In a chronic smoker recently treated for tuberculosis who completed a course of antibiotics and now has a dry, bright‑red tongue with small painless papular lesions for three weeks, could this presentation be due to a vitamin deficiency?

Dry, Red Tongue with Papular Lesions Following Antibiotic Use in TB Patient

Most Likely Diagnosis: Riboflavin (Vitamin B2) Deficiency

This presentation is most consistent with riboflavin deficiency, which manifests as glossitis (red, inflamed tongue), angular stomatitis, and oral-buccal lesions—all of which can be triggered or worsened by antibiotic therapy and the hypermetabolic state of tuberculosis. 1

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Clinical Reasoning

Why Riboflavin Deficiency Fits This Case

• Glossitis (red, inflamed tongue) is a classic manifestation of riboflavin deficiency, often accompanied by angular stomatitis and cheilosis 1
• Tuberculosis patients are at high risk for multiple vitamin deficiencies, including riboflavin, due to increased metabolic demands, poor nutritional intake, and the inflammatory response 2
• Antibiotic therapy can precipitate or worsen riboflavin deficiency by disrupting the gut microflora that normally produces riboflavin in the large intestine 1
• Chronic smoking further depletes riboflavin stores and increases oxidative stress, compounding the deficiency 1
• The 3-week timeline aligns with depletion of riboflavin stores, as the body does not store riboflavin in ample amounts and requires constant dietary supply 1

Supporting Evidence from TB Context

• Patients with tuberculosis commonly have multiple concurrent vitamin deficiencies, with one study showing 22.4% of TB patients had multiple vitamin deficiencies versus 0% of controls 2
• The inflammatory response in TB significantly reduces plasma riboflavin levels by 30-40%, making deficiency more likely even with adequate intake 1
• Anti-tuberculosis drug therapy is associated with worsened baseline vitamin deficiency and increased adverse effects, with 38.5% of TB patients experiencing adverse responses 3

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Differential Considerations

Other B Vitamin Deficiencies to Consider

• Vitamin B12 deficiency can cause glossitis (inflammation of the tongue) and is common in TB patients, with elevated methylmalonic acid levels found in 134.9 nmol/L versus 110.8 nmol/L in controls 4, 2
• However, B12 deficiency typically presents with neurological symptoms (paresthesias, numbness, gait ataxia) and macrocytic anemia, which are not mentioned in this case 4, 5
• Riboflavin deficiency is frequently associated with pyridoxine, folate, and niacin deficiencies, so concurrent deficiencies should be considered 1

Why Not Other Vitamin Deficiencies

• Vitamin A deficiency is common in TB patients (1.4 vs. 2.0 μmol/L in controls), but primarily causes ocular symptoms and skin changes rather than isolated glossitis 2
• Vitamin D deficiency is highly prevalent in TB (10.6 vs. 19.3 ng/mL in controls), but does not cause oral lesions 2
• Vitamin E deficiency occurs in TB patients (22.8 vs. 30.6 μmol/L in controls), but manifests as sensory neuropathy, not oral symptoms 2

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Diagnostic Approach

Immediate Assessment

• Measure plasma riboflavin levels, though note that plasma levels are significantly decreased (30-40%) in the context of inflammation, making interpretation challenging 1
• Erythrocyte glutathione reductase activity test is more reliable in inflammatory conditions and better reflects tissue saturation and long-term status 1
• Check complete blood count to assess for normochromic, normocytic anemia, which can occur with riboflavin deficiency 1

Concurrent Vitamin Screening

• Screen for B12 deficiency with serum B12 and methylmalonic acid, as TB patients have elevated MMA levels (134.9 vs. 110.8 nmol/L) 2
• Measure vitamins A, D, and E, as multiple vitamin deficiencies are common in TB patients (22.4% prevalence) 2
• Check iron studies and folate, as riboflavin deficiency interferes with iron handling and often coexists with other B vitamin deficiencies 1

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Treatment Recommendations

Riboflavin Supplementation

• Initiate riboflavin 3.6-5 mg daily as recommended for parenteral nutrition, which is appropriate for patients with malabsorption or increased requirements 1
• Higher doses (10 mg/day) may be needed in elderly patients or those with severe deficiency, as demonstrated in randomized controlled trials 1
• Continue treatment until clinical symptoms resolve and plasma levels normalize, typically requiring several weeks 1

Addressing Underlying Risk Factors

• Optimize nutritional intake with foods rich in riboflavin: enriched grains, cereals, meats, dairy products, fatty fish, eggs, and dark-green vegetables 1
• Consider probiotic supplementation to restore gut microflora that produces riboflavin, which may have been disrupted by antibiotic therapy 1
• Smoking cessation counseling is essential, as chronic smoking depletes riboflavin and other vitamins 1

Comprehensive Micronutrient Support

• Supplementation with multiple micronutrients (including zinc) rather than single vitamins may be more beneficial in TB patients, though specific clinical trial data is lacking 6
• Monitor for other vitamin deficiencies given the high prevalence of concurrent deficiencies in TB patients 2
• Reassess vitamin status after 3-6 months of treatment to ensure normalization 1

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Critical Pitfalls to Avoid

• Do not assume normal vitamin levels rule out deficiency in TB patients, as the inflammatory response significantly alters plasma concentrations of multiple vitamins 1, 2
• Do not overlook the impact of anti-TB drugs on vitamin metabolism, as first-line therapy can worsen baseline vitamin deficiency and alter vitamin D-dependent immune responses 3, 7
• Do not treat with folic acid before excluding B12 deficiency, as this may mask anemia while allowing irreversible neurological damage to progress 4
• Do not rely solely on dietary modification in patients with active TB and antibiotic therapy, as increased metabolic demands and malabsorption require supplementation 1, 2

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Follow-Up and Monitoring

• Clinical improvement should be evident within 1-2 weeks of riboflavin supplementation, with resolution of glossitis and oral lesions 1
• Recheck riboflavin levels after 3-6 months to confirm normalization and adjust dosing as needed 1
• Continue monitoring throughout TB treatment, as anti-tuberculosis drugs can perpetuate vitamin deficiencies 3, 7
• Screen annually for vitamin deficiencies in patients with chronic conditions or ongoing risk factors 1