Difference between revisions of "Hyperthyroidism"

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*In young animals causes accelerated maturation of growth plate
 
*In young animals causes accelerated maturation of growth plate
*In adults causes [[Bones Degenerative - Pathology#Osteoporosis (Atrophy)|osteoporosis]]
+
*In adults causes [[Osteoporosis|osteoporosis]]
  
  

Revision as of 12:22, 3 March 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.


  • In young animals causes accelerated maturation of growth plate
  • In adults causes osteoporosis


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