Safety of Frequent Venous Blood Sampling in a Pediatric Research Population

ObjectiveTo monitor hematological indices in otherwise healthy children with central precocious puberty who underwent frequent venous sampling as part of a longitudinal clinical research study.Study designThirty-four female subjects underwent frequent venous sampling (every 10-20 minutes for 8-16 hours) every 6 months for ≥3 years during and after their treatment with a gonadotropin-releasing hormone analogue. Hemoglobin (Hgb), mean corpuscular volume, and ferritin levels were measured before and after each phlebotomy session.ResultsAt baseline, the average Hgb level was 12.5 ± 0.7 g/L. At the conclusion of the first sampling session, the Hgb level fell 1.2 ± 0.1 g/L, remaining within the reference range for age. At the 3-month follow-up, there was complete recovery of Hgb (12.6 ± 0.2 g/L). Longitudinal evaluation every 6 months for as long as 3 years showed no significant differences in Hgb, mean corpuscular volume, or ferritin levels from baseline. No clinically significant adverse effects attributable to phlebotomy were reported.ConclusionWhen appropriate safety guidelines were followed, both acute and long-term frequent venous sampling in a pediatric population was safe. Guidelines include monitoring of hematological indices, phlebotomy volume <10 mL/kg/24 hours, and iron replacement.