Evaluation of essential trace and toxic elements in biological samples of normal and night blindness children of age groups 3-7 and 8-12 years.

The most common cause of blindness in developing countries is vitamin A deficiency. The World Health Organization estimates 13.8 million children to have some degree of visual loss related to vitamin A deficiency. The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence biological samples composition. Vitamin and mineral deficiency prevents more than two billion people from achieving their full intellectual and physical potential. This study was designed to compare the levels of Zn, Mg, Ca, K, Na, As, Cd, and Pb in scalp hair, blood, and urine of night blindness children age ranged 3-7 and 8-12 years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of As, Ca, Cd, K, Pb, Mg, Na, and Zn in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The concentrations of trace and toxic elements were measured by atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The results of this study showed that the mean values of As, Cd, Na, and Pb were significantly higher in scalp hair, blood, and urine samples of male and female night blindness children than in referents (p < 0.001), whereas the concentrations of Zn, Ca, K, and Mg were lower in the scalp hair and blood but higher in the urine samples of night blindness children. These data present guidance to clinicians and other professional investigating deficiency of essential mineral elements in biological samples (scalp hair and blood) of night blindness children.