Vitamin C (ascorbic acid) functions in many metabolic processes, especially in those related to collagen formation and the stress response. In addition, vitamin C helps to maintain capillary strength, facilitates the release of iron from ferritin for hemoglobin formation and red blood cell maturation, and may maintain the integrity of the amniotic sac.

Elevated vitamin C levels are associated with excessive intake of the vitamin within 24 hours of the test. Decreased intake produces scurvy with low vitamin C levels.

• Excessive intake of vitamin C within 24 hours of the test will produce elevated levels.
• Failure to follow dietary restrictions before the test may alter results.

• Evaluation of the effects of major stressors (e.g., pregnancy, major surgery, burns, infections, malignancies) on vitamin C levels
• Evaluation of the effects of malabsorption syndromes on vitamin C levels
• Evaluation of the effectiveness of therapy with vitamin C in treating deficiency states

Nursing Care Before the Procedure

General client preparation is the same as that for any study involving collection of a peripheral blood sample (see Appendix I).

• For this test, the client should fast from food for 8 hours beforehand.
• Vitamin C preparations also should be withheld for 24 hours before the study.

A venipuncture is performed and the sample collected in a black-topped tube. The sample is handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any test involving the collection of a peripheral blood sample.

• Resume usual diet.
• Vitamin C preparations may be resumed pending test results.
• Decreased level: Note and report symptoms of deficiency or decreased level such as bleeding and poor wound healing. Instruct client to eat foods high in vitamin C to correct deficiency. Administer oral vitamin C supplement in ordered dosage.
• Increased level: Note and report symptoms of excesses or increased level. Discontinue the oral intake to prevent overdose; high doses taken as a preventive treatment can cause renal calculi.