Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MEH > 13 Calcium Metabolism + parathyroid gland > Flashcards

13 Calcium Metabolism + parathyroid gland Flashcards

(58 cards)

Start Studying
1
Q

What is calcium vital for?

A
  • Nerve and muscle function - neuromuscular junction
  • Bone formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Three organs important in calcium metabolism

A

Bone
Kidney
Gut

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

Where is the parathyroid gland?

A

Behind the thyroid
Completely different to thyroid gland
4 of them

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

Relationship between main organs and calcium.

A

Gut - vitamin D activation absorption
Bone- resorption
Kidney- retention

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

Explain the role of PTH in regulating serum calcium levels

A
  • Increase bone resorption + Ca release into circulation
  • Increase kidney Ca retention + excretion of phosphate
  • Stimulation to make active vitamin D - calcitriol > indirectly acts on GI tract
  • decreases plasma phosphate
  • increases plasma calcium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does calcium cause in relation to phosphate?

A

Phosphate loss

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

What is needed to vitamin D synthesis?

A

Sunlight
Present in diet too

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

Vitamin D synthesis

A

Vitamin D3 + sunlight
25-hydroxylation
1-hydroxylation
Active form of vitamin D (calcitriol)

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

Where do you get vitamin D2 and D3 from?

A

D2 - mushrooms
D3 - oily fish e.g. salmon

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

Action of vitamin D

A
  • Kidney - increased Ca reabsorption
  • Parathyroid- decreased PTH production + parathyroid growth
  • Bone- promotes formation and growth
  • Gut - increased absorption of Ca2+ and PO4 3-
  • increases plasma calcium and phosphate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Outline the negative feedback regulation of serum calcium when there is an increase in plasma calcium

A

Decreased PTH secretion
Less calcitriol made
Less Ca2+ reabsorption in kidneys
Less bone breakdown, more bone building
Less Ca2+ absorbed in gut
Plasma Ca2+ levels decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Outline the negative feedback regulation of serum calcium levels when plasma calcium decreases

A

Increased PTH secretion
More calcitriol made
More Ca2+ reabsorption in kidneys
More bone breakdown, less bone building
More Ca2+ absorbed in gut
Plasma Ca2+ levels increases

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

What is hypercalcaemia?

A

High calcium
>2.51mmol/L
>3mmol/L severe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

features of hypercalcaemia

A
  • Polydipsia
  • Moans - tried, depressed
  • Groans - constipation, pancreatitis
  • Stones - kidney stones, polyuria
  • Bones - bone and muscle aches
  • corneal calcification
  • shortened QT interval
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Causes of hypercalcaemia

A
  • primary hyperparathyroidism (most common in non hospitalised patients)
  • malignancy (most common in hospitalised patients)
  • sarcoidosis
  • acromegaly
  • TB
  • Addison’s disease
  • thiazides
  • thyrotoxicosis
  • vitamin D intoxication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explanation of high Ca and low PTH

A

High calcium form somewhere else
Most likely cancer
Cancer produced PTH-like peptide

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

Cancers with high calcium

A
  • Myeloma-cancer of blood cells
  • Bone metastases -typical tumours that go to the bone: bronchus, thyroid, breast, kidney
  • SCLC PTHrP release

NOT prostate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Causes of high Ca, low PTH that’s not cancer

A

Tuberculosis
Sarcoidosis
Granulomas
Produce vit D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Treatment of hypercalcaemia

A
  • IV 0.9% saline 3-4 litres a day
  • Bisphosphonates after rehydration
  • IM or SC calcitonin if due to malignancy
  • steroids if due to sarcoidosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Types of hyperparathyroidism

A
  • primary: due to uncontrolled PTH productive by parathyroid tumor > hypercalcaemia
  • secondary: insufficient vitamin D or CKD > hypocalcaemia > more PTH produced in response to
  • tertiary: when secondary continue for an extended period of time > hyperplasia of parathyroid gland > PTH production remains high I
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Effects of primary hyperparathyroidism

A

Causes hypercalcaemia:
Moans - tried, depressed
Groans - constipation, pancreatitis
Stones - kidney stones, polyuria
Bones - bone and muscle aches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Blood findings of hyperparathyroidism

A
  • raised calcium
  • low phophate
  • PTH raised or normal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Treatment of primary hyperparathyroidism

