Thyroid and Parathyroid glands

Question 1

where the thyroid and parathyroid is located

Answer 1

thyroid: paried lobes on larynx
parathyroids: 4 (usually) on thyroid

Question 2

difference between T3 and T4 produced by thyroid

Answer 2

T3- more active form, made in smaller amounts

T4- converted to T3 in tissues

Question 3

what controls the secretion of T3 and T4 from the thyroid

Answer 3

TSH (thyroid stimulating hormone) from the pituitary gland

Question 4

what T3 and T4 thyroid hormones are used for in body

Answer 4

stimulates O2 consumption in cells, regulates fat and carb metabolism, needed for cell growth and maturation, increase nutrient absoption in GI tract

Question 5

what causes hyperthyroidism

Answer 5

thyroid tumor secreting excessive hormones

Question 6

signs of hypertyroidism

Answer 6

older cat, hyperactive, weight loss, polyphagia, increased HR, greasy hair coat, alopecia

Question 7

possible causes of hypothyroidism

Answer 7

lack thyroid hormones (primary): thyroiditis, idopathic atrophy
lack TSH from pituitary (secondary): pituitary tumor
lack iodine (dietary) produces goiter

Question 8

signs of hypothyroidism

Answer 8

lethargy, overweight, cold intolerant, dermatitis, alopecia, “tragic expression”

Question 9

resting T4 tests for

Answer 9

hyperthyroidism, not hypo- many other factors decrease T4 levels

Question 10

factors besides hypothyroidism that may decrease resting T4 levels

Answer 10

lower w age, certain illnesses, meds (phenobarbital or steroids), certain breeds (german shepards, labs, cockerspaniels, beagles, giant breeds)

Question 11

what TSh response tests for and how it is done

Answer 11

hypothyroid and differenciate between primary and secondary

take baseline sample (resting T4), inject TSH, take second sample 6 hrs later

Question 12

TSH response testing in normal animal, primary hypothyroidism, and secondary hypothyroidism

Answer 12

norm- T4 doubles
primary hypo- no change, both low (lack thyroid hormones)
secondary hypo- 2nd sample extremely elevated (we replace TSH that isnt being made by pituitary)

Question 13

why we may see lipemia in a fasted blood sample of a hypothyroid animal, and high cholesterol

Answer 13

thyroid hormones needed to regulate fat and carb metabolism

Question 14

_____in thryoid secretes hormones, _____ in thyroid stores them

Answer 14

parafollicular cells secrete, follicles store

Question 15

what calcium is needed for in body

Answer 15

w/ Ph for bone and teeth, muscle contractions, blood coagulation, nerve impulse transmission, enzymes systems

Question 16

what Ph is needes for in body

Answer 16

w/ calcium for bone and teeth, nucleic acids, cell metabolism

Question 17

2 hormones responsible for balance of Ca:P ratio and how they work, and where they are made

Answer 17

Calcitonin- produced by thyroid C-cells/ intrafollicular cells; decreases blood calcium, stores in bone

Parathormone- from parathyroid chief cells, increases blood calcium

Question 18

where parathormone acts on to increase blood calcium

Answer 18

breaks down bone, acts on kidneys so more Ca will be absorbed and more Ph excreted, acts on intestine receptors so more Ca will be absorbed

Question 19

diseases that affect Ca:Ph ratio (primary and secondary)

Answer 19

hyperparathyroidism: increases blood Ca
primary: parathyroid tumor (rare)
secondary: something exerting action on parathyroid- kidney disease (Ca excreted, PT hormone increases), nutritional, pseudohyperparathyroidism

Question 20

most common reason for Ca:Ph ratio imbalance

Answer 20

nutritional secondary hyperparathyroidism

Question 21

causes of nutritional secondary hyperparathyroidism

Answer 21

dietary Ca too low, dietary Ph too high, inadequate vitamin D

Question 22

how vitamin D is made from UVB light

Answer 22

inactive form cholecalciferol is made, actived in liver

Question 23

signs of nutritional secondary hyperparathyroidism

Answer 23

thin bones, fracture easily (osteoporosis), loose teeth, can cause ricketts in young

Question 24

what causes rickets in young

Answer 24

insufficient vitamin D or Ca

Question 25

pseudohyperparathroidism is also called

Answer 25

hypercalcemia of malignancy

Question 26

what is pseudohyperparathroidism

Answer 26

tumor (mammary, lymphosarcoma, or perianal) produces PTH- like substance (parathyroid hormone), Ca pulled from bones, see mineralization/calcium deposits in soft tissue (kidney, liver, heart)

Question 27

an inactive parathyroid is associated w what in diary cattle around parturition

Answer 27

milk fever/ parturient paresis

Question 28

sample we use to test Ca:ph levels

Answer 28

serum or heparinized plasma (not EDTA or oxylate bc contain Ca)