title: Assessment of calcitonin response to experimentally induced hypercalcemia in cats.
abstract: OBJECTIVE
  To characterize the dynamics of calcitonin secretion in response to experimentally induced hypercalcemia in cats.
  
  
  METHODS
  13 healthy adult European Shorthair cats.
  
  
  METHODS
  For each cat, the calcitonin response to hypercalcemia (defined as an increase in ionized calcium concentration > 0.3 mM) was investigated by infusing calcium chloride solution and measuring circulating calcitonin concentrations before infusion (baseline) and at various ionized calcium concentrations. Calcitonin expression in the thyroid glands of 10 of the cats was investigated by immunohistochemical analysis.
  
  
  RESULTS
  Preinfusion baseline plasma calcitonin concentrations were very low in many cats, sometimes less than the limit of detection of the assay. Cats had a heterogeneous calcitonin response to hypercalcemia. Calcitonin concentrations only increased in response to hypercalcemia in 6 of 13 cats; in those cats, the increase in calcitonin concentration was quite variable. In cats that responded to hypercalcemia, calcitonin concentration increased from 1.3 ± 0.3 pg/mL at baseline ionized calcium concentration to a maximum of 21.2 ± 8.4 pg/mL at an ionized calcium concentration of 1.60 mM. Cats that did not respond to hypercalcemia had a flat calcitonin-to-ionized calcium concentration curve that was not modified by changes in ionized calcium concentration. A significant strong correlation (r = 0.813) was found between the number of calcitonin-positive cells in the thyroid gland and plasma calcitonin concentrations during hypercalcemia.
  
  
  CONCLUSIONS
  Healthy cats had very low baseline plasma calcitonin concentrations. A heterogeneous increase in plasma calcitonin concentration in response to hypercalcemia, which correlated with the expression of calcitonin-producing cells in the thyroid, was identified in cats.
authors.affiliation: Departamento de Medicina y Cirugia Animal, Universidad de Cordoba, Cordoba, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Pineda
authors.forename: Escolastico
authors.initials: E
authors.lastname: Aguilera-Tejero
authors.forename: Ana I
authors.initials: AI
authors.lastname: Raya
authors.forename: Fatima
authors.initials: F
authors.lastname: Guerrero
authors.forename: Mariano
authors.initials: M
authors.lastname: Rodriguez
authors.forename: Ignacio
authors.initials: I
authors.lastname: Lopez
mesh_terms: D000818:Animals; D002112:Calcifediol / Q000097:blood; D002116:Calcitonin / Q000097:blood / Q000378:metabolism*; D002117:Calcitriol / Q000097:blood; D002122:Calcium Chloride / Q000008:administration & dosage / Q000009:adverse effects*; D002371:Cat Diseases / Q000139:chemically induced* / Q000378:metabolism*; D002415:Cats; D005260:Female; D006934:Hypercalcemia / Q000139:chemically induced / Q000378:metabolism / Q000662:veterinary*; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D011863:Radioimmunoassay / Q000662:veterinary; D013961:Thyroid Gland / Q000378:metabolism*
chemical_list: D002116:Calcitonin; D002117:Calcitriol; D002122:Calcium Chloride; D002112:Calcifediol