Felis ISSN 2398-2950

Primary hyperparathyroidism

Contributor(s): Penney Barber, Audrey K Cook

Introduction

  • Autonomous and excessive secretion of parathyroid hormone (PTH)   →   hypercalcemia.
  • Rare in cats.
  • Cause: tumor of parathyroid gland, usually adenoma - occasionally carcinoma.
  • Signs: associated with subsequent hypercalcemia.
  • Diagnosis: laboratory data, histopathology.
  • Treatment: parathyroidectomy.
  • Prognosis: good following complete removal of affected parathyroid gland.

Pathogenesis

Predisposing factors

General

  • Four parathyroid glands in two pairs in cervical area.
  • One pair are embedded in thyroid tissue, although position of all glands very variable.
  • In normal animal PTH is secreted in response to low [serum calcium] Blood biochemistry: total calcium and results in:
    • Reduced renal calcium excretion.
    • Increased renal phosphate excretion.
    • Increased renal vitamin D activation and subsequent increased intestinal calcium uptake. 
    • Bone resorption, via activation of osteoclasts.
  • Autonomous PTH secretion from an abnormal gland   →   hypercalcemia.

Pathophysiology

  • Autonomous PTH secretion   →   hypercalcemia   →   clinical signs.

Timecourse

  • Months.
  • Animals often have long-term histories of vague illness.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Sueda M T & Stefanacci J D (2000) Ultrasound evaluation of the parathyroid glands in two hypercalcemic cats. Vet Rad Ultrasound 41 (5), 448-451 PubMed.
  • Kallet A J, Richter K P, Feldman E C et al (1991) Primary Hyperparathyroidism in cats - 7 cases (1984-1989). JAVMA 199 (12), 1767-1771 PubMed.


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