Measurement of biochemical markers of bone formation and bone resorption is an easily accessible method of non-invasive evaluation of bone turnover. Markers of bone formation are products of metabolic activity of osteoblasts and markers of bone resorption are products of type I collagen breakdown by osteoclasts. Markers of bone turnover are widely used in both children and adults. In pediatric endocrinology bone turnover markers are considered as useful tools for predicting effects of growth hormone (GH) therapy.

Evaluation of bone turnover markers and their usefulness in predicting the effects of treatment in children with growth hormone deficiency during the first year of growth hormone therapy.

The studied group consisted of 27 children with growth hormone deficiency qualified for growth hormone treatment according to applicable criteria. This was a prospective study and covered a period of at least six months before and the first year of growth hormone treatment. The mean age in the studied group was 12.09 ± 3.08 years (5.08-16.0 years). After the first year of treatment pubertal development across the studied group did not exceed Tanner stage 3. Mean GH dose was 0.183 mg/kg/week (0.15-0.21 mg/kg/week). Permission to conduct the study was obtained from the Bioethics Committee of the Medical University of Warsaw. Evaluation of patients included anthropometric measurements and biochemical blood tests. Anthropometric measurements were performed according to current standards at baseline and at 3, 6 and 12 months of growth hormone treatment (1). Body height was standardized in accordance with growth charts published by the Institute for Mother and Child in 2001 for Warsaw children (2). Growth velocity before treatment was calculated based on data from the period of 6-18 months before the start of therapy. The following bone turnover markers were measured in the blood: three markers of bone formation, namely alkaline phosphatase (ALP), bone alkaline phosphatase (b-ALP), procollagen I carboxyterminal propeptide (PICP) and one marker of bone resorption cross-linked carboxyterminal telopeptide of type I collagen (ICTP). Measurements were made at baseline and at 3 and 6 months of treatment. ALP and b-ALP were measured on a Vitros 250 by dry chemistry using Ortho-Clinical Diagnostics reagents (Johnson & Johnson, China, Hong Kong) (reference ranges – prepubertal girls and boys: 150-420 U/L, pubertal girls: 70-560 U/L, pubertal boys: 130-530 U/L). PICP and ICTP μg/L were measured by radioimmunoassay (RIA) using UniQ PICP RIA kit and UniQ ICTP RIA kit (Orion Diagnostica, Finland, Espoo) (reference ranges – PICP: children aged 4-16 yrs 330 ± 130 μg/L, ICTP: prepubertal children 7-16 μg/L, pubertal girls 6-16 μg/L, pubertal boys 8-23 μg/L).