Variability of heparin levels and bleeding with low-dose heparin prophylaxis following transurethral resection of the prostate.

Plasma heparin levels and operative/postoperative bleeding were assessed in 16 patients of varying body weights who received subcutaneous low-dose heparin prophylaxis for deep vein thrombosis during and after transurethral resection for benign prostatic hypertrophy. The concentration of heparin in the blood at operation and subsequently was found to vary widely but did not correlate with the extent of blood loss. When adjusted for body weight, plasma heparin concentration showed significantly less variation from patient to patient. In this respect, body weight was a more effective parameter than lean body mass or surface area. Adjustment of heparin dosage by body weight may be advisable when using low-dose heparin prophylaxis.