DETERMINATION OF THE BLOOD LACTATE-PYRUVATE RATIO AS A NONINVASIVE TEST FOR THE DIAGNOSIS OF ZIDOVUDINE MYOPATHY

Objective. To evaluate the use of the lactate: pyruvate ratio as a tes t for the detection of zidovudine myopathy. Methods. Twenty consecutiv e human immunodeficiency virus-infected patients with muscle involveme nt and 20 without muscle involvement were studied prospectively. Blood lactate and pyruvate levels and serum creatine kinase levels were tes ted, muscle involvement was assessed both clinically and electrophysio logically, and muscle biopsy was performed in patients with myopathy. Results. Nine patients had biopsy-proven zidovudine myopathy. All 9 ha d a high lactate:pyruvate ratio, with elevations on 2 of 2 determinati ons in 6 patients and on 1 of 2 in 3 patients. Two of 11 patients with other myopathies and 2 of 20 patients without myopathy had a high lac tate:pyruvate ratio on 1 of 2 determinations. Conclusion. The lactate: pyruvate ratio, when determined repeatedly, is a sensitive test for de tecting mitochondrial muscular toxicity of zidovudine.