0.20–0.42 mmol/L), an elevated C-reactive protein of 22 mg/L, and a normal renal function (creatinine 95 µmol/L, eGFR 74 mL/min/1.73m²). His full blood count was normal. His medications were continued initially, but his symptoms worsened over the next two days despite conservative management. He was started on colchicine 0.5 mg twice daily, which resolved his symptoms over the following week. After discharge from clinic, his bendroflumethiazide was stopped, and his serum uric acid fell to 0.41 mmol/L three weeks later. He had no further episodes of gout. He was rechallenged with bendroflumethiazide 2.5 mg daily four months later, and within six weeks he experienced a second attack of gout affecting the same joint, which again resolved after stopping the bendroflumethiazide and a course of colchicine.