Ambidirectional cohort study on the agreement of ultrasonography and surgery in the identification of parathyroid pathology, and predictors of postoperative hypocalcemia in 47 dogs undergoing parathyroidectomy due to primary hyperparathyroidism.

Abstract

OBJECTIVE\nTo investigate (1a) agreement of ultrasonographic, surgical, and histopathologic findings in the diagnosis of a neoplastic etiology underlying primary hyperparathyroidism (PHPT), (1b) the ability of ultrasonographically determined parathyroid gland size to distinguish between malignant (carcinoma) and non-malignant (hyperplasia, adenoma) pathology, and (2) variables associated with postoperative hypocalcemia in dogs undergoing surgical treatment of PHPT.\n\n\nSTUDY DESIGN\nAmbidirectional cohort study.\n\n\nANIMALS\nForty-seven client owned dogs with PHPT (34 retrospective; 13 prospective).\n\n\nMETHODS\nData were extracted from medical records. Method agreements were explored using Cohen s Kappa statistic. A receiver operating characteristic curve (ROC) was used to determine a cut-off separating parathyroid pathologies. Univariable and multivariable models assessed associations between postoperative hypocalcemia and potential risk factors.\n\n\nRESULTS\nAgreement of ultrasound and surgery for number and side of affected glands was 31/47 (65.9%) and 34/47 (72.3%), respectively. In 37/47 (78.7%) cases, parathyroid tissue was correctly assessed as pathologic by the surgeon. An ultrasonographic cut-off of ≥8.0\u2009mm (ROC AUC\xa0=\xa00.82) best distinguished malignant from benign pathologies. Dogs with a preoperative serum ionized calcium (iCa) concentration ≥1.75\u2009mEq/L had 7.5 times greater odds of becoming hypocalcemic postoperatively.\n\n\nCONCLUSION\nA fair agreement existed between ultrasonographic and surgical findings in dogs with PHPT. A parathyroid mass ≥8.0\u2009mm on ultrasonographic examination was suggestive of malignancy, while dogs with a preoperative serum iCa concentration ≥1.75\u2009mEq/L were at increased risk for postoperative hypocalcemia in this study.\n\n\nCLINICAL SIGNIFICANCE\nThis study supports the use of bilateral cervical surgical exploration to identify abnormal parathyroid glands for the treatment of PHPT.