RENAL SECONDARY HYPERPARATHYROIDISM IN A CAT

The progression of chronic renal failure in an 18-year-old castrated m ale domestic short-hair cat was documented over a five-year period. Th e moderate azotemia present in this patient was neither preceded by no r occurred concurrently with hyperphosphatemia or hypocalcemia. Howeve r, marked renal secondary hyperparathyroidism (SHP) occurred. Renal SH P was suggested initially by the presence of bilateral palpable nodule s in the area of the thyroid and parathyroid glands that was not assoc iated with an elevation of serum thyroxine concentration. The diagnosi s of renal SHP was made based on measurement of serum intact parathyro id hormone and necropsy and histopathology. This case illustrates that the classical findings of hyperphosphatemia and hypocalcemia are not necessary for the development of renal SHP Calcitriol (1,25-dihydroxyv itamin D3) is more likely to regulate parathyroid cell function than e xtracellular calcium in chronic renal failure.