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Endocrine > Calcium Homeostasis and Disorders > Flashcards

Calcium Homeostasis and Disorders Flashcards

1
Q

What is the recommended daily dose of calcium?

A

700mg

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2
Q

What 4 factors contribute to Calcium homeostasis?

A

Diet
Gut absorption
PTH
Vit D

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3
Q

Briefly explain the pathway that leads to increased serum calcium.

A

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

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4
Q

What are sources of Vit D?

A

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

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5
Q

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

A 
Sun exposure 
dehydro-cholesterol 
Cholecalciferol (D3)
25 (OH) Vit D - liver 
1, 25 (OH) Vit D - kidneys
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6
Q

In CKD why is there not enough Vit D?

A

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

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7
Q

What can cause hypercalcaemia?

A 
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
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8
Q

How does hypercalcaemia present acutely?

A

thirst, dehydration, confusion and polyuria

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9
Q

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

A

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

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10
Q

What investigations are required for the diagnosis of primary hypercalcaemia?

A

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

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11
Q

What Ix are required for diagnosing hypercalcaemia associated with malignancy?

A

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

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12
Q

What treatment is required for acute hypercalcaemia?

A 
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
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13
Q

What treatment can be considered in malignant hypercalemia?

A

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

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14
Q

What is familial hypocalcimic hypercalcaemia?

A

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

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15
Q

What are the levels of calcium in familial hypocalcimic hypercalcaemia?

A

low urinary calcium

increased serum calcium

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16
Q

What is the presetation of familial hypocalcimic hypercalcaemia?

A

Usually benign and assymptomatic

17
Q 
Give the differential diagnosis for the following results:
hypercalcaemia 
albumin normal/low 
phosphate high 
ALP low
A

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

18
Q 
Give the differential diagnosis for the following results:
hypercalcaemia 
albumin normal/low 
phosphate high 
ALP high
A

Bone metastases
Sarcoidosis
Thyrotoxicosis

19
Q

What are the most common causes of hypocalcaemia?

A

Hypoparathyroidism
Vit D deficiency
Chronic renal failure

20
Q

Give some rare causes of hypocalcaemia.

A

Pancreatitis
hyperventilation
osteoblastic bone mets
rhabdomyolysis

21
Q

How does hypocalcaemia present?

A 
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
Q

What is the treatment for hypocalcaemia?

A

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

23
Q

What is the deficiency in rickets and osteomalacia?

A

Vitamin D deficiency

24
Q

What are the S&S of rickets and osteomalacia?

A 
Proximal myopathy 
Dental defects (carries, enamel)
Bone – tenderness over sternum and shins, rib deformities, limb deformities
25
Q

What are the causes of rickets and osteomalacia?

A 
Malabsorption 
Chronic renal failure 
Lack of sunlight 
Drugs (anticonvusants)
Dietary lack of Vit D
26
Q

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

A

Rickets occurs before the growth plates fuse

27
Q

How should you treat chronic Vit D deficiency?

A

Vit D - Calcitriol or Alfacalcidol

Ca & Vit D – Adcal D3 (elerly with osteoporosis and fractures)

28
Q

How does Paget’s disease present?

A

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

29
Q

What is the suspected aetiology of Paget’s disease?

A

Viral trigger in genetically susceptible individual

30
Q

How should Pagets disease be treated?

A

Only if symptomatic
analgesia first
orall bisphosphonates - Alendronate
Calcitonin

31
Q

What causes hypoparathyroidism?

A 
Congenital absence (DiGeorge syndrome) 
Destruction of gland (surgery, radio, malignancy)
AI 
Hypomagnesaemia 
Idiopathic
32
Q

What is the long term management of hypoparathyroidism?

A

Calcium supplements

Vit D tablets or depot injection

33
Q

What are the 3 causes of hyperparathyroidsm?

A

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
Q

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

A

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

35
Q

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

A

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

36
Q

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

A

Cinacalcet

Endocrine (18 decks)

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