Diuretic-induced hyponatremia and osteoporotic fractures in patients admitted to the emergency department.

OBJECTIVE: Hyponatremia is a complication of diuretic treatment and has been recently identified as a novel factor associated with osteoporosis and fractures. The impact of diuretic-associated electrolyte disorders on osteoporotic fractures (OF) has rarely been studied systematically.

DESIGN AND SETTING: We conducted a study in patients presenting to the emergency department at the University Hospital Bern. In this retrospective case series analysis of prospectively gathered data, over a 2-year period we identified 10,823 adult (≥50 years) outpatients with a measured baseline serum sodium, at admission to the hospital. OF patients were compared to a control group without fractures using standard statistical methods.

RESULTS: Four hundred and eighty (5%) patients had 547 OF. The OF group had a higher mean age (73 vs. 68 years, p<0.0001), smaller proportion of men (37% vs. 58%, p<0.0001), higher hospitalisation rate (83% vs. 62%, p<0.0001) and longer hospital stay (8 vs. 6 days, p<0.0001). Any diuretic agent (p<0.0001), loop diurietics (p=0.02), spironolactone (p=0.02) and amiloride (p<0.01) were used significantly more in OF patients, but not thiazides (p=0.68). The prevalence of hyponatremia increased significantly (p<0.0001) with the number of diuretics taken. Advanced age (odds ratio [OR] 1.04, p<0.0001), hyponatremia (OR 1.46, p=0.011) higher serum creatinine (OR 1.53, p=0.0001), furosemide use alone (OR 1.40, p=0.01) and co-treatment with amiloride (OR 2.22, p=0.02) were associated with a higher risk for OF.

CONCLUSIONS: This study highlights the clinical association of hyponatremia during the use of certain diuretics (i.e. furosemide or in combination, i.e. amiloride) with an increased risk of osteoporosis associated fractures. Although evidence-based data is currently lacking a pragmatic approach concerning hyponatremia monitoring and correction appears reasonable in selected groups of patients.