Canis ISSN: 2398-2942

Hyperparathyroidism (primary)

Contributor(s): Penney Barber, David Bruyette, Audrey K Cook

Introduction

  • Autonomous and excessive secretion of parathyroid hormone (PTH) → hypercalcemia.
  • Cause: tumor of parathyroid gland, usually adenoma - rarely carcinoma.
  • Signs: associated with subsequent hypercalcemia, ie polyuria, polydipsia.
  • Diagnosis: laboratory data, imaging, 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.
  • The caudal pair are embedded in thyroid tissue.
  • In normal animal PTH is secreted in response to low [serum 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 for 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.
  • Milovancey M, Schmiedt C W (2013) Preoperative factors associated with postoperative hypocalcemia in dogs with primary hyperparathyroidism that underwent parathyroidectomy: 62 cases (2004-2009). JAVMA 242 (4), 507-515 PubMed.
  • Arbaugh M, Smeak D, Monnet E (2012) Evaluation of preoperative serum calcium concentrations of ionized calcium and parathyroid hormone as predictors of hypocalcemia following parathyroidectomy in dogs with primary hyperparathyroidism: 17 cases (2001-2009). JAVMA 241 (2), 233-236 PubMed.
  • Feldman E C, Hoar B, Pollard R, Nelson R W (2005) Pretreatment clinical and laboratory findings in dogs with primary hyperparathyroidism: 210 cases (1987-2004). JAVMA 227 (5), 756-761 PubMed.
  • Long C D, Goldstein R E, Hornoff W J, Feldman E C, Nyland T G (1999) Percutaneous ultrasound-guided chemical parathyroid ablation for treatment of primary hyperparathyroidism in dogs. JAVMA 215 (2), 217-221 PubMed.


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