Erythrocyte osmotic fragility in hypertension and during diuretic therapy.

To determine the effect of diuretic therapy on osmotic fragility of red blood cells of hypertensive patients, 25 hypertensive and 15 normotensive subjects were followed up for 12 weeks. Osmotic fragility of erythrocytes of the hypertensive subjects were determined before treatment and at 6 weeks and 12 weeks after the start of diuretic therapy. The red cell size was larger in hypertensive subjects than in normal controls. With treatment, however, the red cell size was similar in the two groups of subjects. Osmotic fragility was higher in hypertensive subjects than in normotensive subjects. The osmotic fragility also became similar in the two groups with control of blood pressure in the hypertensive group. Osmotic fragility of red blood cells may be determined as a screening tool for hypertensive patients who will benefit from diuretic therapy.