Comparison of urinary growth hormone and IGF-I excretion in small- and appropriate-for-gestational-age infants and healthy children.

The output of urinary growth hormone (GH) and IGF-I were quantitated by RIA in 12-h urine collections obtained from infants who were preterm, small for gestational age (PT-SGA, n = 13); preterm, appropriate for gestational age (PT-AGA, n = 27); full term, small for gestational age (FT-SGA, n = 13); and full term, appropriate for gestational age (FT-AGA, n = 29); and from normal children (n = 33). The amounts of GH and IGF-I (mean +/- SEM) excreted by the PT-SGA and FT-SGA infants were not significantly lower than those excreted by the PT-AGA and FT-AGA groups, respectively [GH (micrograms/kg): PT-SGA 13.7 +/- 3.1 versus PT-AGA 14.0 +/- 2.2, FT-SGA 7.8 +/- 2.4 versus FT-AGA 6.6 +/- 1.8; IGF-I (nmol/kg): PT-SGA 0.52 +/- 0.09 versus PT-AGA 0.53 +/- 0.04, FT-SGA 0.31 +/- 0.05 versus FT-AGA 0.35 +/- 0.04]. All infant groups exhibited significantly greater outputs of urinary GH and IGF-I compared with the children (p less than 0.01). The plasma concentrations of GH in all infant groups were high, whereas the plasma IGF-I levels were low. Microalbumin and beta-2 microglobulin excretion did not correlate with urinary GH and IGF-I output. Despite the higher microalbumin output in FT babies, urinary GH and IGF-I excretion was lower in these groups.(ABSTRACT TRUNCATED AT 250 WORDS)