Vitamin C (Ascorbic acid)

 Vitamin C (Ascorbic acid)

Sample

1. Serum or plasma can be used.
2. The whole blood for vitamin C is stable for 3 hours when refrigerated.
3. Deproteinized the serum or plasma with metaphosphoric acid (5 g/dL) or trichloroacetic acid (10 g/dL).

Precautions

• Avoid hemolysis.

Pathophysiology

1. This is a white crystalline solid which is easily soluble in water and easily absorbed from the stomach and intestine.
   1. This is strong reducing compounds and the source is dietary ingestion.
   2. Body stores can last for months.
2. Vit. C has a very important function in our body.

Vitamin C Functions

3. Vitamin C serves as a reducing agent in several hydroxylation reactions in the body.
4. This exists in two forms:
   1. L-ascorbic acid.
   2. Dehydroascorbic acid (Ascarbone).
      1. This form is more labile.
5. Absorption is mainly from the stomach.
   1. This has passive entry into the WBCs and RBCs.
   2. Active entry is into glandular tissue like the pituitary gland, adrenal cortex, corpus luteum, and thymus. While concentration in the retina is 20 to 30 times more than tissue.
6. Source of vitamin C:
   1. The best source of Vitamin C is :
      1. citrus fruits.
      2. Berries.
      3. Melons.
      4. Green pepper.
      5. Tomatoes.
      6. Raw cabbage.
      7. Leafy green vegetables.
      8. Potatoes.
   2. Heat can lead to the loss of vitamin C.
7. Vitamin C deficiency leads to Scurvy which will show clinically:
   1. Hemorrhagic disorder.
   2. There are swollen and bleeding gums.
   3. There is impaired healing.
   4. There is anemia.
8. Vitamin C is excreted in the urine. Its excretion is increased by:
   1. Aspirin.
   2. Aminopyrine.
   3. Barbiturates.
   4. Paraldehyde.
   5. Hydantoin.
9. Vitamin C absorption:

Vitamin C Absorption

Normal

Source 1

• Vitamin C = 0.4 to 1.5 mg/dL
• Defeciency level = <0.2 mg/dL

Other soureces

1. Daily requiremtns of vitamin C:
   1.  Infants
      1. 0 to 6 months =  40 mg/day
      2. 7 to 12 months = 50 mg/day
   2. Children
      1. 1 to  3 years =  15 mg/day
      2. 4 to 8 years = 25 mg/day
      3. 9 to 13 years =  45 mg/day
   3. Adolescents
      1. Girls 14 to 18 years = 65 mg/day
      2. Pregnant teens =  80 mg/day
      3. Breastfeeding teens =  115 mg/day
      4. Boys 14 to 18 years = 75 mg/day
   4. Adults
      1. Men age 19 and older =  90 mg/day
      2. Women age 19 years and older: = 75 mg/day
      3. Pregnant women =  85 mg/day
      4. Breastfeeding women = 120 mg/day
2. Vitamin C normal range = 0.2 to 2.0 mg / 100 ml.
   1. Deficiency when level is < 0.2 mg/dL.
3. Vitamin C level in Leucocytes = 20 to 53 µg/10^8 leucocytes.
   1. Deficient value when is  <10 µg / 10^8 leucocytes.
4. Urinary excretion of vitamin C = 8 to 27 mg/day.

Deficiency of Vit.C, Clinical effects of decreased vitamin C:

1. 1. Prolonged deficiency leads to Scurvy.
   2. There is an inadequate formation of intercellular substances in the connective tissue leads to:
      1. Swollen, tender, and sometimes bleeding into the joints.
      2. Gums are swollen.
   3. Infantile scurvy also knew Barlow’s disease, will show bayonet rib syndrome.
   4. There is vascular fragility leads to:
      1. Cutaneous bleeding and usually starts in the lower thigh and may spread to buttocks, abdomen arms, and legs.
      2. Petechial hemorrhage may lead to a large bruise.
      3. There is an ocular hemorrhage.
      4. Bleeding in the GI tract, kidneys, conjunctiva, and brain.
      5. Hemorrhage of the gingiva.
   5. There may be dental loss and even fractures.
   6. There is delayed wound healing.
   7. Other glands like salivary, lacrimal, and parotid may be involved.
   8. There may be femoral neuropathy and edema of lower extremities.
2. Toxicity:
   1. Large doses of vitamin C for allergy and cold are not recommended.
   2. large doses do not cause any problems except GI upset.
   3. Increased oxalate stones in the kidney and urinary bladder due to acidification of urine.

Clinical Effects Of Increased Vitamin C:

1. Diarrhea.
2. Nausea.
3. Over absorption of iron.
4. A stone formation like oxalate stones.
5. Effect on diabetes tests and occult blood.

Method To Measure Vit.C:

1. This can be measured by:
   1. Photometric system
   2. Fluorometric and HPLC techniques can be used.

Treatment

•  The daily dose of  10 mg of vit.C is sufficient to treat the clinical signs of scurvy.