Calcium Phosphate Homeostasis Dr. LH

Question 1

What is embryonic derivative of adrenal medulla and what does it secrete?

Answer 1

Neuro ectoderm and secretes catecholamines

Question 2

Patient has high PTH levels, high calcium, and high vitamin D. Pi is low. What is causing these values?

Answer 2

Primary hyperparathyroidism

Question 3

Describe primary hyperparathyroidism

Answer 3

• High PTH
• High Ca
• High Vit D
• Low Pi

Question 4

Describe PTH Ca Pi and VitD in renal failure.

Answer 4

• High PTH
• Low Ca bc not reabsorbing from kidney
• High Pi bc not excreting
• Low Vit D bc can’t activate 1a-Hydroxylase

Question 5

Hypoparathyroidism values?

Answer 5

• Low PTH
• Low Ca
• High Pi
• Low Vit D

Question 6

Patient presents to her post op check up after her thyroid surgery with complaints of numbness and tingling around her mouth and fingers as well as muscle cramps. What is going on?

Answer 6

Hypoparathyroidism

Question 7

Causes of secondary hyperparathyroidism?

Answer 7

Renal failure of Vitamin D deficiency

Question 8

Values with vitamin D deficiency?

Answer 8

• High PTH
• Low Ca
• Low Pi
• Low Vit D

Secondary Hyperparathyroidism

Question 9

Estradiol 17B effects on calcium?

Answer 9

• Stimulates Intestinal Ca absorption and Renal tubular ca reabsorption
• Potent regulator of osteoblast and clasts
  
  • Promotes bone formation

Question 10

Stones bones and groans? Hypercalciuria stones, increase bone resorption and constipation, what is happening?

Answer 10

Primary hyperparathyroidism

Question 11

What is Albright hereditary osteodystrophy (Psuedohypoparathyroidism type 1a)?

Answer 11

• Autosomal Dominant Gs for PTH in bones and kidneys is defective
• Hypocalcemia and Hyperphosphatemia develop
• High levels of PTH due to resistance

Question 12

A short woman with obesity and noticably shortened fingers and necks comes into the clinic complaining of muscle spasms. You suspect ______( Hypoparathyroidism, Psuedohypoparathyroidism, Hyperparathyroidism). You get labs to check, what should you see?

Answer 12

Psuedohypoparathyroidism (Albrights)

• High PTH levels due to resistance
• Low Ca levels due to bone and kidney not reabsorbing
• High Pi
• Low VitD

Question 13

Describe Humoral Hypercalcemia of Malignancy.

Answer 13

PTHrP is produced by tumors and its very similar to PTH as it binds and activates Type 1 PTH receptor

• High PTH-rP which leads to
  
  • High Urinary Ca, High urinary Pi, High urinary cAMP
  • High blood Ca, Low blood Pi
• Low PTH levels bc PTH-rP gives neg.FB
• Low Vit D bc doesn’t activate 1a-hyrdoxylase

Question 14

What causes FHH?

Answer 14

Mutations inactivating CaSR in parathyroid goloands and parallel Ca receptors in ascending limb of kidney

Question 15

FHH lab levels? general high or low

Answer 15

• PTH is normal or high
• Serum Ca is high
• Urine Ca is low
• Pi is normal
• Vitamin D is normal

Question 16

What effect does high calcium and separately PTH stimulation have on 1a-Hydroxylase?

Answer 16

Ca:

• Decreases transcription of CYP1a gene which leads to 1a-hydroxylase, you don’t need more calcium reabsorption

PTH:

• Decreased Ca levels increases PTH which activates CYP1a to make 1a-hyrdoxylase to make Vitamin D

Question 17

Chronic Hypercalcemia effect on PTH?

Answer 17

Causes decrease synthesis and storage of PTH and increased breakdown of stored PTH and release of inactive PTH fragments into circulation

Question 18

Chronic Hypocalcemia effect on PTH?

Answer 18

• Causes increase synthesis and sstorage of PTH and hyperplasia of parathyroid glands (secondary hyperparathyroidism)