Díaz Lab Testing Store › Folate B9 | Serum (Quest) Image 1 of 1 Folate B9 | Serum (Quest) $27.00 Measures folate status — essential for methylation, DNA repair, red blood cell production, and pregnancy health. Add To Cart Added! Measures folate status — essential for methylation, DNA repair, red blood cell production, and pregnancy health. Add-on | Interpretation for Individual Markers $17.00 Add Added!