Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Met 3b > Calcium Disorders > Flashcards

Calcium Disorders Flashcards

1
Q

Calcium function

A

Bone mineralization
Blood clotting
Muscle contraction
Nerve function + neurotransmission

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

Serum calcium levels

A

2.2-2.6 mmol/L

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

Calcium state

A

Most serum calcium bound to plasma proteins (mainly albumin)
Only unbound calcium is biologically active
Serum calcium always needs to be corrected for albumin concentration

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

Serum calcium + albumin conc

A

+/- 0.02 mmol/L for every gram that albumin is below/above 40g/dL

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

Calcium hormonal regulation

A

Vitamin D
Parathyroid hormone
(calcitonin)

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

Vitamin D conversion

A

Vitamin D3 (cholecalciferol) - synthesizes in sun-exposed epidermis
Requires 2 activation (hydroxylation) steps
Liver- 25 hydroxycholecalciferol (majority Vit D in this form)
Kidney- 1,25-dihydroxycholecalciferol (calcitriol)

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

Majority of Vit D is in this form

A

25-hydroxycholecalciferol

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

Vit D bound

A

25-dihydroxycholecalciferol mostly bound to plasma proteins

1,25-dihydroxycholecalciferol largely unbound

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

1,25-dihydroxycholecalciferol half life

A

Short

15 hours

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

Calcitriol binds to

A

Nuclear vitamin D receptors

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

Vit D in Gut

A

Vit D increases the absorption of dietary calcium and phosphate

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

Vit D in kidney

A

Increases calcium and phosphate reabsorption

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

Vit D in bone

A

Stimulates osteoclasts to release calcium and phosphate

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

Parathyroid gland

A

4 parathyroid glands

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

PTH

A

Secreted by chief cells within parathyroid gland
Released in response to low calcium levels
Can also be stimulated by changes in phosphate concentration
Acts to increase serum Ca

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

PTH on Kidney

A

Increases Vit D
Increases Ca and Hydrogen reabsorption
Decreases phosphate and bicarbonate reabsorption

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

PTH on bone

A

Inhibits osteoblasts

Stimulates osteoclasts

18
Q

Parathyroid-related peptide (PTHrP)

A

Acts via same cell surface receptor as PTH

Synthesised by placenta + breast, where it contributes to 1 alpha hydroxylation

19
Q

Calcitonin

A

Secreted by parafollicular C cells of thyroid
In response to raised serum calcium
Acts on renal tubules to reduce calcium and phosphate reabsorption
Inhibits osteoclasts

20
Q

Hypocalcaemia signs and symptoms

A

Muscle cramps
Trousseau’s sign- carpopedal spasm when applying BP cuff
Tetany and neuromuscular excitability
Chvostek’s sign- tapping over the facial nerve causes facial muscles to twitch
Mood swings
Convulsions
Cardiac arrhythmias

21
Q

Hypocalcaemia causes- hypoparathyroidism

A

Surgical removal (thyroidectomy)
Autoimmune damage
Congenital (De George Syndrome agenesis of the parathyroid)

22
Q

Hypocalcaemia causes- not hypoparathyroidism

A 
Hypomagnesaemia
Renal failure (PTH can no longer increase Vit D hydroxylation, and hypocalcaemia can develop)
PTH resistance (aka pseudohypoparathyroidism)
23
Q

Hypocalcaemia treatment

A

Oral calcium

Calcitriol

24
Q

Hypercalcaemia signs and symptoms

A 
Tiredness + fatigue
Anorexia + nausea
Thirst + polyuria
Muscle weakness
Headache
Body pain
Renal stones
Abdo pain (constipation, pancreatitis)
Mood disturbance 
Cardiac arrhythmias
25
Q

Hypercalcaemia causes

A 
Primary hyperparathyroidism
Malignancy
Drugs and diet
Familial benign hypercalcaemia
Granulomatous disease- Sarcoidosis
Tertiary hyperparathyroidism
26
Q

Primary hyperparathyroidism

A

Relatively common
80% single parathyroid adenoma (remainder hypertrophy of more than one gland)
Parathyroid malignancy rare

27
Q

If parathyroid malignancy found in patients <45, consider..

A

MEN syndrome

28
Q

Hypercalcaemia- malignancy that secretes PTHrP

A

Classically squamous lung cell cancer

29
Q

Hypercalcaemia- malignancy

A

Malignancy that secretes PTHrP
Bone metastases
Multiple myeloma- sclerotic bone lesions

30
Q

Hypercalcaemia- secondary hyperparathyroidism

A

Usually in renal failure context
Lack activation of Vit D, with hypocalcaemia, as well as increased phosphate levels stimulate the parathyroid gland to increase production to compensate

31
Q

Hypercalcaemia- tertiary hyperparathyroidism

A

With prolonged secretion of parathyroid hormone, the glands may become autonomous
Over secrete PTH even when calcium levels have normalised

32
Q

Hypercalcaemia causes- drugs and diets

A

Thiazide diuretics - increased calcium reabsorption from distal tubule
Vit D overdose

33
Q

Hypercalcamia Causes- familial benign hypercalcaemia

A 
AKA familial hypocalciuric hypercalcaemia (FHH)
Autosomal dominant
Defective calcium receptor on PT gland
Leads to reduce negative feedback
--> elevated PTH and calcium
Elevated PTH causes hypocalciuria
FHH doesn't need treatment
34
Q

Hypercalcamia causes- sarcoid and GH

A

Non-caseating granulomas can have 1 alpha hydroxylase activity
GH can also stimulate renal alpha 1 hydroxylase activity

35
Q

Hypercalcaemia investigations

A

Serum Ca and phosphate
PTH- primary, tertiary or FHH: high or inappropriately “normal” in context of elevated calcium
Vit D (PTH raised in Vit D deficiency)
24 hr urinary Ca collection

36
Q

Hypercalcaemia investigations- primary hyperparathyroidism

A

Imaging of parathyroid- CT or MRI, isotope uptake scan

Venous sampling

37
Q

Hypercalcaemia investigations- other

A

Look for malignancy- XR chest, CT
Urinary Bence Jones proteins
Serum ACE

38
Q

Hypercalcaemia treatment- Severe

A

EMERGENCY
IV rehydration
IV biphosphonates (e.g. pamidronate)
Steroids in haematological malignancy or sarcoidosis

39
Q

Hypercalcaemia treatment- mild

A

Can monitor as rarely worsens

40
Q

Hypercalcaemia- surgery

A

Considered when complications:
Renal impairment
Stones
Bone demineralisation

Met 3b (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions