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Ascorbic Acid Tolerance Blood and Urine Test

Last updated Jan. 26, 2016

What are other Names for this Test? (Equivalent Terms)

  • Ascorbate Tolerance Blood and Urine Test
  • Vitamin C Tolerance Blood and Urine Test

What is the Ascorbic Acid Tolerance Blood and Urine Test? (Background Information)

  • Vitamin C, or ascorbic acid, is needed for growth, development, and maintenance of bodily tissues. It is especially important in tissue repair and fighting infections
  • Vitamin C is essential for the functioning of key enzymes in the body. This is because it is a cofactor, meaning that it plays vital roles in the chemistry of enzymes
  • Vitamin C is water-soluble, and hence, excess ascorbic acid is excreted in urine, as opposed to being stored in the fat tissue
  • Fresh fruits, such as lemons, kiwi, and oranges, are rich in vitamin C. Vitamin C is sensitive to heat. Consequently, cooking foods destroys much of their vitamin C content
  • The Ascorbic Acid Tolerance Blood and Urine Test help determine the levels of vitamin C (ascorbic acid) in blood and urine. It is used to diagnose vitamin C deficiency

What are the Clinical Indications for performing the Ascorbic Acid Tolerance Blood and Urine Test?

Following are the clinical indications for performing the Ascorbic Acid Tolerance Blood and Urine Test:

  • Fever
  • Enlarge lymph nodes
  • Fatigue
  • Pain in the gums
  • Severe burns

How is the Specimen Collected for the Ascorbic Acid Tolerance Blood Test?

Following is the specimen collection process for Ascorbic Acid Tolerance Blood and Urine Test:

Sample required: Blood and urine

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Process of obtaining a urine sample in adults: Urination into a sterile container over a 24-hour period.

Preparation required:

  • No special preparation is needed prior to the blood test
  • Drinking 6-8 glasses of water or other fluids is advised prior to the urine test
  • However, consuming ascorbate-rich foods, such as lemons and oranges, before the test can influence its outcome

What is the Significance of the Ascorbic Acid Tolerance Blood Test Result?

The significance of the Ascorbic Acid Tolerance Blood and Urine Test result is explained.

  • A high test value may indicate excess vitamin C administration
  • A low test value may indicate:
    • Infection
    • Severe burns
    • Cancer
    • Scurvy

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Certain factors interfere with the Ascorbic Acid Blood and Urine Test. These include consumption of ascorbate-rich foods, such as lemons and oranges, prior to performing the test

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

What are some Useful Resources for Additional Information?

The following DoveMed website link is a useful resource for additional information:


Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Kee, J. L. (2010). Laboratory and diagnostic tests with nursing implications (8th ed.). Upper Saddle River, NJ: Pearson.

Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.

Schnell, Z. B., Van, L. A., & Kranpitz, T. R. (2003). Davis's Comprehensive handbook of laboratory and diagnostic tests: With nursing implications. Philadelphia: F.A. Davis.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Jan. 26, 2016
Last updated: Jan. 26, 2016