Hypouricemia in Acquired Immunodeficiency Syndrome

Clinical evaluations of hypouricemia in patients with the acquired immunodeficiency syndrome (AIDS) have shown that it is a common disorder resulting from defective renal handling of uric acid. We prospectively studied renal urate handling in 23 patients and reviewed the records of 73 consecutive patients with AIDS or AIDS-related complex (ARC), who were seen in our AIDS clinic between March 1985 and April 1988, to determine the incidence, significance, and, when possible, the cause of hypouricemia. Hypouricemia was defined as serum urate < 0.18 mmol/L (3 mg/dL). Renal clearance studies were performed in 23 patients, 10 hypouricemic and 13 nonhypouricemic. Eight patients (six with hypouricemia) underwent central venous pressure (CVP) monitoring, which was performed for clinical signs and symptoms of extracellular volume depletion. Fourteen (eight with hypouricemia) had daily urine urate measured. Hypouricemia was found in 21 (21.9%) of 96 patients. It was more common in females and intravenous (IV) drug abusers, and was associated with more opportunistic illnesses, particularly mycobacterium avium intracellulare (MAI) and cytomegalovirus (CMV) infections. Hypouricemia occurred in three patients with ARC and 18 patients with AIDS and was associated with cerebral atrophy in all 12 hypouricemic and 14 of 28 nonhypouricemic patients who had cranial computed tomography (CT) scans. During a comparable follow-up period, 71.4% of the hypouricemic as compared with 38.7% of nonhypouricemic patients died. Eleven developed hyouricemia as outpatients. Fractional excretion of uric acid (FEua) was elevated in the eight patients with CVP < 1 cm of water, and in 10 of 10 with and nine of 13 without hypouricemia, despite CVP < 1 cm water in eight. Daily urate excretion was normal or elevated in the 14 patients studied. None of the medications the patients received during the period of study could account for the renal urate transport defect. Hypouricemia is common in patients with AIDS and ARC, is associated with higher morbidity and mortality rates, does not appear to be a terminal event, and appears to be due to a renal urate transport defect.