9301. Vitamin A

Vitamin A is a fat-soluble vitamin. It plays a role in the normal functioning of the retina, mucous membranes, and skin, promotes hormone synthesis, and is involved in metabolic processes.

This test is prescribed if hypovitaminosis is suspected (impaired vision at night, dry skin and cornea, or growth retardation) or vitamin A poisoning (vomiting, diarrhea, dry skin and mucous membranes, muscle and bone pain). It is tested in combination with vitamins E, C, and zinc.

Vitamin A is a fat-soluble vitamin found in many foods. Retinol is the main form of vitamin A in the human body. It enters the body with food and is stored in the liver, from where it is released into the blood and transported to tissues as needed. Vitamin A also plays a role in oxidation-reduction processes, the synthesis of steroid and sex hormones, the formation of ocular photoreceptors, and the maintenance of the structure and integrity of the outer surface of the eye and other mucous membranes. It is essential for normal vision, immune system function, embryonic development, the formation of the epithelial layer of the skin, and skeletal formation. The body cannot produce vitamin A and must obtain it from dietary sources. Meat sources provide vitamin A (as retinol), while vegetables and fruits provide carotene (a substance that can be converted into vitamin A by the liver).

Vitamin A is stored in the liver and fatty tissues and can persist for up to a year in healthy adults. The body maintains relatively stable blood levels and releases vitamin A from storage as needed.

Vitamin A deficiency typically results in degenerative changes in the eyes and skin. An early symptom of deficiency is poor adaptation of vision to darkness (night blindness). It's worth noting that excess vitamin A can be toxic.

• If vitamin A deficiency is suspected.
• To diagnose vitamin A intoxication.
• If symptoms such as:
  • night blindness;
  • dry eyes, skin, and hair;
  • ulcers and damage to the cornea – the outer layer of the front of the eye covering the iris and pupil;
  • thickening of the skin and its lesions;
  • grayish spots on the mucous membrane of the eyes (Bitot's spots);
  • repeated infections;
  • anemia.

• Venous blood

In order to exclude factors that may affect the test results, we recommend to follow the preparation rules: