1. Date of download: 6/21/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Laboratory Diagnosis of Vitamin B12 and Folate Deficiency: A Guide for the Primary Care Physician Arch Intern Med. 1999;159(12):1289-1298. doi:10.1001/archinte.159.12.1289 Conversion of methylmalonyl–coenzyme A (CoA) to succinyl-CoA. Ado-Cbl indicates adenosyl-cobalamin. Figure Legend:

2. Date of download: 6/21/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Laboratory Diagnosis of Vitamin B12 and Folate Deficiency: A Guide for the Primary Care Physician Arch Intern Med. 1999;159(12):1289-1298. doi:10.1001/archinte.159.12.1289 Synthesis of methionine from homocysteine. Cbl indicates cobalamin. Figure Legend:

3. Date of download: 6/21/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Laboratory Diagnosis of Vitamin B12 and Folate Deficiency: A Guide for the Primary Care Physician Arch Intern Med. 1999;159(12):1289-1298. doi:10.1001/archinte.159.12.1289 Approach to the patient with hematologic abnormalities and a serum cobalamin (Cbl) level less than 74 pmol/L (100 pg/mL). The asterisk indicates that the complete blood cell count of patients treated with oral or intramuscular Cbl should be monitored until the hematologic abnormalities are corrected completely; if the initial serum folate level is low, it is prudent to administer folic acid in addition to Cbl. Figure Legend:

4. Date of download: 6/21/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Laboratory Diagnosis of Vitamin B12 and Folate Deficiency: A Guide for the Primary Care Physician Arch Intern Med. 1999;159(12):1289-1298. doi:10.1001/archinte.159.12.1289 Evaluation of neurologic symptoms and signs suggestive of possible cobalamin (Cbl) deficiency in patients with normal complete blood cell counts. Symptoms include paresthesias, ataxia, mental status changes, and vibratory and position sense impairment. MMA indicates methylmalonic acid; Hcy, homocysteine. Figure Legend: