Low growth hormone-binding protein in infants with congenital hypothyroidism.
We evaluated the circulating levels of GH, insulin-like growth factor I (IGF-I), GH-binding protein (GHBP), and IGF-binding protein-3 (IGFBP-3) before L-T4 therapy in 19 infants with congenital hypothyroidism (CH), aged 12-29 days, diagnosed by neonatal screening and in a group of age- and sex-matched control infants. The same parameters were reevaluated after several months of treatment. Serum GHBP was measured by the high performance liquid chromatography-gel filtration method; serum GH, IGF-I, and IGFBP-3 levels were determined by commercial kits. The hypothyroid patients, before beginning therapy, presented significantly lower GHBP values than controls (P < 0.0001); during treatment, these values increased significantly; however, after 6 months they were still significantly lower than control values (P < 0.01). The pretreatment levels of GH were not significantly different from control values; after 1 month of treatment, GH did not show the decrease observed in controls and, therefore, was significantly higher (P < 0.01). The pretreatment levels of IGF-I were not significantly different from control values, but were lower in patients with severe than in those with mild hypothyroidism. They decreased at about 4 months of life and became significantly lower than control values at about 7 months of age (P < 0.05). In conclusion, it may be hypothesized that the condition of CH induces a change in GHBP expression, perhaps beginning in fetal life. The intrauterine production of IGF-I seems to be independent of the levels of GHBP and partially affected by fetal thyroid function.
Cassio
A
A
Department of Pediatrics, University of Bologna, Italy.
Cacciari
E
E
Balsamo
A
A
Colli
C
C
Pasini
A
A
Salvioli
G P
GP
Lanari
M
M
de Iasio
R
R
Boschi
S
S
Pirazzoli
P
P
D002352:Carrier Proteins / Q000097:blood*; D003409:Congenital Hypothyroidism; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy; D007231:Infant, Newborn; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D012016:Reference Values; D013963:Thyroid Hormones / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use
D002352:Carrier Proteins; D018972:Insulin-Like Growth Factor Binding Protein 3; D013963:Thyroid Hormones; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013974:Thyroxine; C051815:somatotropin-binding protein