Aim: Study aim was to investigate the effects of therapeutic phlebotomy on ambulatory blood pressure in patients with grade 1 hypertension. Methods: In this randomized-controlled intervention study, patients with unmedicated hypertension grade 1 were randomized into an intervention group (phlebotomy group; 500 mL bloodletting at baseline and after 6 weeks) and a control group (waiting list) and followed up for 8 weeks. Primary endpoint was the 24-h ambulatory mean arterial pressure between the intervention and control groups after 8 weeks. Secondary outcome parameters included ambulatory/resting systolic/diastolic blood pressure, heart rate, and selected laboratory parameters (e.g., hemoglobin, hematocrit, erythrocytes, and ferritin). Resting systolic/diastolic blood pressure/heart rate and blood count were also assessed at 6 weeks before the second phlebotomy to ensure safety. A per-protocol analysis was performed. Results: Fifty-three hypertension participants (56.7 ± 10.5 years) were included in the analysis (n = 25 intervention group, n = 28 control group). The ambulatory measured mean arterial pressure decreased by -1.12 ± 5.16 mmHg in the intervention group and increased by 0.43 ± 3.82 mmHg in the control group (between-group difference: -1.55 ± 4.46, p = 0.22). Hemoglobin, hematocrit, erythrocytes, and ferritin showed more pronounced reductions in the intervention group in comparison with the control group, with significant between-group differences. Subgroup analysis showed trends regarding the effects on different groups classified by serum ferritin concentration, body mass index, age, and sex. Two adverse events (AEs) (anemia and dizziness) occurred in association with the phlebotomy, but no serious AEs. Conclusions: Study results showed that therapeutic phlebotomy resulted in only minimal reductions of 24-h ambulatory blood pressure measurement values in patients with unmedicated grade 1 hypertension. Further high-quality clinical studies are warranted, as this finding contradicts the results of other studies.
Keywords: bloodletting; complementary medicine; hypertension; phlebotomy.