What is the best course of treatment for a patient with vitamin B12 deficiency, type 2 diabetes mellitus, and dyslipidemia, presenting with tiredness, neurological symptoms, and a family history of pernicious anemia?

Treatment of Vitamin B12 Deficiency with Neurological Symptoms in a Patient with Type 2 Diabetes and Dyslipidemia

Immediate B12 Treatment Protocol

This patient requires intensive hydroxocobalamin 1 mg intramuscularly on alternate days until no further neurological improvement is observed, then transition to maintenance dosing of 1 mg every 2 months for life. 1

The presence of neurological symptoms (tingling in feet, difficulty concentrating, brain fog, balance issues requiring a walker) mandates the more aggressive alternate-day dosing regimen rather than the standard weekly protocol 1. The chronic diarrhea that resolved with B12 supplementation, combined with the family history of pernicious anemia, strongly suggests malabsorption requiring lifelong parenteral therapy 1.

Key Treatment Considerations:

• Never administer folic acid before treating B12 deficiency, as this may mask the deficiency and precipitate subacute combined degeneration of the spinal cord 1, 2
• The patient's folate level of 18.6 is adequate, so no folate supplementation is needed 1
• Intramuscular administration is mandatory given the malabsorption history (chronic diarrhea) 1
• Neurological symptoms may take 6-12 months to improve and some may be irreversible if treatment is delayed 3

Diagnostic Workup:

• Test for intrinsic factor antibodies immediately to confirm pernicious anemia, which would necessitate lifelong treatment 3
• Consider methylmalonic acid (MMA) testing if B12 levels remain indeterminate on follow-up, as it's a more sensitive marker of functional B12 status 3
• The B12 level of 141 is clearly deficient by UK standards (<150 pmol/L or <203 pg/mL) 3

Metformin's Role in B12 Deficiency

Metformin is a significant contributor to this patient's B12 deficiency and should be continued with close monitoring rather than discontinued. 3, 4

• Metformin use for more than 4 months increases B12 deficiency risk, particularly when combined with chronic diarrhea (a known metformin side effect that worsens malabsorption) 3, 4
• The patient has been on metformin for 4+ years, making this a major contributing factor 4
• Despite metformin's role, it should be continued for diabetes management while ensuring adequate B12 replacement 4
• Monitor B12 levels every 3 months until stabilization, then annually 2

Diabetes Management

Continue current diabetic medications (Jardiance, Metformin, Lantus, Novorapid) without changes at this time. The suboptimal glycemic control should be addressed after B12 deficiency treatment is established, as B12 deficiency itself can worsen diabetic control and neurological symptoms 4.

• The patient is already under specialist diabetic nurse care (Nicola Holmes) [@patient history@]
• Coordinate B12 treatment with the diabetes team to optimize overall management 4
• Dietary adherence counseling should continue as planned [@patient history@]

Dyslipidemia Management

Increase rosuvastatin from 10mg to 20mg daily (take 2 tablets instead of one) immediately. [@patient history@]

• Triglycerides of 5.3 (increased from 2.4) and HDL of 0.81 (decreased) represent significant cardiovascular risk [@patient history@]
• The patient has heart failure and diabetes, making aggressive lipid management essential [@patient history@]
• Continue dietary modifications alongside statin intensification [@patient history@]
• Recheck lipid panel in 6-12 weeks after statin dose increase

Monitoring Protocol

Short-term (First 3 months):

• Assess neurological symptoms at each B12 injection visit 1
• Monitor for improvement in tingling, balance, and cognitive symptoms 3
• Check serum potassium in the first 48 hours of treatment, as B12 replacement can cause hypokalemia 5
• Recheck B12 levels and MMA at 3 months 3, 2

Long-term:

• Once neurological improvement plateaus, transition to maintenance hydroxocobalamin 1 mg IM every 2 months for life 1
• Annual B12 level monitoring after stabilization 2
• Continue cardiology follow-up (P2 priority appointment expected within 4 weeks) [@patient history@]

Critical Pitfalls to Avoid

• Do not use oral B12 supplementation in this patient despite evidence that oral therapy can be effective in some cases 6, 7. The chronic diarrhea, likely malabsorption, and neurological involvement mandate parenteral therapy 1
• Do not reduce injection frequency prematurely before neurological symptoms plateau 1
• Do not discontinue B12 therapy even if levels normalize, as this patient will require lifelong treatment given the likely pernicious anemia and metformin use 1, 3
• Do not delay treatment while awaiting intrinsic factor antibody results, as neurological damage can become irreversible 3, 5