Phlebotomy (bloodletting) in patients with metabolic syndrome: A randomized controlled trial

Abstract

Question Metabolic syndrome has an increasing prevalence worldwide and there is an urgent need for improvement of medical treatment. In traditional medical systems bloodletting is a frequently recommended therapy in subjects with obesity and vascular disease. Recent randomized studies showed that bloodletting improves insulin sensitivity in patients with diabetes mellitus and increased ferritin concentration and might be beneficial in younger patients with peripheral arterial vascular disease. We aimed to test if traditional bloodletting has beneficial effects in patients with metabolic syndrome. Methods A randomized controlled study with a study period of 3 months was conducted in 64 self-referred subjects that had a confirmed diagnosis of metabolic syndrome as defined by recent guidelines. Thirty-three subjects (60±7 yr; BMI 32.8±5.5 kg/m 2 ) were allocated to the bloodletting intervention group and 31 subjects (57±10 yr; BMI 32.5±5.6 kg/m 2 ) to the control group (waiting list). In the intervention group two phlebotomies with removal of 300–400 ml of venous blood were performed at day 1 and after 4 weeks. Primary outcomes were the course of seated systolic blood pressure and of insulin sensitivity as measured by HOMA-Index. Secondary endpoints included diastolic blood pressure, ferritin, serum iron, hematocrit, HbA1c, LDL/HDL-quotient and blood glucose. Results Baseline characteristics were balanced between groups. Seated systolic blood pressure dropped from 148.5±12.3 to 130.5±11.8 mmHg in the intervention group and from 144.7±14.4 to 143.8±11.9 mmHg in the control group (group difference −16.6 mmHg, 95% CI:−20.7 to −12.5; p p =0.251). Diastolic blood pressure, heart rate, blood glucose, HbA1c and LDL/HDL were significantly decreased by bloodletting. Bloodletting led to reductions of serum iron concentration, plasma ferritin and a slight decrease in hematocrit with no serious adverse events. Conclusions Phlebotomy (bloodletting) effectively decreases blood pressure and improves metabolic parameters in patients with metabolic syndrome. Larger studies should test the longer-term efficacy of bloodletting in metabolic syndrome, hypertension and lipid disorders.