7. Parathyroid gland

Question 1

Hormones / vitamins related to the physiology of calcium and phosphate metabolism

Answer 1

1. parathyroid hormone (PTH)
2. Calcitonin
3. Vitamin D

Question 2

synthesized and stored in the chief cells of the parathyroid glands.

synthesis is regulated by a feedback mechanism involving the level of blood calcium

Answer 2

PTH

Question 3

function is to control calcium concentration in the extracellular fluid

by affecting the rate of transfer of calcium into and out of bone, resorption in the kidneys, and absorption from the GI tract.

Answer 3

PTH

Question 4

PTH

its effect on this organ is the most rapid
- reabsorption of calcium
- excretion of phosphorus

Answer 4

Kidney

Question 5

second major hormone for Ca metabolism and skeletal remodeling

must be metabolically activated before it can function physiologically

Answer 5

Vitamin D

Question 6

cholecalciferol (animal origin)

Answer 6

vitamin D3

Question 7

ergocalciferol (plant origin)

Answer 7

vitamin D2

Question 8

vitamin D is formed in the skin from this cholesterol metabolite, after exposure to ulraviolet light

Answer 8

7-dehydrocholesterol

Question 9

1,25-dihydroxyvitamin D

Answer 9

calcitriol

Question 10

hydroxylation of vitamin D in the liver to form this

Answer 10

calcitriol

Question 11

a 32-amino acid polypeptide hormone secreted by the parafollicular cells (C-cells)

Answer 11

Calcitonin

Question 12

interacts with target cells, primarily in bone & kidney

Answer 12

Calcitonin

Question 13

result of decreased entry of calcium from the skeleton into plasma, resulting from a temporary inhibition of PTH-stimulated bone resorption

Answer 13

hypocalcemic effects of Calcitonin

Question 14

impaired ability to concentrate urine and a direct stimulation of the thirst center

• polydipsia
• polyuria

Answer 14

hypercalcemia

Question 15

most common tumor associated with hypercalcemia

Answer 15

lymphoma (lymphosarcoma)

Question 16

Diagnosis of hypercalcemia

Answer 16

1. thoracic & abdominal radiographs
2. lymph node aspirates & biopsy
3. multiple bone marrow aspirate

Question 17

hypercalcemia tumor usually occuring in older dogs of either sex (90%)

• malignant
• metastasize to regional lymph nodes

Answer 17

adenocarcinoma of the apocrine gland (anal sac)

Question 18

reduction of serum calcium

Answer 18

surfical resection

Question 19

malignancy in dogs and cats (hypercalcemia) is 10-15%

multifactorial pathogensis, involving myeloma cells produciing osteoclast-activating factor

presence of extensive bony lysis contribute to increased serum calcium

Answer 19

multiple myeloma

Question 20

treatment of multiple myeloma

Answer 20

chemotherapy

Question 21

excessive secretion of PTH by one or more abnormal (usually neoplastic) parathyroid glands

rare in dogs & cats

Answer 21

primary hyperparathyroidism

Question 22

most common cause of primary hyperparathyroidism

Answer 22

solitary adenoma

Question 23

diagnosis of thisi involves finding multiple enlarged parathyroid gland

Answer 23

secondary hyperparathyroidism

Question 24

diagnostic alternative if no other cause of hypercalcemia can be determined

Answer 24

exploratory surgery

Question 25

disease that can also cause hypercalcemia (30% in dogs)

Answer 25

hypoadrenocorticism

Question 26

most common cause of hypercalcemia in CATS

Answer 26

renal failure

Question 27

syndrome affects young to middle-aged cats

excessive vitamin D content in cat food

Answer 27

idiopathic hypercalcemia (cats)

Question 28

plants that cause hypercalcemia

Answer 28

houseplants

Cestrum diurnum
Solanum malacoxylon
Trisetum flavescens

Question 29

hypercalcemia that arises from an alteration of endogenous vitamin D metabolism

Answer 29

granulomatous disease

Question 30

evaluates calcium abnormalities;

it evaluates whether parathyroid gland are responding appropriately to change in calcium concentration

Answer 30

assay of PTH

Question 31

very useful in evaluation of hypercalcemic dogs & cats

Answer 31

serum/plasma PTH

Question 32

production of a humoral factor, PTHrP, that has parathyroid hormone-like bioactivity

Answer 32

nonparathyroid neoplasia

Question 33

hypocalcemia
hypophosphatemia

either transient or permanent PTH insufficienty

Answer 33

HYPOparathyroidism