Table 1.

Subject Characteristics

Number	258
Gender (M:F)	155:103
Race/ethnicity (white:black:Hispanic:Asian)	181:57:14:3
Age at baseline, years (range)	0.2 – 19.8
Height SDS [median (interquartile range)]	0.3 (−0.5 – 0.8)*
BMI SDS [median (interquartile range)]	0.2 (−0.4 – 0.8)**
Number that returned for second visit	139
Time between visits, months (range)	2.4 – 11.9
Height velocity, cm/y (range)	0 – 26.9
Height velocity SDS [median (interquartile range)]	0.1 (−1.6 – 1.4)
Number that had second blood sample	94
Total number of blood samples	352

^*differs from general US population, p<0.005

^**differs from general US population, p<0.05