What is the best course of treatment for a patient with vitamin D deficiency, elevated ferritin, and symptoms of fatigue and hypotension?

Treatment Approach for Vitamin D Deficiency with Fatigue and Hypotension

Initiate vitamin D supplementation with cholecalciferol 50,000 IU weekly for 8 weeks to address the vitamin D deficiency (level 28 ng/mL), which is the most likely contributor to the patient's fatigue. 1, 2

Iron Status Assessment

Your patient's iron studies do not indicate iron deficiency requiring treatment:

• Ferritin 288 ng/mL is well above deficiency thresholds (deficiency defined as <45 ng/mL generally, or <100 ng/mL in inflammatory states) 3
• Iron 47 mcg/dL is within normal range (normal: 50-175 mcg/dL, though this is borderline low) 3
• No anemia is present based on the information provided 3

Do not supplement iron at this time. The ferritin level of 288 ng/mL indicates adequate iron stores, and supplementation above this level is not recommended and potentially harmful 3. Iron supplementation should only occur when ferritin is <100 ng/mL (or <100-300 ng/mL with transferrin saturation <20% in specific conditions like heart failure) 3.

Vitamin D Deficiency Management

The vitamin D level of 28 ng/mL meets criteria for deficiency (defined as <30 ng/mL) 3, 2:

Treatment protocol:

• Ergocalciferol (vitamin D2) 50,000 IU orally once weekly for 8 weeks 2
• Alternatively, cholecalciferol (vitamin D3) 50,000 IU weekly can be used 1
• After normalization, maintain with cholecalciferol 800-1,000 IU daily 2, 4
• Recheck 25-hydroxyvitamin D level in 3 months to ensure adequate response 3

The goal is to achieve a serum 25-hydroxyvitamin D level >30 ng/mL (75 nmol/L) to maximize beneficial effects and resolve symptoms 4.

Fatigue Etiology

Vitamin D deficiency is the most plausible explanation for this patient's fatigue:

• Vitamin D deficiency commonly presents with fatigue, muscle weakness, and nonspecific musculoskeletal complaints 2, 5
• Case reports demonstrate complete resolution of daytime fatigue with vitamin D supplementation when levels normalize 5
• The mechanism may involve effects on inflammatory cascades including tumor necrosis factor-alpha and prostaglandin D2 5

Hypotension Considerations

The slight low blood pressure is not related to the vitamin D deficiency or iron status based on available evidence. Consider:

• Evaluate for other causes: dehydration, medications, autonomic dysfunction, or cardiac issues
• Blood pressure management is not indicated unless systolic ≥130 mmHg or diastolic ≥80 mmHg in patients with chronic kidney disease 3
• The hypotension may improve secondarily as fatigue resolves and activity levels increase

Monitoring Plan

Follow-up schedule:

• Reassess symptoms in 3 months after vitamin D repletion 5
• Recheck 25-hydroxyvitamin D level at 3 months to confirm normalization 3
• Do not recheck iron studies unless anemia develops or clinical picture changes 3
• If fatigue persists despite normalized vitamin D levels, pursue comprehensive workup including thyroid function, complete blood count, and metabolic panel 2

Critical Pitfalls to Avoid

• Do not supplement iron with ferritin 288 ng/mL - this is unnecessary and potentially harmful 3
• Do not use vitamin D2 or D3 doses lower than 50,000 IU weekly for deficiency correction - standard daily doses take many weeks to normalize levels 3
• Do not attribute all symptoms to a single cause - if fatigue persists after vitamin D normalization, investigate other etiologies 2
• Ferritin is an acute phase reactant - the level of 288 ng/mL could be falsely elevated if inflammation is present, but without anemia, iron supplementation is still not indicated 3