nutritional disorders
Vitamin C Deficiency
Diagnosis of Vitamin C Deficiency
Usually clinical (based on skin or gingival findings and risk factors) Diagnosis of vitamin C deficiency is usually made clinically in a patient who has skin or gingival signs and is at risk of vitamin C deficiency. Laboratory confirmation may be available. Complete blood count is done, often detecting anemia. Bleeding, coagulation, and prothrombin times are normal. Skeletal x-rays can help diagnose childhood (but not adult) scurvy. Changes are most evident at the ends of long bones, particularly at the knee. Early changes resemble atrophy. Loss of trabeculae results in a ground-glass appearance. The cortex thins. A line of calcified, irregular cartilage (white line of Fraenkel) may be visible at the metaphysis. A zone of rarefaction or a linear fracture proximal and parallel to the white line may be visible as only a triangular defect at the bone’s lateral margin but is specific. The epiphysis may be compressed. Healing subperiosteal hemorrhages may elevate and calcify the periosteum. Laboratory diagnosis, which requires measuring bloodascorbic acid, is sometimes done at academic centers. Levels of<0.6 mg/dL (<34 mcmol/L) are considered marginal; levels of<0.2 mg/dL (<11 mcmol/L) indicate vitamin C deficiency. Measurement ofascorbic acidlevels in the white blood cell-platelet layer of centrifuged blood is not widely available or standardized. In adults, scurvy must be differentiated from arthritis, hemorrhagic disorders, gingivitis, and protein-energy undernutrition. Hyperkeratotic hair follicles with surrounding hyperemia or hemorrhage are almost pathognomonic. Bleeding gums, conjunctival hemorrhages, most petechiae, and ecchymoses are nonspecific. 