Background and Importance Loop diuretics and thiazides are commonly known to cause hypokalaemia. Several cases of hypokalaemia were discovered in patients undergoing diuretic treatment during pharmaceutical validation.

Aim and Objectives Main objective was to study the risk of hypokalaemia in hospitalised patients receiving ≥2 diuretics.

Material and Methods A descriptive and retrospective study was designed. The number of admissions treated with diuretics from August 2022 to July 2023 were extracted from electronic prescription software (Dominion FarmaTools®) and potassium blood levels from laboratory software (Modulab®).

The outcome was the proportion of included patients with hypokalaemia. Inclusion criteria: ≥2 diuretics for ≥2 consecutive days with ≥2 serum potassium levels. Assessed diuretics were: furosemide (F), hydrochlorothiazide (H), eplerenone (E) and spironolactone (S). Assessed potassium supplement (PS) were: potassium hydrogencarbonate and potassium chloride.

‘Diuretic-associated hypokalaemia’ was defined as potassium level <3.5mEq/dL at least two days after initiating treatment with ≥2 diuretics. Additionally, PS were also collected from admissions with hypokalaemia.

Results A total of 4,127 registers of patients admitted with diuretic treatment were initially reviewed, 988 had ≥2 concomitant diuretics and 517 of them were prescribed for ≥2 days.

Hypokalaemia was identified in 40.8% of patients admitted. Loop diuretic combined with either S or E had similar hypokalemic rates (42,7%; 41,4% respectively) but not as high as when combined with H(59.4%).

In addition, PS had to be added to 124(58.8%) of patients that developed hypokalaemia.

Conclusion and Relevance Almost half of admissions with combination of diuretics developed hypokalaemia due to these drug combination.

F was involved in every treatment. F + H was the combination more commonly associated with hypokalaemia (risk difference 25.4%;IC95 15.9–34.9 vs the rest of associations).

The combination of loop and potassium-sparing diuretics also leads to hypokalaemia despite S or E.

More than half of admissions required the addition of PS. Potassium levels should be monitored regularly in all patients receiving diuretic treatment with ≥2 drugs.

Conflict of Interest No conflict of interest.