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.

Hyperhomocysteinemia and the risk of thromboembolic phenomenon in patients with chronic renal failure.

Thromboembolic phenomena are a major cause of morbidity and mortality in patients with end-stage renal disease. Studies in patients with chronic renal failure (CRF) have demonstrated an increased relative risk of coronary artery disease (CAD) in association with hyperhomocysteinemia (HHe). However, very little data exist about the causal relationship between HHe and cerebrovascular diseases (CVA) in patients with CRF. We report the results of our observational retrospective study to determine the effect of HHe on CVA and CAD in patients with CRF (defined as creatinine clearance <50 ml/min). One hundred ten male patients were eligible for our study performed at a Veterans Affairs Medical Center. Age range was 36-86 years (median age 67 years). A fasting plasma HC level >15 micromol/l was considered as HHe. Thirty-four patients were on dialysis. Eight patients were postrenal transplantation. Our study results showed that a homocysteine (HC) level greater than 15 micromol/l was an independent predictor of CVA, after adjusting for potential confounders. Adjusted odds ratio (OR) for CVA was 10.9 (CI: 1.8-67.2, p=.01). Although our study results suggest a strong relationship between HHe and CVA, they failed to demonstrate an association between HHe and CAD. There exists a need for larger prospective randomized clinical trials to evaluate the effect of HHe on the incidence of CVA and CAD in patients with CRF.