Endocrinology Flashcards
Endocrinology
Glands produce chemical messengers (hormones)
Hormones produced in one part of the body and travel to target organs via bloodstream
Positive feedback loops
Oxytocin @ parturition
Prolactin @ lactation
Negative feedback loops
Thyroid hormone
Progesterone
Estrogen
Cortisol
Significance of feedback loops
Help the body respond to changes in the body
Understand testing for endocrine diseases
Understand medications to treat endocrine diseases
Thyroid
Hypothalamus —> TRH —> pituitary —> TSH —> Thyroid glands —> T3 and T4 in the blood
What body systems does the thyroid affect?
HR
Temperature
Use of calories
Speed food moves through body
Managing skin cell replacement
What CS would you see in an animal with hyperthyroidism?
↑ HR, body temp and metabolism
Skin cell turnover (flaky, not groomed well)
Polyphasic, WL, vomiting
What can cause hyperthyroidism
Benign neoplasia
Hyperplasia (70% both lobes)
Dx testing for hyperthyroidism diseases
PE (palpate thyroid slip)
Routine blood work (CBC, chemistry, urinalysis)
Endocrine testing (total T4, free T4 by dialysis, TSH)
ECG (murmur with thickened heart wall)
Technetium scan
How is TSH produced in hyperthyroidism?
↓ because the body doesn’t need anymore produced (negative feedback)
CS of a dog with hypothyroidism
Lethargy and weight gain (slow metabolism)
Dull skin (with infections)
Bradycardia
Hypothermia
Causes of hypothyroidism
Lymphocytic infiltration of thyroid
Atrophy of thyroid
Congenital (rare)
Iatrogenic (cats)
Dx testing for hypothyroidism
PE
Routine bloodwork (CBC, chemistry, urinalysis)
Endocrine testing (total T4, free T4 by dialysis and ↑ TSH)
Tx if hyperthyroidism
Radioiondine treatment (lowers T levels with radioactive iodine)
Change diet
Methimazole
Sx
Tx of hypothyroidism
Supplementation: thyroxine (giving thyroid hormones daily)
Glucocorticoids action
Promotes gluconeogenesis
Suppresses immune response
Inhibits inflammatory response
↑ lipolysis, proteolysis and GFR
Mineralcorticoids actions
↑ sodium reabsorption, potassium and hydrogen secretion
Dx testing for hyperadrenocorticism (Cushings)
PE (high BP, pot belly, thin skin)
Routine bloodwork (CBC, chemistry (high ALT and ALP)
Urinalysis (proteinuria)
Endocrine test (for hyperadrenocorticism)
Screening test:
ACTH stimulation testing, urine cortisol creatinine, low dose dexamthasone suppression
Differentiation between pituitary and adrenal hyperadrenocorticism
High dose dexmathasone suppression
Endogenous ACTH
Ultrasound (pituitary: both glands enlarged, adrenal: one gland enlarged)
Tx of hyperadrenocorticism
Trilostane (enzyme inhibitor)
Lysodren (destroys adrenal cells)
Monitor with ACTH stimulation test
Common CS for hypoadrenocorticism (addisons)
Lethargy, collapse and watery diarrhea
but could present for anything
Dx testing for hypoadrenocorticism
PE
Routine bloodwork (CBC, lack of stress leukogram)
Chemistry (hyponatremia, hyperkalemia)
Urinalysis
Endocrine testing for hypoadrenocorticism
Basal cortisol: <2 mcg/dl = additional testing needed —> ACTH stimulation test
