Interpreting combinations of methylmalonic acid and homocysteine level results

Mental health clinicians often check serum vitamin B12 levels, especially in patients with cognitive impairment or nutritional deficiency, and in patients who are vegetarian or vegan. The test that laboratories use to measure vitamin B12 levels has some limitations. So, if the vitamin B12 level is low-normal, we cannot rule out vitamin B12 deficiency. When…