IMPROVEMENT IN EXERCISE TOLERANCE IN ISOVALERIC ACIDEMIA WITH L-CARNITINE THERAPY

The effect of 4 weeks' treatment with oral-L-carnitine (100 mg/kg per day) on carnitine status and metabolic parameters during an incrementa l ramp exercise test in a 12-year-old girl with isovaleric acidaemia w as examined to determine its possible therapeutic role. The maximum wo rk rate achieved increased from 110 to 120 watts; oxygen consumption a t anaerobic threshold from 600 to 800 L/min; peak oxygen consumption f rom 1270 to 1450 L/min; and oxygen pulse, a measure of cardiac output, from 7.0 to 8.1 L/beat. These changes were associated with increases in plasma and urinary free and acyl carnitine concentrations but no ch ange in physical activity. This observed effect of L-carnitine on exer cise performance may be on cardiac or skeletal muscle function or both . We conclude that, in this single patient with isovaleric acidaemia, L-carnitine supplementation had objective benefits and further studies on more patients are warranted.