Folate, Serum

Serum Folate (Vitamin B9) measures the level of folate circulating in the blood. Folate is crucial for DNA synthesis and repair, red blood cell production, and methylation reactions (working with B12). Deficiency causes megaloblastic anemia and elevated homocysteine, and is critical to prevent during pregnancy to avoid neural tube defects. Serum folate reflects recent intake. RBC Folate is a better marker of long-term stores. Optimal serum levels are generally well above the deficiency threshold (e.g., >10-15 ng/mL).