Endocrine 2, Thyroid & Parathyroid Flashcards
What hormones are released in which steps of the Hypothalamic pituitary axis?
- Hypothalamus (TRH)
- Hypophysis (TSH)
- Thyroid (T3 - T4)
What happens in the Liver and Kidney?
T4 is converted into T3 (50%) and some T4 is converted into T3r (reverse/inactive)
As for biological activity, which is more potent T3 or T4?
T3 is more potent than T4
What are some metabolic regulations that Thyroid hormones cause?
They’re involved in oxygen consumption, metabolism of proteins, carbohydrates, fats and vitamins.
- Thermoregulatory action
- increase oxygen consumption
- stimulate the synthesis and degradation of proteins
- Regulate mucoproteins and extracellular water
- Synthesis and degradation of fats
Name some more metabolic regulations of the Thyroid hormones?
- Glycogen synthesis and glucose utilization
- Formation of vitamin A from carotenes
- development of CNS and PNS
- Muscle contraction and intestinal motility
- growth and developed
What does it mean that the problem is Primary or Secondary?
The problem is:
Primary: Effector organ
Secondary: Hypothalamic/pituitary axis
What are some causes of primary hypothyroidism?
95% of the cases are primary.
- Lymphocytic thyroiditis (most common in dogs
- Idiopathic atrophy
- Tumors
- Iodine deficiency (rum and pigs)
What are some causes of secondary hypothyroidism?
Pituitary disorders (congenital, neoplasia, drug toxicity)
Would these symptoms be primary or secondary?
HIGH TSH
LOW T4
NORMAL T4
This is primary hypothyroidism! If the T4 is normal, then it’s subclinical.
Would these symptoms be primary or secondary?
NORMAL TSH
LOW T4
This is secondary hypothyroidism!
The pituitary gland is sending normal amount of TSH yet there’s low T4 which would have to mean the problem is secondary.
Clinical signs from hypothyroidism?
Essentially the Basal Metabolism Rate is decreased!
- Weakness, exercise intolerance
- Sleepy
- Hypothermia
- Weight gain
Progressive onset of signs – not easy to diagnose.
So everything goes down!
Skin disorders from hypothyroidism?
- Alopecia (absence of hair. Bilateral, generalized, non pruritic, “rat tail”)
- Dull hair, slow growth
- Hyperpigmentation, hyperkeratosis
- tendency to infections (pyoderma, pruritus)
Reproductive disorders from hypothyroidism?
Female:
- Prolonged oestrus cycle
- Silent oestrus
Males:
- Testicular atrophy
- Lack of libidio
- Azoospermia
Both increase TRH
- Gynecomastia (enlarged mammary glands)
- Galactorrhea (excessive milk production)
Neuromuscular disorders?
Glycosaminoglycan deposits in nerve fibers. Axonal demyelination.
- Paralysis/paresis peripheral nerves
- Laryngeal paralysis (aphony)
Meaning, the cartilage doesn’t work properly in larynx.
Any other less frequent disorders?
Cardiac disorder
- Bradycardia, weak pulse, arrhythmias.
Ocular disorders
- Lipid deposit in cornea (white cornea might be the only sign owners might see)
