Pica and mineral status in the mentally retarded

A study population consisting of 66 mentally retarded individuals, 60 with and six without pica, was evaluated for iron status, and for plasma and hair zinc, copper, and magnesium levels within a month of known dietary intake. The parameters were all within the normal range for individuals without pica. In contrast, subjects practicing pica had low plasma zinc and elevated plasma copper values as compared to those without pica. Plasma magnesium was in the low normal range for all individuals in the study population. Among the indicators of iron status measured, Hb, hematocrit, plasma iron, total iron-binding capacity, iron saturation, and plasma ferritin, several values were low (p less than 0.001). Depression in plasma zinc level was related to the type and severity of the pica. In plasma, zinc was positively correlated with iron and negatively correlated with copper. No relationships were found between dietary intakes and plasma levels of these minerals. The data suggest that malabsorption of zinc and iron were associated with some types of pica although the individuals received adequate dietary intake of minerals. Zinc, copper, and magnesium concentrations in hair were within normal ranges. Hair was a less sensitive indicator than plasma of trace element status.