Comparison of iPTH values in serum and plasma samples depending on the time and temperature in patients with chronic kidney disease

Abstract

Renal osteodystrophy is a systemic disorder associated with chronic kidney disease (CKD) with abnormal values of biochemical parameters related to bone and mineral metabolism. Assessing renal osteodystrophy subtypes is especially important for diagnostic and therapeutic decision. Management of these disorders includes monitoring of homeostasis of calcium, phosphorus and parathormone (PTH). PTH is a significant regulator of mineral balance and it's level is used as a surrogate biomarker for the type of underlying renal osteodystrophy. Worldwide, nephrologists rely on KDIGO - Clinical Practice Guideline for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease - Mineral and Bone Disorder (CKD-MBD) to maintain PTH levels within defined narrow range of optimal values for each stage of CKD and adjust such PTH - lowering treatments as active vitamin D sterols or calcimimetics accordingly. PTH is rapidly degraded in vivo, with half life of 5 minutes and it is also unstable in blood samples. Values can differ significantly when samples are not collected in a standard way and when recommended conditions for transport and sample processing are not followed. It is also important to standardize pre-analytic conditions that may influence the variability in PTH results. The goal of the present study was to compare iPTH stability in serum and plasma samples and evaluate possible pre-analytic errors in sample collection, effect of temperature during transportat and storing prior to Analysis.