A new preanalytical procedure using dried blood spot sample for total homocysteine determination

Abstract number: P0443

Campolo^* J., Caruso^* R., Parolini^* M., Melotti† D., Corbetta† C., Bigi^* R., Parodi^* O., Accinni^* R.

^*CNR Clinica Physiology Institute, Italy; †Neonatal Screening Laboratory, Italy

Background and aim  

Determination of total homocysteine (tHcy) plasma level requires a critical preanalytical phase that can cause false positive results. tHcy is produced and released by blood cells and its plasma level can increase up to 10% per hour unless immediate centrifugation is done to get optimal separation. To overcome this problem, we introduced a new analytical approach using dried blood spots on paper screening cards. This study assesses the reproducibility between dried spot and plasma sample method to dose tHcy.

Methods  

tHcy was determined on blood samples obtained from 39 normal and 24 hyperhomocystinemic subjects, aged 1–75 years, using both analytical methods. Paper disks containing blood spots were reduced and derivatized in only one step before HPLC analysis with fluorimetric detection. Reproducibility was assessed by the Bland–Altman's plot method.

Results  

Mean tHcy was 10.65 ± 8.84 mmol L^-1 (range 3–58 mmol L^-1) in plasma and 9.65 ± 7.83 mmol L^-1 (range 3–5 mmol L^-1) in dried blood spots, respectively. A reproducibility coefficient of 2.01 mmol L^-1 included the 95% of the observed difference between the two groups of determinations.

Conclusions  

These preliminary results suggest that this new preanalytical procedure may be of help in solving problems associated with sample withdrawal and storage and may be proposed as an alternative method for tHcy assay.