Low plasma zinc and iron in pica

To determine role of trace elements in causation of pica with specific reference to zinc and iron we studied plasma levels of iron (Fe), Zinc (Zn), calcium (Ca) and magnesium (Mg) and blood lead (Pb) levels by atomic absorption spectrophotometer in 31 children with pica (Pica Group) and 60 controls matched for age, sex and nutrition (Control Group) in an observational case and control study in the settings of outpatient clinic of a tertiary care, teaching hospital.

Data from each group were further stratified by hemoglobin level <9 and >9 g/dl into two subgroups pica-1 and pica-2, and control-1 and control-2 respectively, to control for confounding effect of iron deficiency anemia.

The plasma Fe level (mean +/- SD) in children with pica (42.7 +/- 9.2) mg/dl) was about 20% lower than that in controls (51.5 +/- 10.0 mg/dl, p < 0.001). Plasma Zn levels in the pica group (60 +/- 4.4 mg/dl) was about 45% lower than those in controls (110.2 +/- 8.5 mg/dl, p<0.001). Correlation of Zn and Fe levels with pica-related variables such as age at onset, duration and frequency and number of inedible objects ingested was not significant.

These findings suggest that hypozincemia with low iron levels may be the possible cause of pica and contradict the contention that low levels of plasma Zn and Fe could be an effect of pica.