Effects of phlebotomy-induced reduction of body iron stores on metabolic syndrome: Results from a randomized clinical trial (BMC Medicine)

Background: Metabolic syndrome (METS) is an increasingly prevalent but poorly understood clinical entity characterized by insulin resistance, glucose intolerance, dyslipidemia, hypertension and obesity. Increased oxidative stress catalyzed by accumulation of iron in excess of physiologic requirements has been implicated in the pathogenesis of METS but cause-and-effect relationships remain uncertain. The hypothesis that phlebotomy-induced reduction of body iron stores would alter clinical manifestations of METS was tested by a randomized trial. Methods: In a randomized-controlled single-blinded clinical trial 64 patients with METS were randomly assigned to iron reduction by phlebotomy (n=33) or to a waiting-list control group (n=31). Iron reduction patients had 300ml of blood removed at item and between 250-500ml removed after 4 weeks depending on item ferritin levels. Primary outcomes were change of systolic blood pressure and of insulin sensitivity as measured by HOMA-Index after 6 weeks. Secondary outcomes included HbA1c, plasma-glucose, blood lipids and heart rate. Results: Systolic blood pressure decreased from 148.5+/-12.3 mmHg to 130.5+/-11.8 mm Hg in the phlebotomy group and from 144.7+/-14.4 mmHg to 143.8+/-11.9 mmHg in the control group (difference -16.6 mmHg;95%-CI:-20.7;-12.5;p