A
  • total parathyroidectomy
  • cinacalcet - calcium mimetic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Symptoms of hypocalcaemia

Study These Flashcards
A

Numbness
Muscle twitching
Palpitations
Seizures
Severe symptoms if sudden drop

25
Signs of hypocalcaemia
Convulsions Prolonged Q-T interval on ECG Hyperreflexia- over responsive reflexes Trousseau’s sign Chvostek’s sign Swelling of optic disk
26
What is trousseau’s sign?
Involuntary contraction of muscle in hand and wrist
27
What is chvotek’s sign?
Contraction of ipsilateral face muscles after percussion over facial nerve
28
Causes of hypocalcaemia
- Vitamin D deficiency (osteomalacia) - Hypoparathyroidism *e.g. post thyroid/parathyroid surgery* - CKD - Acute pancreatitis - Massive blood transfusion
29
Treatment of hypocalcaemia
- IV calcium gluconate 10ml of 10% solution over 10 mins - ECG monitoring - treat underlying cause
30
Biochemistry of vitamin D deficiency
Low vit D Low Ca High PTH Low phosphate
31
Causes of vitamin D deficiency
Lack of sunlight Pigmented or covered skin Dietary deficiency GI disease Kidney disease
32
What can severe vitamin D deficiency cause?
Rickets in children Osteomalacia in adults
33
What is osteomalacia/rickets?
Demineralisation of bones Soft and weak bones Bend and break more easily Bowed kegs
34
Biochemistry of hypoparathyroidism
Low Ca Low PTH levels High phosphate
35
Causes of hypoparathyroidism
Surgical damage or removal Pathology of parathyroid gland Failure of 3rd or 4th branchial arch Look for scar in neck from surgery
36
What is needed in acute severe hypocalcaemia?
Medical emergency Assess airway and conscious level ECG monitor to check heart Intravenous calcium and monitor
37
What is osteoporosis?
Demineralised bone Brittle, fragile bones Break easily Looks like an areo bar
38
Risk factors for osteoporosis
- Post menopausal women - Family history - Smoking - Immobility - Endocrine diseases- hyperparathyroidism, hyperthyroidism, low testosterone in men, premature ovarian failure
39
Classic places for osteoporotic fractures
Vertebra Hip Wrist
40
Symptoms of osteoporosis
No symptoms Not painful until break
41
How is calcium transported in the blood?
Free ionised Ca2+ Bound to plasma protein Complexed with citrate
42
Explain the role of calcitonin in regulating serum calcium levels
- Released from thyroid gland from parafollicular cells - Opposes PTH action - Decreases plasma calcium levels
43
What cells are found in the parathyroid gland?
Chief cells - synthesis PTH Oxyphil cells
44
How does calcium regulate PTH synthesis?
Low serum calcium up-regulates gene transcription of PTH High serum calcium down-regulates gene transcription of PTH
45
Outline the action of PTH on the bone
1- PTH induces **osteoblasts to secrete cytokines** 2- cytokines stimulate differentiation + **activity of osteoclasts** 3- PTH **decreases osteoblast activity** 4- **reabsorption of mineralised bone** > **releases Pi and Ca2+**
46
How is vitamin D3 transported?
Found to transcalciferin
47
What is the half life of calcitriol
6hours
48
How much calcium is present in the adult human body in kg?
1kg
49
How do parathyroid glands sense plasma calcium conc.
By GPCR that are activated by calcium
50
Storage of calcium
In bones as hydroxyapatite crystals
51
What hormones are involved in calcium regulation?
Parathyroid hormone Calcitriol Calcitonin
52
What is released if calcium levels are high vs low?
- **high**: calcitonin to decreased plasma [Ca2+] - **low**: PTH to increased plasma [Ca2+]
53
Action of calcitriol on serum calcium
Raises calcium levels where there has been prolonged reduction
54
What is pseudo hypoparathyroidism
Target cells are insensitive to PTH > hypocalcaemia, high phosphate + high PTH
55
Causes of hypophosphataemia
- alcohol excess - primary hyperparathyrodism - DKA - refeeding syndrome - osteomalacia
56
complications of hypophosphataemia
- RBC haemolysis - WBC + platelet dysfunction - muscle weakness + rhabdomyolysis - central nervous system dysfunction
57
ECG change in hypercalcaemia
Shortened QT interval
58
ECG change in hypocalcaemia
Prolonged QTc

MEH (23 decks)

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