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CPE-009 · Safety
B12-05: Neurologic or psychiatric features with unmeasured or low B12
Neurologic or psychiatric features with unmeasured or low B12. Evaluates peripheral neuropathy, balance problems, cognitive change or psychiatric symptoms.
Condition
- peripheral neuropathy, balance problems, cognitive change or psychiatric symptoms
- vitamin B12 not measured, OR below 300 pg/mL, OR nitrous oxide exposure (a normal serum level does not exclude functional deficiency)
What it reports
- Neurologic involvement raises the urgency of finding vitamin B12 deficiency, and can occur without anemia
Recommended next steps (for physician review)
- Measure B12 (with MMA) promptly
- BSH advises that neurologic involvement is a reason not to delay treatment while awaiting results
Diagnostic boundary
- Neuropathy has many causes; this rule asks that B12 not be overlooked.
Evidence
- EV-BSH-2014Devalia V, Hamilton MS, Molloy AM; British Committee for Standards in Haematology. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. Br J Haematol. 2014;166(4):496-513.Supports: Diagnostic approach with serum B12, MMA and homocysteine Neurologic involvement means treatment should not wait for confirmation Folic acid alone must not be given while B12 deficiency is unexcluded
- EV-STABLER-2013Stabler SP. Vitamin B12 deficiency. N Engl J Med. 2013;368(2):149-160.Supports: Clinical presentations, subacute combined degeneration, nitrous oxide and drug causes
Cases where this rule fires
Open a case to see this rule fire with real inputs, then change the values until it stops.
B12-FX-05
Neuropathy, B12 220 and metformin for five years
Neurologic features with a borderline level.
B12-FX-06
Posterior-column signs and spasticity
A pattern compatible with subacute combined degeneration.
B12-FX-13
Nitrous oxide exposure with neuropathy and a B12 of 310
A normal-looking serum level.
B12-FX-24
Numb feet and unsteady, B12 never measured
Neurologic features without a level.
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