Abstract
Simple SummaryParathyroid hormone (PTH) is involved in many metabolic diseases, such as chronic kidney disease (CKD) and calcium disorders, and its measurement could be of clinical utility. However, available methods for the measurement of feline PTH are limited and not widely accessible. The aim of this study was to perform the analytical validation of a new method for PTH measurement in cats. Thirty-eight cats affected with CKD were included. The analytical protocol provided an evaluation of the precision, accuracy, and storage stability at different temperatures. The method investigated showed good precision and accuracy and good stability for 1 week of storage at freezing temperatures. The method was validated in cats, allowing its future use in diagnostic procedures.The determination of parathyroid hormone (PTH) in cats could be of clinical utility in many metabolic disorders, such as renal diseases, hypercalcemia, or nutritional imbalances. However, the available methods for the measurement of feline PTH are limited, not widely available, and need radioimmunoassays. The aim of this study was to perform the analytical validation of a new immunoenzymatic method for the measurement of feline PTH. Thirty-eight cats affected with chronic kidney disease (CKD) were included. PTH was measured using a two-site immunoenzymatic method validated in humans and dogs (ST AIA-PACK® Intact PTH, Tosoh Bioscience, Tessenderlo, Belgium). The analytical validation provided the evaluation of precision (intra-assay and inter-assay), accuracy (linearity under dilution (LUD) and spike recovery test (SRT)), and the storage stability of serum samples at 20 °C, 4 °C, and −20 °C. The method showed good precision (intra-assay CVs (coefficient of variations) 3.19–9.61%; inter-assay CVs 9.26–15.28%). In both the intra- and inter-assays, the highest imprecision was found with the low concentration pool (9.61% and 15.28%) and accuracy (LUD and SRT r2 = 0.99, p < 0.001), while the stability was optimal up until 7 days at −20 °C (−7.7%). The method was successfully validated in cats, allowing its future use in diagnostic procedures.
Highlights
Parathyroid hormone (PTH) is a single-chain, 84-amino-acid polypeptide produced by chief cells in the parathyroid glands and highly conserved among mammalian species; feline parathyroid hormone (PTH) is more than 83% identical to the canine and human molecules [1].PTH is the main regulator of ionized calcium concentration through its direct effects on renal tubular reabsorption and bone resorption of calcium and indirect intestinal absorption of calcium mediated by calcitriol or active vitamin D
As the severity of renal hyperparathyroidism is assumed to increase with the degree of azotaemia, cats at different chronic kidney disease (CKD) stages were included in the study, to increase the probability of obtaining samples with different PTH concentrations [10]
The CKD staging according to the International Renal Interest Society (IRIS) staging system at first examination was as follows: 1 cat was classified in Stage 1, 26 in Stage 2, 4 in Stage 3, and 7 in Stage 4
Summary
Parathyroid hormone (PTH) is a single-chain, 84-amino-acid polypeptide produced by chief cells in the parathyroid glands and highly conserved among mammalian species; feline PTH is more than 83% identical to the canine and human molecules [1].PTH is the main regulator of ionized calcium concentration through its direct effects on renal tubular reabsorption and bone resorption of calcium and indirect intestinal absorption of calcium mediated by calcitriol or active vitamin D. PTH has a role in phosphorus metabolism, increasing bone resorption and decreasing reabsorption in renal tubules [2]. RHPT is secondary to chronic kidney disease (CKD), a common disease in feline medicine affecting especially old cats (30–40% over 10 years) due to different underlying aetiologies; CKD induces many metabolic disorders involving calcium and phosphorus metabolism, resulting in hypersecretion of PTH [3]. The determination of PTH concentrations is a fundamental tool in the diagnosis of calcium metabolism disturbances, in monitoring the treatment response, and in the evaluation of prognosis. In this context, routine measurement of PTH improves the ability to diagnose parathyroid disorders [1,4]. The currently available validated methods for the measurement of feline PTH are limited and not widely available
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