Parathyroid hormone

From Dog

Parathyroid hormone (PTH), secreted by the chief cells of the parathyroid glands, causes an increased in serum calcium.

Plasma calcium is regulated within a narrow serum range, by thyroxine, vitamin D and PTH, with mobilization and deposition of calcium from stores in tissue and bone, as well as direct uptake from the gut. Multiple metabolic fragments of PTH in circulation are cleared by glomerular filtration and only intact PTH molecule is metabolically active.

Hypercalcemic dogs with non-parathyroidal disease should have low to low-normal basal PTH. Elevated or high normal PTH in hypercalcemic dog is suggestive of primary hyperparathyroidism or parathyroid carcinoma[1].

Hypocalcemic dogs with non-parathyroidal disease should have high-normal to high basal PTH. Low PTH in hypocalcemic dog is suggestive of primary hypoparathyroidism.

Elevated PTH levels can also be seen in dogs with advance chronic renal disease, ulcerative colitis[2], hypoalbuminemia and cyclosporine use[3].

Other nonparathyroid tissues also produce parathyroid hormone related protein (PTHrp), such as anal sac adenocarcinoma, renal angiomyxoma[4], osteosarcoma[5] and mammary adenocarcinomas[6].

Following parathyroidectomy, levels of PTH drop markedly and calcium and vitamin D supplementation may be required[7].

Normal PTH range in dogs is 2 - 13 pmol/L.

References

  1. Graves TK (2011) When normal is abnormal: keys to laboratory diagnosis of hidden endocrine disease. Top Companion Anim Med 26(2):45-51
  2. Gow AG et al (2011) Hypovitaminosis D in dogs with inflammatory bowel disease and hypoalbuminaemia. J Small Anim Pract 52(8):411-418
  3. Kovalik M et al (2012) Ciclosporin therapy is associated with minimal changes in calcium metabolism in dogs with atopic dermatitis. Vet Dermatol 23(6):481-e491
  4. Gajanayake I et al (2010) Paraneoplastic hypercalcemia in a dog with benign renal angiomyxoma. J Vet Diagn Invest 22(5):775-780
  5. O'Donoghue LE et al (2011) Expression profiling in canine osteosarcoma: identification of biomarkers and pathways associated with outcome. BMC Cancer 10:506
  6. Ogawa B et al (2011) Neuroendocrine carcinoma of the apocrine glands of the anal sac in a dog. J Vet Diagn Invest 23(4):852-856
  7. Graham KJ et al (2012) Intraoperative parathyroid hormone concentration to confirm removal of hypersecretory parathyroid tissue and time to postoperative normocalcaemia in nine dogs with primary hyperparathyroidism. Aust Vet J 90(6):203-209