Vitamin & Nutritional Testing Guide
Vitamin D, B12, folate, iron, ferritin, and magnesium — understanding nutritional deficiency blood tests.
What Is a Folate Blood Test?
Folate (folic acid) testing: essential for DNA synthesis and red cell production. Deficiency causes macrocytic anemia. Normal range 2-20 ng/…
What Is a Ferritin Blood Test?
Ferritin measures iron stores. Below 12 ng/mL = depleted. Below 20 = deficient. Best single marker of iron status. Also rises with inflammat…
What Is an RBC Magnesium Test?
RBC magnesium measures magnesium inside red blood cells — more accurate than serum magnesium for detecting total body depletion.…
What Is a Vitamin D 25-Hydroxy Test?
The 25-OH vitamin D test is the standard test for vitamin D status. It measures the storage form. Optimal: 30-50 ng/mL. Deficiency: below 20…
What Is a Methylmalonic Acid (MMA) Test?
MMA rises early in B12 deficiency — before serum B12 drops. Used when B12 is borderline (200-400 pg/mL) but symptoms suggest deficiency.…