Vitamin A deficiency (Bitot spot)
 


What this section contains?

Vitamin A deficiency (Bitot spot)

What is Vitamin A deficiency (Bitot spot)?

Bitot's spots are the buildup of keratin located superficially in the conjunctiva of human's eyes. They can be oval, triangular or irregular in shape. The spots are a sign of vitamin A deficiency and associated with drying of the cornea.

Vitamin A helps in development of visual function of the eye. It also helps in building up immunity in the body. Its deficiency can cause Night blindness, which may further progress to Bitot's spot. If untreated, night blindness can lead to permanent blindness. Clinical prevalence of Vitamin A deficiency is less than 1% in India but biochemical prevalence is quite high. Prevalence of Bitot's spot is around 0.6 - 0.7% in children.

Cause

In addition to dietary problems, other causes of VAD are known. Iron deficiency can affect vitamin A uptake; other causes include fibrosis, pancreatic insufficiency, inflammatory bowel disease, and small-bowel bypass surgery. Protein energy malnutrition is often seen in VAD; suppressed synthesis of retinol binding protein (RBP) due to protein deficiency leads to reduced retinol uptake. Excess alcohol consumption can deplete vitamin A, and a stressed liver may be more susceptible to vitamin A toxicity. People who consume large amounts of alcohol should seek medical advice before taking vitamin A supplements. In general, people should also seek medical advice before taking vitamin A supplements if they have any condition associated with fat malabsorption such as pancreatitis, cystic fibrosis, tropical sprue, and biliary obstruction. Other causes of vitamin A deficiency are inadequate intake, fat malabsorption, or liver disorders. Deficiency impairs immunity and hematopoiesis and causes rashes and typical ocular effects (e.g., xerophthalmia, night blindness).

Diagnosis & Tests

Initial assessment may be made based on clinical signs of VAD. Conjunctival impression cytology can be used to assess the presence of xerophthalmia which is strongly correlated with VAD status (and can be used to monitor recovery progress). Several methods of assessing bodily vitamin A levels are available, with HPLC the most reliable. Measurement of plasma retinol levels is a common laboratory assay used to diagnose VAD. Other biochemical assessments include measuring plasma retinyl ester levels, plasma and urinary retonioic acid levels, and vitamin A in breast milk.

Prevention & Risk Factors

Take Vitamin A containing food in sufficient amount

Treatments & Therapies

Treatment of VAD can be undertaken with both oral vitamin A and injectable forms, generally as vitamin A palmitate.

As an oral form, the supplementation of vitamin A is effective for lowering the risk of morbidity, especially from severe diarrhea, and reducing mortality from measles and all-cause mortality. Vitamin A supplementation of children under five who are at risk of VAD can reduce all-cause mortality by 23%. Some countries where VAD is a public-health problem address its elimination by including vitamin A supplements available in capsule form with national immunization days (NIDs) for polio eradication or measles. Additionally, the delivery of vitamin A supplements, during integrated child health events such as child health days, have helped ensure high coverage of vitamin A supplementation in a large number of least developed countries. Child health events enable many countries in West and Central Africa to achieve over 80% coverage of vitamin A supplementation. According to UNICEF data, in 2013 worldwide, 65% of children between the ages of 6 and 59 months were fully protected with two high-dose vitamin A supplements. Vitamin A capsules cost about US$0.02. The capsules are easy to handle; they do not need to be stored in a refrigerator or vaccine carrier. When the correct dosage is given, vitamin A is safe and has no negative effect on seroconversion rates for oral polio or measles vaccines. However, because the benefit of vitamin A supplements is transient, children need them regularly every four to six months. Since NIDs provide only one dose per year, NIDs-linked vitamin A distribution must be complemented by other programs to maintain vitamin A in children. Maternal high supplementation benefits both mother and breast-fed infant: high-dose vitamin A supplementation of the lactating mother in the first month postpartum can provide the breast-fed infant with an appropriate amount of vitamin A through breast milk. However, high-dose supplementation of pregnant women should be avoided because it can cause miscarriage and birth defects.