Canis ISSN: 2398-2942
Primary hypoparathyroidism
Synonym(s): eclampsia
Contributor(s): David Bruyette
Introduction
- Relatively rare.
- Cause: immune-mediated degenerative or surgical removal of glands.
- Signs: characterized by hypocalcemia + hyperphosphatemia and either transient or permanent PTH insufficiency.
- Eclampsia in late pregnancy or lactation Puerperal tetany.
- Diagnosis: biochemistry.
- Treatment: calcium and vitamin D supplementation.
- Prognosis: fair to good with treatment.
Pathogenesis
Etiology
- Spontaneous:
- Agenesis of parathyroid glands.
- Atrophy of parathyroid glands with prolonged hypercalcemia Hypercalcemia: overview.
- Immune-mediated parathyroiditis.
- Idiopathic: rare ? familial in St. Bernard (may be associated with hypothyroidism Hypothyroidism ).
- Complication of thyroidectomy: removal of, or damage to, parathyroids.
One parathyroid gland is sufficient to prevent occurrence of tetany.
Pathophysiology
- In normal animal release of parathyroid hormone (PTH) from the parathyroid gand is stimulated by a drop in ionized calcium levels.
- PTH increases serum ionized calcium by increasing:
- Calcium resorption from glomerular filtrate.
- Phosphate secretion.
- Osteoclast function thereby increasing bone resorption.
- Vitamin D formation.
- Reduced PTH secretion → decreased serum ionized calcium → increased neuromuscular irritability → tetany and convulsions.
- Excessive panting and hyperventilation during tetany can → respiratory alkalosis → increased protein-bound calcium and reduced ionized calcium → exacerbation of problem.
- Pyrexia may be due to increased muscle activity during tetanic spasm.
Timecourse
- Within days or months of thyroidectomy.
- May be temporary or permanent.
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.
- Wisner E R, Penninck D & Biller D S et al (1997) High resolution parathyroid sonography. Vet Radiol Ultrasound 38 (6), 462-466 PubMed.
- Bruyette D S & Feldman E C (1988) Primary hypoparathyroidism in the dog - report of 15 cases and review of 13 previously reported cases. JVIM 2 (1), 7-14 PubMed.
- Kornegay J N, Greene C E, Martin C, Gorgacz E J & Melcon D K (1980) Idiopathic hypocalcemia in four dogs. JAAHA 16 (5), 723-34 PubMed.
- Sherding R G, Meuten D J, Chew D J, Knaack & Haupt K H (1980) Primary hypoparathyroidism in the dog. JAVMA 176 (5), 439-44 PubMed.