Felis ISSN 2398-2950

Renal secondary hyperparathyroidism

Synonym(s): Rubber jaw, Renal rickets, Renal osteodystrophy

Contributor(s): Penney Barber, Audrey K Cook

Introduction

  • Excessive production of parathyroid hormone (PTH).
  • Cause: hyperphosphatemia secondary to renal compromise results in formation of complexes with calcium   →   compensatory increased PTH synthesis. Concurrent deficiency in calcitrol (active vitamin D) is involved in the pathogenesis.
  • Signs: pain, facial swelling, osteopenia, pathological fractures, signs of renal failure Kidney: chronic kidney disease.
  • Diagnosis: signs, laboratory tests, radiography.
  • Treatment: manage CRF, attempt to reduce hyperphosphatemia.
  • Prognosis: generally guarded.

Pathogenesis

Etiology

  • Severe renal dysfunction (congenital > acquired).

Predisposing factors

General

  • Age.

Pathophysiology

  • Reduced glomerular filtration    →   reduced phosphorous excretion   →    hyperphosphatemia Hyperphosphatemia    →    soft tissue mineralization   →    lowering of [blood calcium] Blood biochemistry: total calcium.
  • Reduced intestinal absorption of calcium due to defective vitamin D metabolism in CRF   →    hypocalcemia Hypocalcemia.
  • Hypocalcemia   →    hypertrophy of parathyroid glands   →    increased PTH secretion PTH assay.
  • Decreased active vitamin D   →    stimulates PTH secretion.
  • PTH   →    increased osteoclastic activity   →    bone resorption.

Timecourse

  • Weeks to months.

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.
  • Finch N C, Syme H M, Elliott J (2012) Parathyroid hormone concentration in geriatric cats with various degrees of renal function. JAVMA 241 (10), 1326-1335 PubMed.
  • Hostutler R A, DiBartola S P, Chew D J et al (2006) Comparison of the effects of daily and intermittent-dose calcitriol on serum parathyroid hormone and ionized calcium concentrations in normal cats and cats with chronic renal failure. JVIM 20 (6), 1307-1313 PubMed.
  • Barber P J, Rawlings J M, Markwell P J et al (1999) Effect of dietary phosphate restriction on renal secondary hyperparathyroidism in the cat. JSAP 40 (2), 62-70 PubMed.


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