Calcium Homeostasis and Disorders Flashcards Preview

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Flashcards in Calcium Homeostasis and Disorders Deck (36):
1

What is the recommended daily dose of calcium?

700mg

2

What 4 factors contribute to Calcium homeostasis?

Diet
Gut absorption
PTH
Vit D

3

Briefly explain the pathway that leads to increased serum calcium.

Ca --> Calcium sensing receptor (CaSR) --> PTH --> resorption of Ca from bone and absorption of Ca from gut --> increased serum calcium

4

What are sources of Vit D?

Main source from sun exposure
10% from gut absorption
egg yolk, oily fish, fortified cereals and bread

5

What is the pathway that Vit D is synthesised from sun exposure?

Sun exposure
dehydro-cholesterol
Cholecalciferol (D3)
25 (OH) Vit D - liver
1, 25 (OH) Vit D - kidneys

6

In CKD why is there not enough Vit D?

In CKD they lack fine hydorxylation of 25 Vit D so not enough Vit D

7

What can cause hypercalcaemia?

1y hyperparathyroidism #1
Malignancy #1
Drugs – Vit D, thiazides
Granulomatous disease (Sarcoid, TB)
Familial Hypocalciuric hypercalcaemia
High Ca turnover – Pagets, bedridden, thyrotoxic
3y hyperparathyroidism
MEN1 & MEN2

8

How does hypercalcaemia present acutely?

thirst, dehydration, confusion and polyuria

9

In chronic hypercalcaemia, what S&S does the patient express?

myopathy, osteopaenia, fractures, depression, HTN, abdo pain (pancreatitis, ulcers, renal stones)

10

What investigations are required for the diagnosis of primary hypercalcaemia?

1y hypercalcaemia:
Increased serum Calcium
Increased serum PTH (or inappropriately abnormal)
Increased urine calcium excretion

11

What Ix are required for diagnosing hypercalcaemia associated with malignancy?

Increased serum Ca and ALP
X-ray, CT, MRI
Isotope bone scan

12

What treatment is required for acute hypercalcaemia?

Acute:
Rehydrate 0.9% saline 4-6L in 24hr
Consider loop diuretics
Bisphosphonates – single dose will lower Ca over 2-3 days, max effect at 1 week
Steroids – Prednisolone if Sarcoid

13

What treatment can be considered in malignant hypercalemia?

Salmon calcitonin – rarely used for malignant hypercalcaemia
Chemo – may reduce Ca in malignant disease (myeloma)

14

What is familial hypocalcimic hypercalcaemia?

Autosomal dominant inherited condition where there is a deactivating mutation in the calcium sensing receptor

15

What are the levels of calcium in familial hypocalcimic hypercalcaemia?

low urinary calcium
increased serum calcium

16

What is the presetation of familial hypocalcimic hypercalcaemia?

Usually benign and assymptomatic

17

Give the differential diagnosis for the following results:
hypercalcaemia
albumin normal/low
phosphate high
ALP low

Myeloma
Vit D excess
Mild-alkali syndrome (thyrotoxicosis, sarcoidosis, raised HCO3)

18

Give the differential diagnosis for the following results:
hypercalcaemia
albumin normal/low
phosphate high
ALP high

Bone metastases
Sarcoidosis
Thyrotoxicosis

19

What are the most common causes of hypocalcaemia?

Hypoparathyroidism
Vit D deficiency
Chronic renal failure

20

Give some rare causes of hypocalcaemia.

Pancreatitis
hyperventilation
osteoblastic bone mets
rhabdomyolysis

21

How does hypocalcaemia present?

Paraesthesia (fingers, toes, perioral)
Muscle cramps, tetany
Broncho or laryngospasm
Muscle weakness
Fatigue
Fits
Chovsteks sign (tap over facial nerve and get facial twitching)
Trousseau sign (carpopedal spasm)

22

What is the treatment for hypocalcaemia?

IV calcium gluconate 10ml 10% over 10 mins (in 50ml dextrose or saline)
Then
Infusion 10ml 10% in 100ml infusate at 50ml/h

23

What is the deficiency in rickets and osteomalacia?

Vitamin D deficiency

24

What are the S&S of rickets and osteomalacia?

Proximal myopathy
Dental defects (carries, enamel)
Bone – tenderness over sternum and shins, rib deformities, limb deformities

25

What are the causes of rickets and osteomalacia?

Malabsorption
Chronic renal failure
Lack of sunlight
Drugs (anticonvusants)
Dietary lack of Vit D

26

How do you decide between the diagnosis of rickets and osteomalacia?

Rickets occurs before the growth plates fuse

27

How should you treat chronic Vit D deficiency?

Vit D - Calcitriol or Alfacalcidol
Ca & Vit D – Adcal D3 (elerly with osteoporosis and fractures)

28

How does Paget's disease present?

Asymptomatic
Bone pain
Fractures
Nerve compression (deafness, cord compression)

29

What is the suspected aetiology of Paget's disease?

Viral trigger in genetically susceptible individual

30

How should Pagets disease be treated?

Only if symptomatic
analgesia first
orall bisphosphonates - Alendronate
Calcitonin

31

What causes hypoparathyroidism?

Congenital absence (DiGeorge syndrome)
Destruction of gland (surgery, radio, malignancy)
AI
Hypomagnesaemia
Idiopathic

32

What is the long term management of hypoparathyroidism?

Calcium supplements
Vit D tablets or depot injection

33

What are the 3 causes of hyperparathyroidsm?

1y – primary over activity of parathyroid e.g. adenoma

2y – physiological response to low Ca

3y – Parathyroid becomes autonomous after many years of 2y

34

Surgery or nothing are the treatment options for hyperparathyroidism. What are the indications for surgery?

End organ damage
Very high calcium (>2.85 mmol/l)
<60ml/min

35

In terms of PTH and Ca levels, what would you expect from 1y, 2y and 3y hyperparathyroidism?

1y - increased PTH and increased Ca
2y - increased PTH and low Ca
3y - increased PTH and increased Ca

36

What drug cna be used for 3y hyperparathyriodism or parathyroid carcinoma?

Cinacalcet