A patient with vitamin B12 deficiency may show a number of clinical and laboratory findings.

NOTE: It is important to distinguish those findings attributable to the vitamin B12 deficiency from those associated with the underlying cause of the deficiency.


General findings include:

(1) fatigue and general weakness

(2) glossitis

(3) stomatitis

(4) pallor

(5) loss of appetite with weight loss

(6) mild jaundice

(7) loss of central vision


Psychiatric findings may include:

(1) confusion

(2) neurosis

(3) delusions and/or hallucinations

(4) memory loss

(5) dementia

(6) stupor


Neurologic findings (associated with deterioration in the posterior and lateral columns of the spinal cord)

(1) paresthesias in hands and feet

(2) decreased vibration and position senses (proprioception)

(3) decreased deep tendon reflexes

(4) ataxia with unsteady gait


Laboratory findings may include:

(1) megaloblastic anemia, with elevated MCV

(2) thrombocytopenia and/or neutropenia

(3) elevated serum total bilirubin (due to indirect bilirubin)

(4) elevated serum LDH


Diagnostic tests:

(1) methylmalonic acid (MMA) in serum or urine

(2) serum vitamin B12


Neurologic changes associated with vitamin B12 deficiency may occur in the absence of megaloblastic anemia.

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