Low serum Zn has been reported in SCD and has been associated with short stature and delayed sexual development. Zn may also interfere with Cu absorption. The objective of this study was to examine the relation between Zn and Cu status and growth and body composition abnormalities in children with SCD.

104 children, ages 0-18 y, with SS type SCD participated in the study while in their usual state of good health. Measures included height (HT), weight(WT), arm circumference, triceps skinfold thickness and elbow breadth. Upper arm muscle area (UAMA) was calculated from arm and skinfold measurements. Fat-free mass (FFM) and fat mass (FM) were estimated by total body electrical conductivity (TOBEC). Z scores were computed for FFM and FM from within this SCD sample; the remainder of Z scores were calculated from National Center for Health Statistics reference data. Blood values included complete blood count, serum Zn, Cu, and alkaline phosphatase. Skeletal maturation was assessed by hand-wrist X-ray and scored by the TWII method and sexual maturation by Tanner score.

The children were grouped according to serum Zn level. 44% had low serum Zn(< 70 mcg/dl) (Group I). The remainder were normal (70-150 mcg/dl) (Group II). Both groups had evidence of poor growth. Group I had lower values (Mean± SE) than Group II for HT-Z (-0.78 ± 0.15, -0.15 ± 0.14, p=0.003), WT-Z (-1.00 ± 0.15, -0.14 ± 0.13, p=0.003), UAMA-Z(-0.51 ± 0.13, -0.15 ± 0.12, p=0.045), FFM-Z (-0.21 ± 0.16, 0.27 ± 0.14, p=0.025), and elbow breadth-Z scores (-0.66 ± 0.14, -0.19 ± 0.13, p=0.017),respectively. There were no significant group differences in age, gender, WT for HT, triceps, FM, skeletal or sexual maturation, hematologic indices, Cu or alkaline phosphatase. Similar analyses were completed with serum Cu: 28% had normal serum Cu for age, the remainder were elevated. Cu status was only associated with reticulocyte count, the increased Cu group had higher reticulocyte count (p=0.021).

Further studies are indicated to determine the etiology of the decreased serum Zn values and the role for Zn supplementation to improve growth and body composition in children with SCD. The demonstration of normal to increased serum Cu here may increase the margin of safety for Zn supplementation. Supported by NHLBI (38633-06) and GCRC (M01RR00240).