Hypercalcemia in Reptiles | Vetlexicon
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Hypercalcemia


Synonym(s): High calcium levels

Introduction

  • Cause: diet, neoplasia, chronic renal failure, impaired calcium excretion, vitamin D toxicosis.
  • Signs: calciuria, urolithiasis, metastatic calcification of tissues.
  • Diagnosis: biochemistry, diagnostic imaging.
  • Treatment: reduce calcium intake, fluid therapy, treat underlying cause.
  • Prognosis: depends on cause.

Presenting signs

  • Anorexia.
  • Lethargy.
  • Weight loss.
  • Weakness.

Age predisposition

  • Neoplasia more common in older animals.

Gender predisposition

  • Physiological hypercalcemia in female reptiles.

Breed/Species predisposition

  • Uncommon presentation.

Cost considerations

  • Investigations can be costly, prolonged treatment depending on underlying cause.

Special risks

  • Can be associated with renal disease.

Pathogenesis

Etiology

  • Physiological process in reptiles during follicular development.
  • Excessive vitamin D Vitamin D supplementation may lead to hypercalcemia and metastatic calcification of tissues.
  • Primary or secondary hyperparathyroidism.
  • Osteolytic bone tumors.
  • Laboratory error and sample hemolysis should be ruled out.

Predisposing factors

General

  • High calcium diet.
  • High vitamin D Vitamin D in diet or excessive supplementation.
  • Chronic renal failure.

Pathophysiology

  • Hypercalcemia is the result of increased uptake from gastrointestinal system, excessive release from bone, or decreased renal excretion of calcium.
  • Parathyroid hormone activates osteoclasts, with release of calcium from bone. PTH also promotes renal conservation of calcium and stimulate the synthesis of active vitamin D by the kidneys.
  • Vitamin D and its analogues increase gastrointestinal uptake of calcium. At high levels, calcium is also released from bone.
  • Osteolytic processes result in release of calcium and phosphorus from bone.
  • Gravid female reptiles have increased plasma or serum concentrations of calcium that are used as body stores and mobilized during vitellogenesis, yolk production and shell formation:
    • During egg development hypercalcemia occurs in response to estrogen and reproductive activity.
    • The increase is in protein bound calcium.
    • Ionized calcium remains in the normal range.

Timecourse

  • Usually chronic.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

Other sources of information

  • Rendle M & Calvert I (2019) Nutritional Problems. In: BSAVA Manual of Reptiles. 3rd edn. Eds: Girling S J & Raiti P. BSAVA, UK. pp 365-396.
  • Campbell T W (2014) Clinical Pathology. In: Current Therapy in Reptile Medicine and Surgery. Eds: Mader D & Divers S. Elsevier, USA. pp 70-92.