No influence of furosemide on human erythrocyte shape and volume and blood viscosity in vitro

Furosemide is a diuretic agent which is often given in high concentrations intravenously. Since erythrocytes have a furosemide‐sensitive transport system and oral application of furosemide was found to induce an echinocytic shape transformation in horses, we have analysed the influence of furosemide on erythrocyte shape, volume and blood viscosity in vitro. Increasing plasma furosemide concentrations of 0, 1, 10, 100 and 1000 $\mu$ g/ml did not affect the erythrocyte volume or shape and left blood viscosity unaffected. We conclude that furosemide has no influence on blood rheology in humans.