2.4.3 Parathyroid and Calcium Homeostasis

Question 1

And this one!

Answer 1

Post surgical hypoparathyroidism

Question 2

Look at the following case and tell me what they have

Answer 2

Question 3

Draw a graph showing the relationship of Ca2+ and PTH.

Answer 3

Question 4

What cells release parathyroid hormone?

Answer 4

Parathyroid chief cells

Question 5

How would you treat someone with hypoparathyroidism?

Answer 5

Calcium supplementation

Calcitriol - 1, 25 dihydroxy vitamin D

Question 6

What is the mutation in familial hypoparathyroidism with hypercalcuria?

Answer 6

Activating mutation of the CSR

Question 7

What are the characteristics of hypoparathyroidism?

Answer 7

Hypocalcemia

Inappropriately low PTH

Question 8

What is primary hyperparathyroidism?

Answer 8

Elevated calcium with inappropriately normal or elevated PTH

Question 9

What are the characteristics of primary hyperparathyroidism?

Answer 9

Question 10

A vitamin D excess can lead to?

Answer 10

Hypercalcemia and Hypercalciuria

Question 11

What does this patient have?

Answer 11

Low PTH

Elevated PTHrp

Breast CA dx

Question 12

When chronically stimulated how will chief cells respond?

Answer 12

They will replicate

Question 13

Look at the following case and tell me what is going on

Answer 13

Patient has high PTH

Low Urine calcium

It is FHH

Question 14

How can sarcoidosis lead to kidney stones?

Answer 14

Sarcoid granuloma increases calcitriol which will increase Ca GI absorption

Increase serum Ca and increase excretion in the kidney

STONES!

Question 15

What would FHH do to levels of Mg and urine calcium?

Answer 15

Mg - increased

Urince calcium - decreased

Question 16

How does PTH act on the bone?

Answer 16

It acts directly on the bone to stimulate calcium reabsorption

Question 17

A mutation in the Parathyroid Calcium-Sensing Receptor leading to?

Answer 17

Familial hypocalciuric hypercalcemia (FHH)

or

Familial hypoparathyroidism with hypercalciuria

Question 18

What is the mechanism of action of calcitonin?

Answer 18

Decreases tubular reabsorption of calcium

Inhibits osteoclast mediated bone reabsorption

Question 19

How would PTH respond to decreasing levels of 25 OHD?

Answer 19

PTH will rise to stimulate conversion of 25OHD to 1,25OH₂D₃

This will maintain intestinal absorption of calcium

Question 20

32 y/o male with Chron’s disease ⇒ hypocalcemia related to malabsorption. Will PTH be increased or decreased?

Answer 20

Increased

Question 21

How do you defend against bone loss?

Answer 21

Question 22

Draw a schmatic on how PTH affects:

Bone

Kidneys

Intestine

Answer 22

Question 23

What is calcitriol?

Answer 23

Hormonally active Vitamin D - will act to raise blood calcium levels

Question 24

54 y/o female with breast cancer ⇒ hypercalcemia secondary to PTHrP. Will PTH be increased or decreased?

Answer 24

Decreased

Question 25

What are some consequences of Vitamin D deficiency?

Answer 25

Question 26

What does familial hypoparathyroidism with hypercalcuria do to PTH and urine calcium levels?

Answer 26

PTH - decreased Urine calcium - increased

Question 27

Look at this one too!

Answer 27

Low PTH Elevated 1,25 (OH)2D3 CXR for lymphoma or **sarcoidosis**

Question 28

What is the role of calcitriol on the synthesis of PTH?

Answer 28

Inhibits PTH synthesis by interacting with VDR

Question 29

How quickly do levels of parathyroid hormone respond to changes in calcium?

Answer 29

Rapid secretion of PTH allows for quick response of PTH to changing levels

Question 30

How would FHH effect levels of PTH and calcium?

Answer 30

Increase PTH Increase Calcium

Question 31

This one!

Answer 31

Question 32

What is the mutation in FHH?

Answer 32

Inactivating mutation of the CSR

Question 33

How does PTH act on the kidney in regards to phosphate?

Answer 33

Question 34

Calcitonin is secreted by?

Answer 34

C cells

Question 35

Where is calcitonin produced?

Answer 35

Within C cells of the thyroid gland

Question 36

What does familial hypoparathyroidism with hypercalcuria do to levels of serum calcium?

Answer 36

Decrease

Question 37

How does PTH respond to hyperphosphatemia?

Answer 37

Increases

Question 38

How would you treat a patient with Primary Hyperparathyroidism?

Answer 38

Surgery or Cinacalcet - increases chief cell CSR sensitivity to calcium - decreasing PTH

Question 39

Following a parathyroidectomy she developed hypocalcemia on Post-OP day 1. Labs Revealed:

Answer 39

This is hungry bone syndrome

Question 40

What is the role of PTH on Vitamin D?

Answer 40

PTH stimulates renal synthesis of 1,25 dihydroxyvitamin D which is a hormone that stimulates GI calcium reabsorption **(making calcitriol)**