title: Renal handling of phosphate can predict height velocity during growth hormone therapy for short children.
abstract: Renal tubular reabsorption of phosphate in response to GH administration was studied in 28 short Japanese children, aged 5-11 yr (height SD score, less than -2.0 SD). Three groups included a classical GH deficiency (group 1; n = 12), a partial GH deficiency (group 2; n = 7), and children with non-GH deficiency (group 3; n = 9), depending on the peak response of serum GH in four provocative tests. Serum phosphorus, alkaline phosphatase, insulin-like growth factor-I (IGF-I), osteocalcin, and ratio of the maximum tubular reabsorption rate for phosphorus to the glomerular filtration rate (Tmp/GFR) were all significantly lower in group 1 compared with findings in groups 2 and 3 (P less than 0.05, P less than 0.01, and P less than 0.001). After the administration of GH (0.1 U/kg.day) for 4 consecutive days, increments in serum phosphorus and Tmp/GFR were significantly higher in group 1 than in group 2 (P less than 0.01 and P less than 0.01) or group 3 (P less than 0.01 and P less than 0.01), whereas the increment in IGF-I was similar in all 3 groups, and the levels of serum alkaline phosphatase and osteocalcin remained unchanged in all 3 groups. The calculated ratio of the increment in Tmp/GFR to the increment in IGF-I (delta Tmp/GFR/delta IGF-I) was highest in group 1, intermediate in group 2, and lowest in group 3 (P less than 0.001). One year after the GH treatment (0.5 U/kg.week), height velocity was 7.9 +/- 2.2 cm/yr in group 1 and 5.9 +/- 1.2 cm/yr in group 2; no child in group 3 was treated. When the above calculated parameters, delta Tmp/GFR/delta IGF-I and increment in height velocity (difference between pre- and posttherapy values), were taken into account, there was a significant positive correlation (n = 19; r = 0.78; P less than 0.001). This parameter can be used for purposes of predicting the outcome after 1 yr of GH therapy.
authors.affiliation: Department of Pediatrics, Kumamoto University Medical School, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Nishiyama
authors.forename: M
authors.initials: M
authors.lastname: Ikuta
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: S
authors.initials: S
authors.lastname: Tomoeda
authors.forename: I
authors.initials: I
authors.lastname: Matsuda
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D001827:Body Height / Q000187:drug effects / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology; D006128:Growth / Q000187:drug effects / Q000502:physiology*; D006130:Growth Disorders / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D013006:Growth Hormone / Q000172:deficiency / Q000627:therapeutic use*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D007668:Kidney / Q000378:metabolism / Q000502:physiology*; D015675:Osteocalcin / Q000097:blood; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000097:blood; D013997:Time Factors
chemical_list: D010710:Phosphates; D015675:Osteocalcin; D010758:Phosphorus; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D000469:Alkaline Phosphatase