Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues. It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of VAD, as the vitamin has a major role in phototransduction. Xerophthalmia, keratomalacia, and complete blindness can follow if the deficiency is more severe.Vitamin A deficiency is the worlds leading cause of preventable childhood blindness, and is critical to achieving Millennium Development Goal 4 to reduce child mortality. About 250,000 to 500,000 malnourished children in the developing world go blind each year from a deficiency of vitamin A, around half of whom die within a year of becoming blind. The United Nations Special Session on Children in 2002 set a goal of the elimination of VAD by 2010.The prevalence of night blindness due to VAD is also high among pregnant women in many developing countries. VAD also contributes to maternal mortality and other poor outcomes in pregnancy and lactation.VAD also diminishes the ability to fight infections. In countries where children are not immunized, infectious diseases such as measles have higher fatality rates.
It may be due to restricted fluid intake, adverse effect of drug therapy or low salivary rate. Salivary swelling can be seen sometimes.In patients with renal disease, pallor of the oral mucosa can sometimes be noticed due to anaemia caused by reduction of erythropoietin. Uraemia can lead to alteration of platelet aggregation. This situation, combined with the use of heparin and other anticoagulants in haemodialysis, causes the patients to become predisposed to ecchymosis, petechiae, and haemorrhages in the oral cavity. It can also lead to mucositis and glossitis which can bring about pain and inflammation of the tongue and oral mucosa. In addition, patients might also experience altered taste sensations, dysgeusia, and be predisposed to bacterial and candidiasis infections. Candidiasis is more frequent in renal transplant patients because of generalized immunosuppression.In children with renal disease, enamel hypoplasia of the primary and permanent dentition has been observed. The abnormalities of dental development correlate with the age at which metabolic disturbances occur. For example, enamel hypoplasia in the form of white or brown discoloration of primary teeth is commonly seen in young children with early-onset renal disease. Poor oral hygiene, a carbohydrate-rich diet, disease-related debilitation, hypoplastic enamel, low salivary flow rate and long-term medication contribute to increased risk of caries formation. However, the patients usually have low caries activity, particularly in children. This is due to the presence of highly buffered and alkaline saliva caused by the high concentration of urea nitrogen and phosphate in saliva.