Early onset of hyperkalemia in patients treated with low molecular weight heparin: A prospective study

Objective. Data on low molecular weight heparin (LMWH) and induction of hyperkalemia is scarce. Therefore, we conducted a prospective study evaluating potassium levels before and after three days of treatment with the LMWH Enoxaparin. Methods. Patients treated with the LMWH Enoxaparin in the standard therapeutic dosages were included. Levels of potassium, sodium, urea, creatinine, AST, ALT bicarbonate, pH and platelet counts were examined before and after three days of LMWH treatment. Plasma renin activity (PRA) and aldosterone levels were examined in a subgroup of patients. Potassium levels were correlated with disease states and medications known to affect potassium homeostasis. Results. Ninety-seven consecutive patients were enrolled in the study, however, 12 patients were excluded from analysis; therefore 85 patients comprised the study group. The most common reason for exclusion (in 9 patients) was the absence of a second potassium result. We found an increase in potassium levels from 4.26±0.04 mmol/L at baseline to 4.43 ± 0.04 mmol/L on the third day of treatment (mean ± SE), with potassium levels exceeding 5.0 mmol/L in 9% of treated patients. There was no life threatening or symptomatic hyperkalemia. PRA and aldosterone levels did not change significantly during the treatment period. There was no correlation between the increase in potassium levels and diabetes mellitus or treatment with angiotensin converting enzymes inhibitors, angiotensin receptor blockers, β-blockers and non-potassium sparing diuretics. Conclusions. Potassium levels increase on the third day of treatment with the LMWH Enoxaparin. This effect may be aldosterone independent.