Optimal Result: 0.2 - 2.3 mg/dL.

Vitamin C is one of the water-soluble vitamins needed for health and survival. Its main functions include immunity, the synthesis of collagen and neurotransmitters, and protein metabolism. Vitamin C is one of the antioxidants used by the body to slow down aging and quench free radicals that may be involved in infections. The vitamin stimulates the synthesis of white blood cells, including phagocytes that engulf foreign bacteria. 

The body tissues that concentrate vitamin C are the white blood cells, eyes, and the adrenal glands. Studies show that vitamin C is very beneficial for cancer prevention and treatment, the healing of wounds, preventing eye disorders such as macular degeneration, healing from heart disease, and preventing the common cold.

Normal Ranges for Vitamin C in mg/dL or umol/L:

Adults: 0.6-2 mg/dL or > or equal to 50 umol/L (plasma)

Critical Range: <0.3 mg/dL or <11 umol/L (plasma)


  1. https://emedicine.medscape.com/article/2088649-overview
  2. http://lpi.oregonstate.edu/mic/vitamins/vitamin-C 
  3. http://www.lifeextension.com/Vitamins-Supplements/itemLC001479/Vitamin-C-Blood-Test#description 

What does it mean if your Vitamin C result is too low?

A vitamin C deficiency is called scurvy. Signs of a deficiency include the following:

- Easy bruising from weakened blood vessels

- Fatigue

- Wound healing that is prolonged

- Inflammation of the gums with bleeding during brushing

- Pain in the joints

Some specific causes of low vitamin C levels might be: 

- Failure to eat citrus fruits 

- Renal dialysis

- Malabsorption syndromes

- Pregnancy

- Hyperthyroidism

- Use of oral contraceptives or aspirin (Eight aspirin tablets a day has lowered vitamin C levels by 50% in studies.)

- Smoking habit or exposure to second-hand smoke

- Patients with iron overload (Iron is antagonistic to vitamin C)

- Type 1 diabetes

- Lead toxicity

- Infants that receive cow’s milk or evaporated milk without any additional source of vitamin C

What does it mean if your Vitamin C result is too high?

Vitamin C is not toxic and there is no known toxic level for it. The vitamin is given intravenously for various conditions without any side effects. However, supplement intake of vitamin C in amounts greater than 1-2 grams can cause some individuals to experience loose stools.

However, in those who have a glucose-6-phosphatase deficiency, blood cell fragility may occur when levels are too high. This may result in bruising or hemorrhaging. 

High Vitamin C might be associated with taking high doses of supplements.

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