3/3 Thyroid Hormones - Hypothyroidism COMPLETE*** Flashcards
Hypothyroidism: Which species is this more common in?
- Which species is this less common in?
dogs
cats
Hypothyroidism: state the 3 types of Hypothyroidism
primary hypothyroidism
secondary hypothyroidism
tertiary hypothyroidism
Hypothyroidism: Primary
- Where is this hypothyroidism at the level of?
- what about for secondary?
- What about for tertiary?
the thyroid gland
the pituitary
the hypothalamus
Hypothyroidism: Primary Hypothyroidism
- What is wrong with the thyroid gland?
- What 3 types of Primary hypothyroidism are there?
there is a lack of functional thyroid tissue in the gland
acquired
iatrogenic
congenital
Hypothyroidism: Primary
- Which type of Primary hypothyroidism is most common?
- What can this be due to? 3
Acquired
lymphocytic thyroiditis
idiopathic follicular atrophy
neoplasia
Hypothyroidism: Primary - Acquired
- What is lymphocytic thyroiditis?
- What is idiopathic follicular atrophy?
infiltration of lymphocytes and inflammation of the thyroid gland
follicle tissue starting to atrophy
Hypothyroidism: Secondary
- What is happening here?
- What are the 2 possible types of secondary hypothyroidism?
there is impaired secretion of thyroid stimulating hormone from the pituitary gland
acquired
congenital
Hypothyroidism: Secondary - Acquired
- What can cause this? 4
neoplasia
pituitary suppression
illness
malnutrition
Hypothyroidism: Tertiary
- what happens with tertiary hypothyroidism?
the hypothalamus is releasing insufficient thyroid releasing hormone into the hypothalamic paraventricular nuclei
Hypothyroidism: Signalment 2
golden retrievers and cocker spaniels are predisposed
middle aged dogs
Hypothyroidism: State the clinical signs 6
dull
lethargic
exercise intolerance
obesity with no polyphagia
cold intolerance
skin changes
Hypothyroidism: What effect does Hypothyroidism have on the musculoskeletal system? 2
it reduces muscle tone
it changes fibre types
Hypothyroidism: What affect can hypothyroidism have in young animals and why?
growth retardation and short bones because thyroid hormone is needed for normal growth
Hypothyroidism: Why do we get obesity?
less thyroid hormone reduces basal metabolic rate so slows carbohydrate and fat metabolism
Hypothyroidism: What effect does Hypothyroidism have on the cardiovascular system?
- Why?
bradycardia
it decreases cardiac output and contractility
Hypothyroidism: What effect does Hypothyroidism have on the nervous system?
it leads to peripheral neuropathy
Hypothyroidism: What effect does hypothyroidism have on the central nervous system?
it causes lethargy
Hypothyroidism: What effect does Hypothyroidism have on reproduction? 3
infertility
prolonged anoestrus
testiscular atrophy
Hypothyroidism: What effect does Hypothyroidism have on the Gastrointestinal system?
- why? 3
constipation
it reduces appetite
it reduces the secretion of pancreatic enzymes
it reduces gut motility
Hypothyroidism: What effect does Hypothyroidism have on integument, specifically hair? 2
- Why? 2
alopecia
failure to regrow hair after clipping
thyroid hormone initiates and maintains anagen phase
so lack of thyroid maintains hair in telogen phase
Hypothyroidism: What other skin changes do you see with Hypothyroidism 5
bilateral symmetrical alopecia
lichenification
comedones
hyperpigmentation of alopecic sites
recurrent infections of the skin and ear
Hypothyroidism: Diagnosis
- What information gathering tests would you perform before specific hypothyroid tests?
blood biochemistry
complete blood count
Hypothyroidism: What would you expect to see on blood biochemistry?
- isn’t this counter intuitive?
increased parameters of lipid metabolism like cholesterol and lipids
yes but you get decreased activity of LDL receptors during hypothyroidism so have less catabolism of lipids
Hypothyroidism: What would you expect to see on a complete blood count? 2
normocytic normochromic anaemia
leukocytosis if there is an infection
