What are the physical exam findings of a vitamin B12 deficiency?

Physical Examination Findings of Vitamin B12 Deficiency

The key physical examination findings of vitamin B12 deficiency include neurological manifestations (peripheral neuropathy, ataxia, impaired gait), glossitis, optic nerve dysfunction, and signs of anemia, which should prompt immediate testing and treatment to prevent irreversible neurological damage.

Neurological Findings

• Balance issues and falls caused by impaired proprioception linked to sensory ataxia, which may result from spinal cord damage 1, 2
• Impaired gait and mobility problems related to peripheral neuropathy or central nervous system disease including myelopathy 1, 3
• Symmetric paresthesia (pins and needles or numbness) indicating peripheral nerve damage 1, 2
• Cognitive difficulties, including difficulty concentrating and short-term memory loss (sometimes described as "brain fog") 1, 3
• Personality changes affecting the central nervous system 2

Ophthalmologic Findings

• Blurred vision related to optic nerve dysfunction 1, 2
• Optic atrophy on fundoscopic examination 1, 3
• Visual field loss (scotoma) 1, 2

Oropharyngeal Findings

• Glossitis (inflammation of the tongue) characterized by:
  • Atrophic glossitis with papillary atrophy 4, 5
  • Painful erythematous areas on the tongue 5
  • Burning sensation in the mouth (stomatodynia) 4, 5
  • Lingual paresthesia and itching 5
  • Dysgeusia (altered taste) 5

Hematologic Findings

• Pallor of skin, mucous membranes, and conjunctiva suggesting anemia 6
• Tachycardia and flow murmurs due to anemia 6
• Jaundice (in severe cases) due to ineffective erythropoiesis and hemolysis 6

General Findings

• Signs of fatigue and weakness 1
• In advanced cases, signs of dementia or delirium 1, 3

Clinical Pitfalls to Avoid

• Neurological symptoms may precede hematologic abnormalities, so absence of anemia does not rule out B12 deficiency 7, 2
• Oral manifestations often appear before systemic markers of deficiency become abnormal, making them crucial early diagnostic signs 4, 5
• Megaloblastic anemia can be masked by concurrent folic acid supplementation, so normal blood counts don't exclude B12 deficiency 2
• Patients taking medications such as metformin, proton pump inhibitors, H2 blockers, or colchicine may develop B12 deficiency despite normal dietary intake 1, 8

High-Risk Populations Requiring Closer Examination

• Elderly patients (>75 years) 8
• Patients with autoimmune conditions (thyroid disease, Sjögren syndrome, type 1 diabetes) 1, 2
• Patients with gastrointestinal disorders or history of gastrointestinal surgery 2, 8
• Vegans or strict vegetarians 1, 8
• Patients on long-term medication therapy with metformin, proton pump inhibitors, or H2 blockers 1, 8

Diagnostic Approach When Physical Findings Suggest B12 Deficiency

• Initial laboratory assessment should include complete blood count and serum vitamin B12 level 8
• For indeterminate results or when clinical suspicion remains high despite normal B12 levels, measure methylmalonic acid (MMA) and homocysteine levels 3, 2
• Consider measuring active B12 (holotranscobalamin) as it is more sensitive than total B12 3, 9