The Role of Growth Hormone in Enchondroplasia and Chondral Osteogenesis: Evaluation by Hand X-ray

Lea Even ¹ Björn Andersson ² Berit Kriström ³ Kerstin Albertsson-Wikland ² Zeev Hochberg ⁴

¹Departments of Pediatric, Western Galilee Hospital Naharia and the Faculty of Medicine, Bar-Ilan University
²Göteborg Pediatric Growth Research Center, Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, Sahlgrenska Academy
³3Department of Clinical Science, Pediatrics
⁴Pediatric Endocrinology, Meyer Children's Hospital, Rambam Medical Center, and Rappaport Faculty of Medicine, Technion – Israel Institute of Technology

Aim
This study aimed to assess the impact of GH on the two processes of bone maturation Background
The process of growth and maturation of long (radius and ulna) and short bones (metacarpals and phalanges) of the hand (enchondroplasia) differs from that for the carpal cuboid bones (chondral osteogenesis). Both processes are under the influence of several hormones and growth factors, with

GH and IGF1 playing important roles

Results

Bone maturation was delayed before the start of GH treatment in all three groups of bones. The delay was greater for the carpal bones (3.2 ± 1.2 'years') compared with the long bones (2.6 ± 1.3 'years'; p=0.0007) and the short bones (1.3 ± 1.1 'years'; p<0.0001) of the hand (Figure 1). The bone age of the carpal cuboid bones and long bones, but not the short bones, matured beyond the expected chronological age change (p<0.0001) during 2 years of GH treatment. At 2 years of GH treatment, the bone age of the carpal bones had matured by 4.2 ± 1.3 'years', that of the long bones by 3.4 ± 1.3 'years', and that of the short bones by 1.9 ± 0.6 'years‘ (Figure 2). .
The delay in bone maturation was greater for the carpal bones in those with GHD than those with ISS (3.6±1.3 vs 3.1±1.1years, respectively; p<0.0001), and normalized at 2 years of GH.
Patients and Methods
Included 95 prepubertal children, 30 GH deficient (GHD) and 65 with idiopathic short stature (ISS), aged 7.4±1.9 (mean±SD) years (TRN 98-0198-033)1. Bone age was assessed according to Greulich and Pyle from X-rays performed at start, and at 1 and 2 years of GH treatment; separately for the carpals, long bones and short bones, and was expressed as years of delay relative to chronological age. Statistics used were Students t-test and ANOVA with Tukey's HSD Post-hoc test.
Conclusions
1. GH therapy accelerates mostly carpal bones (surrogates for the vertebrae), implying that 2. The dominant physiological effect of GH is on chondral osteogenesis with a milder effect on enchondroplasia. 3. A BA profile with mostly delayed carpals is typical for GHD. 4. BA reading must include the carpal bones.