[Hyperuricemia as a marker for anaerobic threshold in chronic cardiac failure]

Patients with chronic cardiac failure often have elevated plasma uric acid levels, that are associated to a dismal prognosis.

To investigate possible metabolic mechanisms to explain elevated uric acid levels in these patients.

Eighteen patients with chronic cardiac failure aged 61 +/- 10 years old, without gout or renal failure and not using high doses of diuretics (equal or less than 80 mg/day furosemide or 50 mg/day hydrochlorothiazide) were studied. Plasma uric acid levels were correlated with anaerobic threshold, maximal oxygen uptake, plasma noradrenaline and creatinine and left ventricular ejection fraction, measured radioisotopically.

Mean maximal oxygen uptake was 16.6 +/- 4.2 ml/kg/min. There was a negative correlation between uric acid levels and maximal oxygen uptake or maximal oxygen uptake/body surface area (r = 0.521 and -0.533 respectively, p < 0.05). Patients with uric acid levels over 7 mg/dl had a lower anaerobic threshold than patients with lower levels (9.81 +/- 2.41 and 13.08 +/- 3.28 ml/kg/min respectively, p < 0.05). No significant differences in maximal oxygen uptake were observed in these two groups of patients (15.5 +/- 4.24 and 18.08 +/- 3.86 ml/kg/min respectively). Uric acid levels did not correlate with plasma noradrenaline, creatinine or left ventricular ejection fraction.

These results suggest that a defect in cellular oxygenation contributes to the elevation of plasma uric acid levels in patients with chronic cardiac failure.