M E Jensen1, F M Ducharme2, Y Théorêt3, A-S Bélanger4, E Delvin5. 1. Centre for Asthma and Respiratory Diseases, School of Biomedical Sciences, School of Medicine and Public Health, University of Newcastle, Callaghan, Australia. 2. Departments of Pediatrics and Social and Preventive Medicine, University of Montreal, Canada; Clinical Research and Knowledge Transfer Unit, Research Centre, CHU Ste-Justine, Montreal, Canada. 3. Clinical Pharmacology Unit, Department of Clinical Biochemistry, CHU Ste-Justine, Canada; Department of Pharmacology, University of Montreal, Canada. 4. Department of Clinical Biochemistry, CHU Ste-Justine, Canada. 5. Gatroenterology, Hepatology & Nutrition Division, CHU Ste-Justine Research Centre, University of Montreal, Canada. Electronic address: delvine@sympatico.ca.
Abstract
BACKGROUND: Venous blood is the usual sample for measuring various biomarkers, including 25-hydroxyvitamin D (25OHD). However, it can prove challenging in infants and young children. Hence the finger-prick capillary collection is an alternative, being a relatively simple procedure perceived to be less invasive. We elected to validate the use of capillary blood sampling for 25OHD quantification by liquid chromatography tandem-mass spectrometry (LC/MS-MS). METHODS: Venous and capillary blood samples were simultaneously collected from 15 preschool-aged children with asthma 10days after receiving 100,000IU of vitamin-D3 or placebo and 20 apparently healthy adult volunteers. 25OHD was measured by an in-house LC/MS-MS method. RESULTS: The venous 25OHD values varied between 23 and 255nmol/l. The venous and capillary blood total 25OHD concentrations highly correlated (r(2)=0.9963). The mean difference (bias) of capillary blood 25OHD compared to venous blood was 2.0 (95% CI: -7.5, 11.5) nmol/l. CONCLUSION: Our study demonstrates excellent agreement with no evidence of a clinically important bias between venous and capillary serum 25OHD concentrations measured by LC/MS-MS over a wide range of values. Under those conditions, capillary blood is therefore adequate for the measurement of 25OHD.
BACKGROUND: Venous blood is the usual sample for measuring various biomarkers, including 25-hydroxyvitamin D (25OHD). However, it can prove challenging in infants and young children. Hence the finger-prick capillary collection is an alternative, being a relatively simple procedure perceived to be less invasive. We elected to validate the use of capillary blood sampling for 25OHD quantification by liquid chromatography tandem-mass spectrometry (LC/MS-MS). METHODS: Venous and capillary blood samples were simultaneously collected from 15 preschool-aged children with asthma 10days after receiving 100,000IU of vitamin-D3 or placebo and 20 apparently healthy adult volunteers. 25OHD was measured by an in-house LC/MS-MS method. RESULTS: The venous 25OHD values varied between 23 and 255nmol/l. The venous and capillary blood total 25OHD concentrations highly correlated (r(2)=0.9963). The mean difference (bias) of capillary blood 25OHD compared to venous blood was 2.0 (95% CI: -7.5, 11.5) nmol/l. CONCLUSION: Our study demonstrates excellent agreement with no evidence of a clinically important bias between venous and capillary serum 25OHD concentrations measured by LC/MS-MS over a wide range of values. Under those conditions, capillary blood is therefore adequate for the measurement of 25OHD.