In a 17-year-old female with mild anemia (hemoglobin 11.8 g/dL, hematocrit 35.2%) and otherwise normal studies, should I order a vitamin C level?

Should You Order a Vitamin C Level in This Patient?

No, you should not order a vitamin C level in this 17-year-old female with mild anemia—instead, prioritize iron studies (serum ferritin, transferrin saturation, and TIBC) to evaluate for iron deficiency, which is the most common cause of anemia in menstruating adolescent females. 1, 2

Rationale for Not Testing Vitamin C

Vitamin C Deficiency is Extremely Rare in This Population

• Scurvy (clinical vitamin C deficiency) occurs almost exclusively in severely malnourished individuals, alcoholics, or those with extremely restricted diets, and would present with characteristic features such as perifollicular hemorrhages, corkscrew hairs, gingival bleeding, and petechiae—not isolated mild anemia 3
• The patient's hemoglobin of 11.8 g/dL represents only mild anemia (WHO defines anemia as <12 g/dL in non-pregnant women), making vitamin C deficiency as the primary cause highly unlikely 2

Vitamin C Testing Has Significant Practical Limitations

• Plasma vitamin C measurement requires extensive pre-analytical precautions including immediate centrifugation at 4°C, ultra-low temperature storage (-70 to -80°C), and protection from light throughout the entire workflow, making it impractical for routine clinical use 1
• Vitamin C levels decline rapidly with any degree of inflammation (CRP >10 mg/L), and normal values are not detected when CRP >40 mg/L, severely limiting interpretation 1

What You Should Order Instead

First-Line Iron Studies

• Serum ferritin <30 μg/L confirms iron deficiency in the absence of inflammation and is the single most useful marker 1, 2
• Transferrin saturation <15-20% supports iron deficiency and is less affected by inflammatory states than ferritin 1, 2
• Total iron-binding capacity (TIBC) should be included as part of the complete iron panel 1

Additional Essential Tests

• Reticulocyte count to evaluate bone marrow response to anemia—a low or inappropriately normal count indicates inadequate erythropoiesis 1, 2
• C-reactive protein (CRP) to interpret ferritin values, since ferritin rises as an acute-phase reactant during inflammation 2

Consider in Specific Contexts

• Vitamin B12 and folate levels if the MCV were elevated (macrocytic anemia) or if there were neurologic symptoms, but these are not indicated for normocytic/microcytic anemia in a young woman 2
• Celiac serology (tissue transglutaminase antibody) if iron deficiency is confirmed, as malabsorption can cause refractory iron deficiency 1

Clinical Context: Why Iron Deficiency is Most Likely

Epidemiologic Considerations

• Menstrual blood loss is the most common cause of iron deficiency anemia in premenopausal women 1
• Iron deficiency occurs in a substantial proportion of adolescent females due to increased iron requirements during growth combined with menstrual losses 1

Hematologic Pattern

• The hematocrit of 35.2% (normal range typically 36-44% for women) combined with hemoglobin 11.8 g/dL suggests early iron deficiency even before frank microcytosis develops 2
• If MCV and MCH are low-normal or reduced with elevated RDW, this pattern is highly suggestive of iron-deficient erythropoiesis 2

Important Caveats

When Vitamin C Might Be Relevant (But Still Not Tested)

• If iron deficiency is confirmed and the patient is starting oral iron supplementation, vitamin C enhances non-heme iron absorption when consumed with iron-containing meals 1, 4
• However, supplemental vitamin C should be avoided in patients with hemochromatosis or iron overload, as it can mobilize iron stores and potentially worsen organ damage 1
• The evidence for routine vitamin C supplementation with iron therapy is mixed—meta-analysis shows no statistically significant benefit in hemoglobin or ferritin levels when vitamin C is added to iron supplementation 5

Mixed Deficiency Pitfall

• In elderly patients or those with inflammatory bowel disease, simultaneous iron and vitamin B12 deficiencies can neutralize the MCV (making it appear normal) while elevating RDW—this requires assessment of both iron and B12 status 2
• This is less likely in a 17-year-old without gastrointestinal symptoms, but keep it in mind if iron studies are normal

Practical Algorithm

1. Order iron studies immediately: ferritin, transferrin saturation, TIBC, and CRP 1, 2
2. Add reticulocyte count to assess marrow response 1, 2
3. If ferritin <30 μg/L or TSAT <20%: diagnose iron deficiency and initiate oral iron supplementation (ferrous sulfate 325 mg once to three times daily) 2
4. If iron studies are normal: consider hemoglobinopathy screening (hemoglobin electrophoresis) if appropriate ethnic background, or evaluate for chronic disease 2
5. Reserve vitamin C testing only for patients with clinical signs of scurvy (gingival bleeding, perifollicular hemorrhages, poor wound healing) in the context of severe malnutrition 3