[1] Univ Pittsburgh, Med Ctr, Renal Electrolyte Div, Pittsburgh, PA 15213 USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Epidemiol, Baltimore, MD USA
[3] Johns Hopkins Univ, Sch Med, Dept Pediat, Baltimore, MD 21205 USA
[4] Univ N Carolina, Dept Psychiat, Chapel Hill, NC USA
[5] Univ N Carolina, Clin Ctr Study Dev & Learning, Chapel Hill, NC USA
[6] Univ Alabama Birmingham, Sch Med, Dept Pediat, Birmingham, AL USA
[7] Childrens Mercy Hosp, Dept Pediat, Kansas City, MO 64108 USA