How should I work up the causes of vitamin C deficiency in a patient presenting with petechiae, gingival bleeding, perifollicular hemorrhages, cork‑screw hair, fatigue, arthralgia, and poor wound healing?

Workup of Vitamin C Deficiency

When clinical features of scurvy are present—petechiae, gingival bleeding, perifollicular hemorrhages, corkscrew hairs, fatigue, arthralgia, and poor wound healing—initiate treatment immediately without waiting for laboratory confirmation. 1

Clinical Diagnosis Takes Priority

• Diagnosis is primarily clinical based on characteristic mucocutaneous findings, which include petechiae, ecchymoses, bleeding gums, gingival swelling, perifollicular purpura, corkscrew hairs, and follicular hyperkeratosis. 1, 2
• The constellation of symptoms you describe—petechiae, gingival bleeding, perifollicular hemorrhages, corkscrew hair, fatigue, arthralgia, and poor wound healing—is diagnostic of scurvy and warrants immediate treatment. 3, 1, 4
• Do not delay treatment while awaiting laboratory results if the clinical presentation is consistent with vitamin C deficiency. 1

Laboratory Testing Strategy

When to Order Testing

• Plasma vitamin C measurement is the preferred laboratory test when confirmation is needed for suspected scurvy or chronic low intake. 1
• Testing should only be ordered in patients with suspected scurvy or documented chronic inadequate intake, not routinely. 1, 5

Critical Testing Limitations

• Plasma vitamin C levels are unreliable during any inflammatory state—levels decline when C-reactive protein (CRP) exceeds 10 mg/L, and normal values are typically undetectable when CRP exceeds 40 mg/L. 1, 5
• Never measure vitamin C levels during acute illness, critical illness, or active inflammation, as results will be falsely low and misleading. 1, 5
• Vitamin C samples require special handling for accurate measurement. 5

Identifying the Underlying Cause

Dietary History Assessment

• Document specific vitamin C intake by asking about consumption of citrus fruits (oranges, lemons), tomatoes, potatoes, cabbage, strawberries, cantaloupe, and papaya. 3, 6
• One medium-sized orange provides approximately 75-90 mg of vitamin C, meeting the daily requirement for healthy adults. 1
• Determine if intake has been below 40-45 mg/day, the threshold below which scurvy develops over 8-12 weeks. 3, 5

High-Risk Populations to Evaluate

Screen for these specific risk factors that predispose to vitamin C deficiency:

• Malnutrition and food insecurity: inadequate access to fresh fruits and vegetables 7, 8, 2
• Alcohol use disorder: impairs dietary intake and absorption 8, 2
• Psychiatric disorders and restrictive eating habits: including severe mental illness, autism spectrum disorder, or self-imposed dietary restrictions 7, 8, 2
• Smoking: increases oxidative stress and vitamin C turnover, requiring an additional 35 mg/day above baseline 5
• Chronic dialysis: removes water-soluble vitamins including vitamin C 3, 1
• Post-bariatric surgery: malabsorption of water-soluble vitamins 1, 5
• Critical illness or major surgery: dramatically increases vitamin C requirements to 2-3 g/day 1, 5
• Chronic oxidative stress conditions: diabetes, heart failure, chronic obstructive pulmonary disease 1, 5

Malabsorption Workup

If the patient fails to respond to adequate oral supplementation or has no clear dietary cause, investigate gastrointestinal malabsorption. 7, 8

• Check for inflammatory bowel disease (Crohn's disease, ulcerative colitis), which impairs absorption of water-soluble vitamins. 8
• Evaluate for celiac disease if other nutritional deficiencies are present. 7
• Screen for other fat-soluble and water-soluble vitamin deficiencies (vitamins A, D, E, K, B12, folate, thiamin) to identify a broader malabsorptive syndrome. 7
• Consider small bowel bacterial overgrowth, chronic pancreatitis, or short bowel syndrome in appropriate clinical contexts. 8

Medication Review

• Review medications that may interfere with vitamin C absorption or increase requirements, though this is rarely a primary cause. 8

Confirming Response to Treatment

• Clinical improvement should occur within days to weeks of initiating vitamin C supplementation—gingival bleeding resolves first, followed by petechiae and ecchymoses, then fatigue and arthralgias. 1, 2
• If symptoms persist despite 300-500 mg/day oral supplementation for 2-4 weeks, suspect malabsorption and consider switching to parenteral (intramuscular, intravenous, or subcutaneous) administration. 1, 8
• One case report documented a patient requiring long-term home intravenous vitamin C due to severe Crohn's disease preventing adequate oral absorption despite 2000 mg/day oral supplementation. 8

Common Pitfalls to Avoid

• Do not measure vitamin C levels in patients with elevated inflammatory markers (CRP >10 mg/L), as results will be falsely low and may lead to unnecessary escalation of therapy. 1, 5
• Do not assume adequate dietary intake based on patient report alone—many patients overestimate their fruit and vegetable consumption. 2
• Do not overlook scurvy in well-nourished appearing patients—malabsorption can cause deficiency even with adequate intake. 7
• Do not confuse scurvy with hematologic disorders (thrombocytopenia, coagulopathy) or vasculitis—the perifollicular distribution and corkscrew hairs are pathognomonic for vitamin C deficiency. 7, 2, 4