Reference interval determination for parathyroid hormone, ionized calcium, and total calcium concentrations in the...

To establish reference values for intact parathyroid hormone (PTH), ionized calcium (iCa) using both whole blood and serum samples, and serum total calcium in domestic rabbits.

Blood samples were collected at a private veterinary hospital from clinically healthy client-owned, mixed-breed, mixed-sex, adult (1 to 7 years of age) rabbits using manual restraint over a 5-month period. Complete blood count, serum biochemical analysis, and i-STAT were performed for each sample. Serum iCa and intact PTH concentrations were analyzed by the Michigan State University Veterinary Diagnostic Laboratory. Reference value intervals and descriptive statistics for intact PTH, iCa, and serum calcium were established per the guidelines of the American Society for Veterinary Clinical Pathology.

Reference intervals for PTH (0.50 to 5.90 pmol/L), serum total calcium (12.60 to 16.50 mg/dL), iCa using whole blood on i-STAT (1.35 to 1.82 mmol/L), and iCa using serum on a benchtop analyzer (1.53 to 1.84 mmol/L) were established from a population of 50 rabbits. In this population of rabbits, there was a statistically significant difference between the whole blood iCa (1.64 ± 0.10 mmol/L; mean ± SD) and the serum iCa (1.70 ± 0.07 mmol/L); however, the difference is likely clinically insignificant.

This is the first study to establish reference intervals for intact PTH via chemiluminescent analysis in the domestic rabbit.

Determining inappropriate increases or decreases in PTH and calcium is crucial for antemortem diagnosis and treatment of primary and secondary disorders of calcium.