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Epic Test Code LAB671 Ascorbic Acid (Vitamin C), Plasma

Additional Codes

MML:VITC

Useful For

Identifying vitamin C deficiency

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Portions of this test are covered by patents held by Quest Diagnostics

Reporting Name

Ascorbic Acid, P

Specimen Type

Plasma Heparin


Shipping Instructions


Ship specimen frozen on dry ice in amber vial to protect from light.



Specimen Required


Patient Preparation: Fasting overnight (12-14 hours) (infants-collect prior to next feeding). Water can be taken as needed.

Supplies: Amber Frosted Tube, 5 mL (T915)

Collection Container/Tube:

Preferred: Green top (sodium or lithium heparin)

Submission Container/Tube: Amber vial

Specimen Volume: 1 mL

Collection Instructions:

1. Immediately place specimen on wet ice and process within 4 hours of collection.

2. Centrifuge at 4° C, aliquot plasma into amber vial to protect from light.

3. Freeze plasma immediately, ideally at or below -60° C, protected from light.


Bassett Healthcare Network Clinical Laboratories Note:

Blood Tube Draw Volume
Min 50% draw volume  

  • 50% of the tube fill volume is required for proper blood to additive ratio.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Heparin Frozen 14 days LIGHT PROTECTED

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Clinical Information

Vitamin C, also known as L-ascorbic acid or simply ascorbic acid, is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement. Humans, unlike most animals, are unable to synthesize vitamin C endogenously, so it is an essential dietary component. Vitamin C is required for the enzymatic amidation of neuropeptides, production of adrenal cortical steroid hormones, promotion of the conversion of tropocollagen to collagen, and metabolism of tyrosine and folate. It also plays a role in lipid and vitamin metabolism and is a powerful reducing agent or antioxidant. Specific actions include activation of detoxifying enzymes in the liver; antioxidation, interception and destruction of free radicals; preservation and restoration of the antioxidant potential of vitamin E; and blockage of the formation of carcinogenic nitrosamines. In addition, vitamin C appears to function in a variety of other metabolic processes in which its role has not been well characterized.

 

Prolonged deficiency of vitamin C leads to the development of scurvy, a disease characterized by an inability to form adequate intercellular substance in connective tissues. This results in the formation of swollen, ulcerative lesions in the gums, mouth, and other tissues that are structurally weakened. Early symptoms may include weakness, easy fatigue and listlessness, as well as shortness of breath, and aching joints, bones, and muscles.

 

The need for vitamin C can be increased by the use of aspirin, oral contraceptives, tetracycline, and a variety of other medications. Psychological stress and advancing age also tend to increase the need for vitamin C. Among older adults, lack of fresh fruit and vegetables often adds vitamin C depletion to the inherently increased need, with development of near-scurvy status.

Reference Values

0.4-2.0 mg/dL

Interpretation

Values below 0.2 mg/dL indicate significant deficiency.

 

Values greater than or equal to 0.2 mg/dL and less than 0.4 mg/dL are consistent with a moderate risk of deficiency due to inadequate tissue stores.

 

Values of 0.4 to 2.0 mg/dL indicate adequate supply.

 

The actual level at which vitamin C is excessive has not been defined. Values above 3.0 mg/dL are suggestive of excess intake. Whether vitamin C in excess is indeed toxic continues to be uncertain. However, limited observations suggest that this condition may induce uricosuria and, in individuals with glucose-6-phosphate dehydrogenase deficiency, may induce increased red blood cell fragility.

Cautions

Testing of nonfasting specimens or the use of vitamin supplementation can result in elevated plasma vitamin concentrations. Reference values were established in patients who were fasting.

 

After consuming vitamin C, plasma values rapidly rise within 1 to 2 hours and reach peak concentration within 3 to 6 hours after ingestion.

Day(s) Performed

Monday through Friday

Report Available

3 to 5 days

Specimen Retention Time

2 weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82180

NY State Approved

Yes