Calcitonin/PTH/VitD

Question 1

What is the site of synthesis for calcitonin? (cell type/gland)

Answer 1

Parafollicular cells AKA “C” cells in thyroid gland

Question 2

What is the chemical class of calcitonin?

Answer 2

PPP (polypeptide)

Question 3

What are the 3 primary functions of calcitonin?

Answer 3

• Decrease plasma calcium
• Decrease osteoclast cell synthesis and activity***
• Decrease 1 hydroxylase enzyme activity

Question 4

What is the secondary function of calcitonin?

Answer 4

decrease pain*

Question 5

Calcitonin has what affect on calcium and phosphate in plasma? How does it affect bone reabsorption?

Answer 5

• LOWERS calcium/phosphate in plasma*

- INHIBITS bone reabsorption***

Question 6

Calcitonin can be an effective treatment to people who suffer from what condition and have had adverse reactions to bisphosphonates?

Answer 6

Osteoporosis** (Calcitonin can prevent fractures from osteoporosis)

Question 7

What bone condition associated with calcitonin issues is characterized as a disorder of the normal bone remodeling or bone that is formed is abnormal, enlarged and weak?

Answer 7

Osteitis/Paget’s disease* (MC in 50+ year olds)

Question 8

What is the site of synthesis for PTH? (cell type/gland)

Answer 8

Dark Chief Cells – Parathyroid gland*

Question 9

What is the chemical class for PTH?

Answer 9

PPP - Preprohormone

Question 10

A deficiency of PTH can lead to what condition?

Answer 10

Hypocalcemia (decreased calcium in blood)

- causes Tetany

Question 11

What are the 3 primary functions of PTH?

Answer 11

Stimulate growth*
Increase 100% Vit. D synthesis**
Increase plasma calcium*

Question 12

What is the most powerful hormone to increase plasma calcium? What is it regulated by?

Answer 12

PTH

- Regulated by cAMP

Question 13

What are the secondary functions of PTH? (the big 4)

Answer 13

Increase metabolism
Increase plasma glucose
Increase blood pressure
Increase immune response

Question 14

What is the site of synthesis for vitamin D?

Answer 14

Liver =  25-(OH) D3*
Kidney = All 100% forms - active*

Question 15

What is the chemical class of vitamin D?

Answer 15

Seco-steroid*

Question 16

What 3 parts of the body are involved in vitamin D synthesis?

Answer 16

skin, liver, kidney

Question 17

Irradiation of what substance in skin by ultraviolet rays makes Cholecalciferol (D3)?

Answer 17

7-dehydrocholesterol

Question 18

Cholecalciferol (D3) in skin is converted to what substance in the liver?

Answer 18

25-hydroxycholecalciferol

Question 19

25-hydroxycholecalciferol is converted to 1,25-Dihydroxycholecalciferol in the proximal tubules of the kidneys under the control of what hormone?

Answer 19

PTH

Question 20

Vitamin D is ______ regulated when first synthesizing in the kidney, then ______ regulated by the activity of what substance in the kidney?

Answer 20

loosely, tightly, 1-alpha-hydroxylase

Question 21

What hormone has major control of 1-alpha-hydroxylase?

Answer 21

PTH

Question 22

What are the 2 primary functions of vitamin D?

Answer 22

• Increase linear height**

- Increase plasma calcium*

Question 23

What is the secondary function of vitamin D?

Answer 23

Stimulate integumentary system (skin and hair)*

- Alopecia can occur (hair loss)

Question 24

What are the 3 things that can affect vitamin D synthesis?

Answer 24

• plasma calcium levels
• sunlight
• hormones (PTH/glucagon/cortisol)

Question 25

What are the 2 major causes of vitamin D deficiency?

Answer 25

- Sun shunning*

- Strict vegetarian diet (most animal based foods = vitamin D)

Question 26

What are some conditions associated with vitamin D deficiency?

Answer 26

• Rickets
• Increase risk of cardiovascular disease*
• Cognitive impairment*
• Severe asthma in children*
• Some cancers*