Vitamin A (Retinol) Deficiency: Clinical Presentations, Diagnosis, Treatment, And Toxicity
Bitot's Spots In Night blindness
The earliest symptom is night blindness, followed by degenerative changes in the retina. The bulbar conjunctiva becomes dry, and rough grayish triangular foamy raised patches appear (Bitot’s spots). A solution of 1% Rose Bengal instilled into the eye stains Bitot’s spots dark pink and make them stand out prominently. Both night blindness and xerosis of the conjunctiva readily disappear on administering vitamin A. When the cornea also becomes dry and lusterless, it is called xerophthalmia. More serious complications are keratomalacia involving the cornea with ulceration and necrosis. These changes follow if xerophthalmia is left untreated. Keratomalacia is more common in children aged 1 to 5 years. It leads to perforation, prolapsed of the iris and endophthalmitis leading to blindness. Skin changes include dryness and hyperkeratosis. A variety of intantile hydrocephalus has been attributed to vitamin A deficiency.
Vitamin A deficiency should be suspected in all malnourished children. Normal serum level of vitamin A is 20 ug/dl. Serum levels less than 10 ug/dl are indicative of deficiency.
Treatment: The diet should contain at least 100 g of green vegetables and adequate amounts of animal products. Occurrence of vitamin A deficiency in 5% or more of the population calls for mass treatment. In poor communities, 60 mg retinol administered orally once in 6 months or 300,000 IU once a year under supervision has been found to be extremely useful. Vitamin A deficiency occurring during pregnancy and lactation leads to poor vitamin A stores in the fetus and low vitamin A content of breast milk. These can be prevented by adequate supplementation during pregnancy.
Vomiting In Overdose Of Carotene
Overdose Of Carotene
Excessive intake of carotene containing foods, principally carrots, leads to hypercarotenemia. It is a cosmetic problem due to yellowish pigmentation of skin. The serum is yellow, but sclera is white. The pigmentation disappears with the elimination of excessive carotene from the diet. Hypothyroid patients are very susceptible to hypercarotenemia. Hypercarotenemia does not lead on to hypervitaminosis A.
Vitamin A toxicity: This may be due to self- medication or large scaled ingestion of livers of fish or polar having enormous quantities of vitamin A.
Acute toxicity: Symptoms include abdominal pain, nausea, vomiting, headache and desquamation of the skin. Recovery occurs spontaneously on removing the source of the vitamin from the diet.
Chronic toxicity: this is seen in people who take 40,000 units or more of vitamin A daily for a prolonged period. It is characterized by body aches, arthralgia, hair loss, anorexia, benign intracranial hypertension, weight loss and hepatomegaly.
Clinical diagnosis can be confirmed by demonstrating raised vitamin A concentration in the serum and normal retinol binding protein. Withdrawal of the vitamin from the diet brings about prompt relief.
© 2014 Funom Theophilus Makama