Vitamin A deficiency (xerophthalmia, retinol deficiency) occurs when there is a lack of vitamin A and carotene in the diet, a violation of its absorption in the intestine and the synthesis of vitamin A from carotene in the body. Vitamin A is found in many products of animal origin (butter, egg yolk, liver, especially some fish and marine animals); In vegetable food products contains carotene, which is provitamin A, from which this vitamin is synthesized in the human body. Vitamin A is fat-soluble. The daily requirement for an adult human is 1.5 mg (5000 IU). Vitamin promotes normal metabolism, growth and development of the body, provides physiological functions of the epithelium of the skin and mucous membranes, sweat, sebaceous and lacrimal glands, the organ of vision.

Clinical picture. Hemeralopia (night, or "chicken", blindness due to dystrophic changes in the retina and optic nerves), xerophthalmia (dryness of the conjunctiva, the formation of whitish opaque plaques), keratomalation (corneal ulceration), hyperkeratosis (dystrophic changes in the epithelium of the skin, mucous membranes and skin Glands - dryness, peeling and pallor of the skin, keratinization of hair follicles, atrophy of sweat and sebaceous glands, etc.), inclinations to pustular skin diseases, infectious lesions of the respiratory system, urination, digestive tract, general malaise, weakness; In children - the growth and development, neurological disorders.

The diagnosis is made on the basis of anamnestic data and a characteristic clinical picture. In the biochemical study of serum, the retinol content for vitamin A deficiency is below 100 μg / l, carotene is lower than 200 μg / l. Ophthalmic examination allows you to determine the time of dark adaptation.

Treatment. Full nutrition with the inclusion of products rich in retinol and carotene, retinol preparations in a daily dose for adults ranging from 10 000 to 100 000 IU / day, depending on the severity of vitamin deficiency for 2-4 weeks under close medical supervision (large doses and uncontrolled treatment can Cause hypervitaminosis A). With hemotheralopia, xerophthalmia and retinitis pigmentosa simultaneously prescribe riboflavin.

Prevention. Diverse food with the inclusion of foods rich in retinol and carotene; In conditions of forced monotonous nutrition - an additional prescription of retinol for 1-2 tablets (3300-6600 ME).