# Parathyroid Hormone Concentration in Dogs Affected by Acute Kidney Injury Compared with Healthy and Chronic Kidney Disease

## TL;DR

This study found that dogs with acute kidney injury (AKI) have elevated parathyroid hormone (PTH) levels, similar to those with chronic kidney disease (CKD), likely due to low calcium and high phosphate levels.

## Contribution

The study is the first to report PTH concentrations in canine AKI, revealing parallels with CKD and human AKI.

## Key findings

- PTH concentrations were significantly higher in AKI and CKD dogs compared to healthy dogs.
- 88.6% of AKI dogs had increased PTH levels, which correlated with higher serum creatinine and phosphate.
- PTH was not useful for differentiating between AKI and CKD in dogs.

## Abstract

This study aimed to investigate parathyroid hormone (PTH) status during canine acute kidney injury (AKI); while renal secondary hyperparathyroidism (RSHPT) is known to be a consequence of chronic kidney disease (CKD), there are no data regarding PTH concentrations in AKI patients, to date. Including three study groups, e.g., healthy patients, AKI patients and CKD dogs, respectively, biochemical parameters and PTH concentrations were compared between study groups. The PTH concentrations were significantly higher in both the AKI and CKD groups compared to healthy patients but without significant differences between these two latter study groups. In the AKI group, increased PTH concentrations were detected in 88.6% of dogs. Based on the results of this study, higher PTH concentrations also occurred in canine AKI, presumably as a result of the ionized hypocalcemia and hyperphosphatemia reported in these patients. On the other hand, PTH was not a useful tool for distinguishing AKI from CKD patients. The novelty of these data should be considered as a first step to a better understanding of PTH concentrations in canine AKI, knowing that future prospective studies are needed to better elucidate PTH kinetics over time in these patients.

Information about parathyroid hormone (PTH) status in the course of AKI is lacking. In contrast, renal secondary hyperparathyroidism (RSHPT) is a well-known consequence of canine chronic kidney disease (CKD). This study aimed to investigate PTH status in dogs affected by AKI, comparing PTH concentrations between healthy dogs, dogs affected by AKI and dogs affected by CKD. Three groups of dogs (35 affected by AKI, 35 affected by CKD and 41 healthy) were retrospectively included. PTH concentrations were significantly higher in both the AKI and CKD groups (p < 0.0001) compared to healthy ones but without significant differences between the AKI and CKD groups. In the AKI group, increased PTH was detected in 88.6% of dogs. Moreover, in AKI dogs, PTH increases with AKI grading and is correlated with serum creatinine (p < 0.0001; r = 0.67) and phosphate concentrations (p < 0.0001; r = 0.74). PTH in AKI dogs was not correlated with total calcium (tCa), while it was negatively correlated with ionized calcium (iCa) (p < 0.0037; r = −0.53). Higher PTH concentrations also occurred in canine AKI, as reported in canine CKD and human AKI, presumably as a rapid response to ionized hypocalcemia and hyperphosphatemia, frequently reported in our patients. PTH seems not to be a useful tool in distinguishing AKI and CKD.