2.4.3 Parathyroid and Calcium Homeostasis Flashcards
And this one!
Post surgical hypoparathyroidism
Look at the following case and tell me what they have
Draw a graph showing the relationship of Ca2+ and PTH.
What cells release parathyroid hormone?
Parathyroid chief cells
How would you treat someone with hypoparathyroidism?
Calcium supplementation
Calcitriol - 1, 25 dihydroxy vitamin D
What is the mutation in familial hypoparathyroidism with hypercalcuria?
Activating mutation of the CSR
What are the characteristics of hypoparathyroidism?
Hypocalcemia
Inappropriately low PTH
What is primary hyperparathyroidism?
Elevated calcium with inappropriately normal or elevated PTH
What are the characteristics of primary hyperparathyroidism?
A vitamin D excess can lead to?
Hypercalcemia and Hypercalciuria
What does this patient have?
Low PTH
Elevated PTHrp
Breast CA dx
When chronically stimulated how will chief cells respond?
They will replicate
Look at the following case and tell me what is going on
Patient has high PTH
Low Urine calcium
It is FHH
How can sarcoidosis lead to kidney stones?
Sarcoid granuloma increases calcitriol which will increase Ca GI absorption
Increase serum Ca and increase excretion in the kidney
STONES!
What would FHH do to levels of Mg and urine calcium?
Mg - increased
Urince calcium - decreased
How does PTH act on the bone?
It acts directly on the bone to stimulate calcium reabsorption
A mutation in the Parathyroid Calcium-Sensing Receptor leading to?
Familial hypocalciuric hypercalcemia (FHH)
or
Familial hypoparathyroidism with hypercalciuria
What is the mechanism of action of calcitonin?
Decreases tubular reabsorption of calcium
Inhibits osteoclast mediated bone reabsorption
How would PTH respond to decreasing levels of 25 OHD?
PTH will rise to stimulate conversion of 25OHD to 1,25OH2D3
This will maintain intestinal absorption of calcium
32 y/o male with Chron’s disease ⇒ hypocalcemia related to malabsorption. Will PTH be increased or decreased?
Increased
How do you defend against bone loss?
Draw a schmatic on how PTH affects:
Bone
Kidneys
Intestine
What is calcitriol?
Hormonally active Vitamin D - will act to raise blood calcium levels
54 y/o female with breast cancer ⇒ hypercalcemia secondary to PTHrP. Will PTH be increased or decreased?
Decreased
What are some consequences of Vitamin D deficiency?
What does familial hypoparathyroidism with hypercalcuria do to PTH and urine calcium levels?
PTH - decreased
Urine calcium - increased
Look at this one too!
Low PTH
Elevated 1,25 (OH)2D3
CXR for lymphoma or sarcoidosis
What is the role of calcitriol on the synthesis of PTH?
Inhibits PTH synthesis by interacting with VDR
How quickly do levels of parathyroid hormone respond to changes in calcium?
Rapid secretion of PTH allows for quick response of PTH to changing levels
How would FHH effect levels of PTH and calcium?
Increase PTH
Increase Calcium
This one!
What is the mutation in FHH?
Inactivating mutation of the CSR
How does PTH act on the kidney in regards to phosphate?
Calcitonin is secreted by?
C cells
Where is calcitonin produced?
Within C cells of the thyroid gland
What does familial hypoparathyroidism with hypercalcuria do to levels of serum calcium?
Decrease
How does PTH respond to hyperphosphatemia?
Increases
How would you treat a patient with Primary Hyperparathyroidism?
Surgery
or
Cinacalcet - increases chief cell CSR sensitivity to calcium - decreasing PTH
Following a parathyroidectomy she developed hypocalcemia on Post-OP day 1. Labs Revealed:
This is hungry bone syndrome
What is the role of PTH on Vitamin D?
PTH stimulates renal synthesis of 1,25 dihydroxyvitamin D which is a hormone that stimulates GI calcium reabsorption (making calcitriol)
