Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

REGUB > L10: Calcium Metabolism and Disorders of Calcium Balance > Flashcards

L10: Calcium Metabolism and Disorders of Calcium Balance Flashcards

1
Q

What are the 3 main organ systems involved in calcium homeostasis?

A
  1. GIT
  2. Kidneys
  3. Bones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Calcium can be absorbed from the GIT, but it requires something for this to occur - what is it?

A

activated vitamin D (calcitriol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the main calcium reservoir in the body? How is calcium exist in this reservoir?

A

reservoir: bone

- exists as hydroxyapatite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is bone resorption?

A

bone broken down - Ca2+ released into blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What type of Ca2+ can be filtered by the glomeruli in the kidneys?

A

ionized (free) calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where in the kidney nephron is Ca2+ reabsorbed the most? Which area of reabsorption has an effect on calcium regulation + dysregulation?

A

70% Ca2+ reabsorbed passively in proximal tubule

15% Ca2+ reabsorbed actively in distal nephron – hasa an effect on regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Most of Ca2+ is ionized (free/unbound), but there is some Ca2+ which is bound to something to circulate in the blood. What is it bound to?

A

Albumin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 2 main hormonal mediators of calcium balance?

A
  1. Parathyroid Hormone

2. Calcitriol (Vitamin D)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What cells are PTH secreted from?

A

chief cells of parathyroid hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the net effect of PTH?

A
  • increase calcium

- decrease phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the effect of PTH in response to hypocalcaemia in the GIT

A
  • promotes calcitriol formation (in kidney)
  • via upregulation of 1-alpha-hydroxylase enzyme
  • calcitriol increases GIT absorption of Ca2+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the effect of PTH in response to hypocalcaemia in the BONES

A
  • increase in osteoclast number + activity

- increases bone resorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the effect of PTH in response to hypocalcaemia in the KIDNEY

A
  • increase in calcium reabsorption in distal nephron
  • also promotes increase in 1-alpha-hydroxylase enzyme
  • increases renal excretion of phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does PTH lead to a decrease in phosphate?

A

it increases renal excretion of phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of 1-alpha hydroxylase enzyme?

A

promotes formation of calcitriol in kidney

– increases GIT absorption of Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the net effect of calcitriol?

A
  • increase Ca2+

- increase phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the effect of CALCITRIOL in response to hypocalcaemia in the GIT

A
  • increase absorption of Ca2+

- via increasing expression of TRPV6 channels

18
Q

Describe the effect of CALCITRIOL in response to hypocalcaemia in the BONES

A
  • increases pyrophosphate levels (mineralization inhibitor)

- increase bone calcium release

19
Q

Describe the effect of CALCITRIOL in response to hypocalcaemia in the KIDNEY

A
  • increases expression of TRPV5 channels + Calbindin-D28k

- increases reabsorption of calcium in distal convoluted tubule + CD

20
Q

What is bone mineralization?

A

the formation + growth of bone (structure)

21
Q

What is the catch phrase for the clinical manifestations of hypercalcaemia?

A

“Stones, bones, groans and pyschiatric overtones”

22
Q

What are the clinical manifestations of hypercalcaemia?

A
  • kidney stones
  • bone pain + weakness
  • abdominal pain + constipation
  • depression, confusion, lethargy
  • shorted QT interval on ECG
  • dehydration
23
Q

What is a common finding of hypercalcaemia on an ECG?

A

shortened QT interval

24
Q

List the 5 main causes of hypercalcaemia

A
  1. PTH Excess
  2. Vitamin D Excess
  3. Increased Bone Resorption
  4. Increased Ca2+ Intake
  5. Thiazides
25
How can thiazides lead to hypercalcaemia?
increase Ca2+ reabsorption in the distal nephron
26
In an outpatient, what is the most common cause of hypercalcaemia?
Primary Hyperparathryoidism - fault in parathyroid glands - too much PTH produced
27
In an inpatient, what is the most common cause of hypercalcaemia?
malignancy + immobility
28
How can immobility cause hypercalcaemia?
immobility leads to decrease in bone mass - bone resorption occurs
29
To diagnose hypercalcaemia, if the PTH level is normal or elevated, what will the diagnosis be?
primary hyperparathyroidism
30
To diagnose hypercalcaemia, if the PTH level is low and the PTHrP is elevated, what will the diagnosis be?
malignancy
31
List the 5 possible treatment options for hypercalcaemia
1. 0.9% Saline 2. Frusemide 3. Bisphosphonates 4. Calcitonin 5. Steroids
32
Why may 0.9% saline be given to treat hypercalcaemia?
- hypercalcaemia causes dehydration | - this is used for aggressive rehydration
33
What is the MOA of frusemide? Why is it used to treat hypercalcaemia?
- loop diuretic | - inhibits calcium reabsorption in distal tubule
34
What is the MOA of bisphosphonates? What is it used to treat?
- treatment for hypercalcaemia | - inhibits osteoclast bone resorption
35
What is the management/treatment of primary hyperparathyroidism?
Parathyroidectomy
36
What are the clinical manifestations of hypocalcaemia?
- agitation - hyperreflexia - convulsions - hypertension - long QT interval - Trousseau's Sign* - Chvostek's Sign*
37
What is Trousseau's Sign? What is it indicative of?
- upon inflation of BP cuff, get characteristic flexion at wrist and at MCP joint - get extension of IP joints sign of hypocalcaemia
38
What is Chvostek's Sign? What is it indicative of?
- it is the twitching of the facial muscles in response to tapping over the area of the facial nerve - sign of hypocalcaemia
39
List the 4 main causes of hypocalcaemia
1. Hypoparathyroidism 2. Vitamin D Deficiency 3. Bone Uptake 4. Dietary Deficiency of Calcium
40
List the 4 possible treatment options for hypocalcaemia
1. Oral Calcium (calcium carbonate) 2. IV Calcium (for severe symptoms) 3. Vitamin D (calcitriol) 4. Magnesium
41
Why is magnesium given to treat hypocalcaemia?
- magnesium is required for the production and release of parathyroid hormone - PTH will increase plasma calcium

REGUB (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions