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Diuretics and electrolyte disturbances in 1000 consecutive geriatric admissions
C M Byatt1, P H Millard, G E Levin
1Department of Geriatric Medicine, St George's Hospital Medical School, London.
Insights
Diuretic use in older adults is common and linked to lower serum sodium levels. While potassium-sparing diuretics were associated with higher potassium, specific risks of co-amilozide were not significantly higher.
Area of Science:
- Geriatric Medicine
- Clinical Pharmacology
- Nephrology
Background:
- Diuretics are frequently prescribed for elderly patients.
- Electrolyte disturbances are a known risk of diuretic use.
- Controversy exists regarding the comparative risks of different diuretic combinations, such as co-amilozide.
Purpose of the Study:
- To investigate the association between diuretic prescription and serum electrolyte levels in elderly hospital admissions.
- To examine the relative prescribing rates of various diuretics in the community.
- To assess the specific risks of co-amilozide compared to other diuretics.
Main Methods:
- Retrospective analysis of drug history and serum electrolytes in 929 elderly patients.
- Comparison of electrolyte levels between patients prescribed diuretics and those not.
- Examination of prescribing rates of different diuretic classes in the community.
Main Results:
- 38% of patients had a history of diuretic use, with significantly lower mean serum sodium compared to non-users.
- Hyponatraemia was not more common in patients taking co-amilozide than other diuretics.
- Potassium-sparing diuretics were associated with lower serum sodium, while loop or thiazide diuretics were associated with lower serum potassium.
Conclusions:
- Diuretic use is associated with lower serum sodium in the elderly.
- The risk of hyponatraemia with co-amilozide was not significantly greater than with other diuretics.
- Interactions between diuretic type and serum potassium levels were observed and appeared independent and additive.
Abstract:
Old people are commonly receiving diuretics on admission to hospital. Diuretics are recognized as a risk factor for electrolyte disturbances; controversy exists about the relative risks of different combinations (in particular, co-amilozide [Moduretic]). We recorded the drug history and serum electrolytes in 1000 consecutive admissions to a geriatric hospital, and examined the relative prescribing rates of various diuretics in the community. Full results were obtained in 929 patients. A history of diuretic prescription was present in 353 (38%) of the patients; the mean serum sodium in this group (95% CI 136.0-137.1 mmol/l) was lower than in the 586 not prescribed diuretics (137.1-137.9 mmol/l). The difference was small but statistically significant (95% CI difference = 0.3-1.6 mmol/l; P less than 0.01). Hyponatraemia (serum sodium less than 130 mmol/l) was not significantly commoner in the 41 patients prescribed co-amilozide than in patients prescribed other diuretics. In general patients prescribed potassium-retaining diuretics had a lower serum sodium than the others. There was a significant positive correlation between the serum potassium and the log [serum urea] (r = 0.26, P less than 0.001) and a weak negative correlation existed between sodium and potassium (r = -0.14; P less than 0.001). There was an association between the prescription of potassium-retaining diuretics and a higher serum potassium; also an association between the prescription of a loop or thiazide diuretic and a lower serum potassium. These interactions were shown by multiple regression analysis to be independent and additive.(ABSTRACT TRUNCATED AT 250 WORDS)