Difference between revisions of "Hyperthyroidism"

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Seen most commonly in the cat.  Elderly cats are affected with the average age of onset being 12-13 years. 
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''Clinical signs'':
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*Weight loss despite polyphagia
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*Increased activity, nervousness (approximately 10% will show apathy)
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*Polyuria and polydipsia
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*Heat intolerance, panting
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*Tachycardia >240 bpm
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*Poor coat, matted and unkempt
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*Palpable thyroid mass often present
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Often see a [[Hypertrophic Cardiomyopathy|hypertrophic cardiomyopathy]] due to chronically increased heart rate and activity.
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[[Image:thyroid adenoma.jpg|right|thumb|125px|<small><center>'''Thyroid adenoma'''. Courtesy of T. Scase</center></small>]]
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''Aetiopathogenesis'':
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>98% are a functional adenoma of the thyroid gland and many will be palpable. 
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''Treatment:''
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Surgical removal of the affected thyroid gland(s).  If bilateral it is important to preserve at least one parathyroid gland to maintain calcium homeostasis. 
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Medical treatment:
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*'''Carbamizole''': Interferes with thyroid hormone synthesis. 
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*'''Radioactive iodine''' therapy.  Useful for intrathoracic thyroid nodules.
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[[Category:To Do - Clinical]][[Category:Endocrine Diseases - Cat]]
 
[[Category:To Do - Clinical]][[Category:Endocrine Diseases - Cat]]
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[[Category:Thyroid Gland - Pathology]]

Revision as of 13:58, 21 February 2011



Seen most commonly in the cat. Elderly cats are affected with the average age of onset being 12-13 years.

Clinical signs:

  • Weight loss despite polyphagia
  • Increased activity, nervousness (approximately 10% will show apathy)
  • Polyuria and polydipsia
  • Heat intolerance, panting
  • Tachycardia >240 bpm
  • Poor coat, matted and unkempt
  • Palpable thyroid mass often present

Often see a hypertrophic cardiomyopathy due to chronically increased heart rate and activity.

Thyroid adenoma. Courtesy of T. Scase

Aetiopathogenesis:

>98% are a functional adenoma of the thyroid gland and many will be palpable.

Treatment:

Surgical removal of the affected thyroid gland(s). If bilateral it is important to preserve at least one parathyroid gland to maintain calcium homeostasis.

Medical treatment:

  • Carbamizole: Interferes with thyroid hormone synthesis.
  • Radioactive iodine therapy. Useful for intrathoracic thyroid nodules.


Pathophysiology

Signalment

Presentation/Clinical Signs

  1. Weight loss
  2. Cardiovascular effects
  3. Palpable goitre
  4. Hyperactive
  5. Polyuria
  6. Polydipsia

Diagnosis

  1. T4 Assay
  2. T4 and TSH assay

Treatment

  1. Surgical - Thyroidectomy
  2. Medical - Thiamazole blocks synthesis of T3 and T4.
  3. Radioactive Iodine