Hypercalcemia following renal transplantation in a cat

An 11-year-old 3.0-kg (6.6-lb) neutered male Persian was referred for renal transplantation. Serum total calcium concentration was slightly high prior to surgery, but the week after surgery, total and ionized calcium concentrations were extremely high, and a small mass was palpable on the right side of the trachea at the level of the thyroid and parathyroid glands. Exploratory surgery of the ventral aspect of the neck was performed, and a right external parathyroid mass was removed. One hour after surgery, the serum ionized calcium concentration was within reference limits, and the serum calcium concentration remained normal for the next 14 months without any specific treatment. The gross and histologic appearance of the mass, combined with the rapid decrease in serum calcium concentration following its removal, confirmed that the mass was a functional parathyroid adenoma. Although a common postoperative complication in people, hypercalcemia following renal transplantation appears to be a rare complication in cats. Surgery should be considered if the condition is a result of a parathyroid adenoma.