Abstract

Bone resorption processes can be quantified by measuring the urinary deoxypyridinoline (DPD) levels. We evaluated a new, automated chemiluminescence DPD assay (Immulite® Pyrilinks®-D; DPC), compared it with a DPD ELISA (Pyrilinks®-D; Metra Biosystems) and determined the DPD reference ranges for healthy children and adults. The intraassay imprecision of the Immulite DPD assay gave a coefficient of variation (CV) of 5.5 to 8.6%; the interassay CV was 8.0 to 9.5%. The creatinine measurement increased the imprecision of the DPD values per mmol creatinine (Cr). The DPD values measured with Immulite® Pyrilinks®-D showed a clear correlation with the DPD values measured by Pyrilinks®-D ELISA (Rs = 0.98, p < 0.0001). The median of the DPD reference range was high in the 42 prepubertal children (6.0 ± 2.3 years; 29.8 nmol/mmol Cr), and slightly increased in 23 children during puberty (13.7+1.5 years; 37.3 nmol/mmol Cr). It dropped to lower values (10.5 nmol/mmol Cr) in 27 children after puberty (16.5 ± 1.9 years). A median of 4.1 nmol/mmol Cr DPD was measured in the urine of 23 premenopausal, 4.8 nmol/mmol Cr in 14 postmenopausal women, and a median of 5.8 nmol/mmol Cr in 31 adult men. The DPD median in the urine of 23 patients (17 female) with osteoporosis was elevated (8.7 nmol/mmol Cr; p < 0.02). It was strongly elevated in the urine of 5 patients with Osteogenesis imperfecta to 29.8 nmol/mmol Cr (p < 0.01), corresponding to levels usually observed in prepubertal children. In conclusion, the automated chemiluminescence DPD assay measures DPD with high precision and recovery and is easier to handle than the DPD ELISA. DPD urinary excretion in healthy individuals is age-dependent and rises above the reference range in bone diseases associated with increased bone resorption.

DOI: Clin. Lab. 1999;45:423-428