longitudinal circulating levels of insulin-like growth factor i ( igf-i ) were measured by radioimmunoassay after acid/ethanol extraction of serum or plasma in 44 appropriate-for-gestational age ( aga ) premature infants , 7 small-for-gestational age ( sga ) premature infants and 9 aga full-term infants .
C0229671
serum
C0032105
plasma