Effect of renal function on plasma levels of free and conjugated noradrenaline in patients with congestive heart failure - Comparison with patients with renal dysfunction

We measured plasma levels of free and conjugated noradrenaline in the antecubital vein at rest in 30 patients with cardiac diseases of NYHA class I, class II or class III, and in 20 patients with renal dysfunction. At the same time, we calculated creatinine clearance based on the plasma and urine creatinine levels and the 24-hour urine volume, and regarded the creatinine clearance as an index of renal function. Plasma noradrenaline levels were determined by high performance liquid chromatography with trihydroxyindole fluorimetric detection. Plasma levels of conjugated noradrenaline were measured as the plasma free form after deconjugation by heating the acidified plasma sample at 100°C. Plasma levels of free and conjugated noradrenaline increased from NYHA class I to class III in a stepwise manner. In contrast, creatinine clearance decreased from NYHA class I to class III in a stepwise manner. Plasma levels of free and conjugated noradrenaline were inversely correlated with creatinine clearance both in patients with heart failure and renal dysfunction. However, the regression line of patients with congestive heart failure was situated at a significantly higher position than that of patients with renal dysfunction. These results suggest that the elevated plasma level of conjugated noradrenaline seen in patients with congestive heart failure is due to decreased excretion from the kidney in addition to enhanced sympathetic nerve activity.