gms | German Medical Science

Background: A considerable number of geriatric patients are affected by electrolyte disorders, which may, not infrequently, lead to serious health consequences such as hospitalization. Many of these patients are treated with diuretics [1]. The objective of this study was to investigate whether diuretic therapy alone or in combination with additional risk factors is associated with electrolyte disturbances in elderly inpatients.

Materials and Methods: Prospective study of consecutive patients admitted to a geriatric hospital between January 9th, 2011 and November 8th, 2011. Primary endpoint was the incidence of hyponatraemia and hypokalaemia. Patients suffering from electrolyte disorders were examined for clinical symptoms such as delirium, falls, dehydration, hypotension and renal impairment.

The causal relationship between diuretic therapy and electrolyte disturbances and/or the above mentioned symptoms was assessed using the Naranjo algorithm [2]. By means of logistic regression analysis (IBM SPSS 23) the impact of various independent risk factors on the primary end-point hyponatraemia (Na concentration < 134mmol/l) and hypokalaemia (K concentration < 3.5 mmol/l) as well as on the secondary end-point dehydration was analysed.

Results: 948 patients with a median age of 83 years (range:79-88 years) were included; 687 (72,5%) of them were female gender; and 595 (62,8%) used at least one diuretic. Dehydration (OR 4,645; 2,847 – 7,578; p<0,001), severe heart failure (OR 1,842; 1,043 – 3,255; p=0,035) and a reduced hand grip strength (OR 1,561; 1,035 – 2,355; p=0,034) had a significant influence on sodium disorders, whereas malnutrition as defined by the Mini Nutritional Assessment short form (OR 0,898; 0,84 – 0,96; p=0,001) and dehydration (OR 1,933; 1,198 – 3,12; p=0,007) had a significant impact on potassium disorders.

The use of diuretics (OR 1,944; 1,165 – 3,245; p=0,011) , reduced renal function (OR 0,977; 0,966 – 0,988; p<0,001), malnutrition (OR 0,858; 0,789 – 0,932; p<0,001) and diarrhea/vomiting (OR 7,02; 4,112 – 11,983; p<0,001) had a significant influence on the development of dehydration.

Electrolyte disturbances and dehydration could be classified as definite or probable adverse drug reactions in almost half of the cases. The other symptoms were predominantly described as possible adverse drug reactions.

The combination of loop diuretics with thiazide diuretics seemed to cause hypokalaemia or hyponatraemia more frequently in women than in men.

Conclusion: In agreement with the existing literature the influence of diuretics on the development of dehydrations, which in turn are associated with electrolyte disturbances, could be demonstrated [3]. Therefore diuretic therapy in elderly patients requires frequent monitoring, which is not mentioned in current guidelines. The twice yearly check of the glomerular filtration rate as suggested by the current DEGAM guideline [4] does not address diuretic-induced adverse drug events in elderly patients. The tendency towards a higher vulnerability of women with regard to diuretic associated disturbances has already been observed by other authors and is obviously not related to a higher prevalence of diuretic prescriptions [5].