Thyroid Disorders 2 Flashcards
Why may thyroid nodules not always be palpable?
Hyperactive thyroid tissue can be situated WITHIN THE THORACIC INLET
What renal changes are seen with hyperthyroidism?
- Hyperthoroid INCREASES GFR
- so when Tx the GFR will DECRESASE and creatinine will INCREASE
- urea is generally higher than creatinine
- hyperthyroidism causes glomerular sclerosis (probably) so will eventually decrease GFR and needs Tx !
How may kidney function be apparently affected by hyperthyroid Tx?
GFR can drop significantly enough that creatinine increases above the ref range
- > apparent renal failure
- initially acute reduction but long term will stay steady
Should the risk of pushing cats into renal failure (Ie. currently non-azotaemic but become azotaemic once hyperthyroidism Tx) discourage you from Tx?
No - survival times no different
> except if you make them HYPOthyroid (they gone die sooner)
> you are NOT causing acute renal failure (CF COMMON KNOWLEDGE) you are changing GFR but will stabilise
General Tx options for hyperthyroidism
> medical - carbimazole - methimazole > surgical ~ unilateral thyroidectomy sequentially 12-15mo - generally no replacement tx neeed ~ bilateral thyroidectomy - generally o replacemetn tx required > thyroid irradiation > diet
Outline medical Tx hyperthyroid
> crbimazole (precursor to methimazole)
- can give either
- higher doses of carbimazole needed initially but less freq dosing
- induction 2-3w
- once controlled maintainance lower
What adverse effects may be seen with medical Tx for hyperthyroid? How common are adverse reactions? Alternative?
> side effects in 5-20% patients
- GIT (VD+ inappetence)
- depression, lethargy, listlessness
- facial pruritis
- blood dyscrasis (anaemia, granulocytopenia, thromboplasias)
- minimal benefit in changing the thiolurea
means medical management canot be used (irrespective of route of administration)
- can get ear creams etc.
Surgical Tx of hyperthyroidism?
> unilateral thyroidectomy
- good for 6-9mo but relapse
replace PT tissue into cervical muscle
bilateral also poss
NB: ectopic thyroid tissue may be present elsewhere in the body
Radioactive Tx for hyperthyroidism
- dose between 110-183 MBq >98% efficacy - 2w stay in hospital - median survival >6.5years - must be off meds min 2w prior to tx (thyroid needs to be active to uptake radioactive stuff)
Dietary Tx of hyperthyroidism
- minimal iodine to limit thyroid hormone production
- exclusive diet so need environmental management
- reported success rate high but questionable use of data and inclusion requirements
- $$$$$
Summary hyperthyroidism currently
- clinical picture variable
- small number of cases will have normal or subnormal T4
- hyperT possible cause of CKD even though correcting hyperT –> ^ creatinine
- hyperT does NOT cause Hypertension (opposite!!! May develop hypertension when treated)
Hypothyroidism Pathogenesis?
> dog disease
not very common
causes
- congenital abnormality or acquired
- congenital d/t enzyme deficiency
- acquired d/t immune mediated destruction of thyroid tissue
- almost never d/t pituitary function problems
Clinical signs of hypothyroidism
- lethargic and disinterested
- may be overweight
- excercise intolerant, muscle and joint pain, gait changes
- dermal changes: alopecia esp primary guard hairs, hyper pigmentation with thickened skin
- long hair may have thicker coat as falling out hair gets trapped - if groomed we’ll see alopecia
- infertility, libido and joint pain
- occasional NEURO problems: vascular infarcts etc.
What is the human term for congenital cerebrocortical development d/t hypothyroidism
Cretinism
How can congenital hypothyroidism be dx?
Marker of biological activity affected by thyroid hormone
- growth plates
- no calcification in epiphyseal centres (EPIPHYSEAL DYSGENESIS)
