Cobas 8000 modular analyser series

Fasting blood samples were obtained as part of the patients' clinical follow-up. Total serum calcium, phosphate and alkaline phosphatase were measured using colorimetric methods. Serum concentrations of 25-hydroxy vitamin D (25-OHD) and serum carboxy-terminal collagen crosslinks (CTX) were measured using automated chemiluminescence immunoassay systems (Cobas 8000 modular analyser series, Roche Diagnostics; iSYS, Immunodiagnostic Systems). The Quidel enzyme immunoassay (San Diego, CA, USA) was used to determine bone alkaline phosphatase (BAP) levels. BAP and CTX serum concentrations were converted to age- and gender-specific Z-scores based on published reference data (Koay et al., 2004 (link)). The following cut-off points were used for the serum 25-OHD levels: sufficiency above 75 nmol/L (>30 ng/mL), insufficiency between 50 and 75 nmol/L (20–30 ng/mL) and deficiency below 50 nmol/L (<20 ng/mL).

Following approved ethical guidelines from the local ethics review committee complete blood count and biochemical assessment results were obtained from the Haematology Laboratory at UHG. The data set received in 2018–2019 (discovery data set) was considered as discovery data set while the data set received in 2020–2021 (validation data set) was used to validate the results. The samples were analysed to determine changes in biochemical parameters such as serum Urea, Creatinine, Albumin, Total Protein, and serum electrolytes (Sodium, Potassium, Chloride, Phosphate, and Calcium) and haematological parameters or blood cell counts. Using the Advia 212i system, blood counts were done and biochemistry measurements were performed on serum by the Cobas 8000 modular analyser series from Roche Diagnostics. The reports of these tests were compiled for each patient and analysed for normal and abnormal absolute neutrophil counts (ANC). Each patient data obtained was further classified based on ANC into normal and moderate (0.5–1.0 × 10⁹/L ANC) or severe (<0.5 × 10⁹/L ANC) neutropenia. The patient data was then analysed to determine changes in biochemical parameters such as serum Urea, Creatinine, Albumin, Total Protein, and serum electrolytes (Sodium, Potassium, Chloride, Phosphate, and Calcium) which were correlated with changes in neutrophil counts.