Effect of low dose diuretics on plasma and blood cell electrolytes, plasma uric acid and blood glucose.

. The short-term effects of three diuretic drug regimens on plasma and blood cell electrolytes, plasma uric acid and blood glucose were studied in 11 subjects (aged 35–62 years) with mild hypertension in a double-blind cross-over study. Blood cell electrolytes were determined from hemolysed whole blood. The subjects were given 25 mg of hydrochlorothiazide (H), a combination of 25 mg of H and 2.5 mg of amiloride (HA) or a combination of 25 mg of H and 37.5 mg of triamterene (HT) once daily for 4 weeks in a randomized order. Plasma potassium fell slightly from 4.2–4.1 to 4.0–3.9 on each drug (significantly on H and HT, p < 0.05), the drop being most marked after one week. There were no statistically significant differences between the drug regimens. No changes were observed in plasma magnesium, calcium or sodium concentrations during the treatment periods. No statistically significant changes occurred in blood cell potassium or magnesium during any of the diuretic regimens. The increases in blood glucose during the treatment periods were minor, but this was statistically significant (p < 0.05) on HT. Plasma uric acid increased slightly but statistically significantly on each drug regimen (p < 0.05 on H and HA, p < 0.01 on HT). Three subjects who originally had normal or borderline uric acid values became clearly hyperuricaemic on each drug. All drug regimens decreased the systolic and diastolic blood pressure almost equally effectively. It is concluded that the 3 diuretic drug regimens had no clinically significant short-term effects on plasma electrolytes. However, it is probable that hyperuricaemia cannot be avoided in predisposed subjects even when diuretics are used in low doses.