Effect of low-molecular-weight heparin on potassium homeostasis.
BACKGROUND
Low-molecular-weight heparins (LMWHs) are being preferred to unfractionated heparin (UFH) because of their superior convenience and a comparable or slightly better toxicity profile. Whether LMWH has an inhibitory effect on aldosterone that causes hyperkalemia is yet uncertain.


METHODS
Twenty-eight patients (all male; mean age: 70 years, range 52-87 years) placed on LMWH therapy (40 mg subcutaneously every 12 h) for deep venous thrombosis prophylaxis after an operation were included in the study. Transtubular potassium concentration gradient (TTKG) was calculated 1 day prior to LMWH therapy and again after 4 days of treatment. Of the 28 patients enrolled in the study, we were able to calculate the TTKG in only 19 patients: 9 had a urinary osmolarity (either before or after LMWH therapy) less than the serum osmolarity, making the TTKG calculation unreliable. The Wilcoxon signed-rank test was used to analyze differences in the median serum potassium levels and TTKG before and after LMWH therapy.


RESULTS
All patients had adequate renal function (creatinine clearance >90 ml/min). Mean (+/- SD) serum potassium concentration before LMWH was 4.25 (+/- 0.40) mmol/dl. It increased to 4.35 (+/- 0.41) mmol/dl after initiating LMWH therapy (p = 0.09). Similarly, the mean (+/- SD) TKKG calculated was 5.52 (+/- 2.33) before and 5.97 (+/- 3.06) after 4 days of LMWH (p = 0.54).


CONCLUSIONS
Unlike UFH, LMWH (Lovenox in doses used for postoperative prophylaxis against deep venous thrombosis does not seem to have a significant effect on potassium homeostasis.
Abdel-Raheem
Majdi  M
M
Department of Medicine, University of North Dakota School of Medicine, Fargo, N Dak 58102, USA.
Potti
Anil
A
Tadros
Sherine
S
Koka
Vijay
V
Hanekom
David
D
Fraiman
Genise
G
Danielson
Byron D
BD
D000368:Aged; D000369:Aged, 80 and over; D000450:Aldosterone / Q000502:physiology*; D003404:Creatinine / Q000378:metabolism; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects / Q000494:pharmacology*; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D006947:Hyperkalemia / Q000097:blood / Q000139:chemically induced / Q000652:urine; D007684:Kidney Tubules / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D009994:Osmolar Concentration; D011183:Postoperative Complications / Q000517:prevention & control; D011188:Potassium / Q000378:metabolism*; D020246:Venous Thrombosis / Q000517:prevention & control; D015384:Zona Glomerulosa / Q000187:drug effects
D006495:Heparin, Low-Molecular-Weight; D000450:Aldosterone; D003404:Creatinine; D011188:Potassium