INCREASED PARATHYROID-HORMONE CONCENTRATION IN A SIAMESE KITTEN WITH NUTRITIONAL SECONDARY HYPERPARATHYROIDISM

Clinical, biochemical, radiographic, and hormonal evidence of nutritional secondary hyperparathyroidism (NSH) in a six-month-old male cat fed exclusively a meat baby food diet is presented. Nutrient analysis of the baby food revealed an improper calcium:phosphorous ratio for normal calcium-phosphorous homeostasis. An assay of parathyroid hormone (PTH) and ionized calcium concentrations aided in the diagnosis of NSH when compared to concentrations in age- and sex-matched clinically normal kittens. Data revealed increased PTH concentrations (4 pmol/L) in the NSH cat when compared to controls (<0.37 pmol/L). Ionized calcium remained within normal ranges (1.18 to 1.38 mmol/L) when compared to controls pre- and posttreatment, consistent with the known pathogenesis of NSH. Parathyroid hormone concentrations rapidly returned to control levels after correction of dietary imbalances. Clinical and radiographic signs resolved.