Calcium homeostasis and metabolism Flashcards

1
Q

How does hypocalcaemia present?

A
Paraesthesia (fingers, toes, perioral)
Muscle weakness
Tetany/cramps
Fatigue
Bronchospasm
Fits
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2
Q

Which two signs suggest hypocalaemia?

A

Chovsteks (facial nerve)

Trousseau (carpopedal spasm)

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3
Q

What is a sign of hypocalaemia on an ECG?

A

Prolonged QT interval

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4
Q

What are the causes of hypocalcaemia?

A
Hypoparathyroidism
Vitamin D deficiency (rickets, osteomalacia)
Chronic renal failure
Pancreatitis
Metastases 
Rhabdomyolysis (statins)
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5
Q

How is acute hypocalcaemia?

A

IV calcium gluconate

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6
Q

What are the causes of hypoparathyroidism?

A
DiGeorge syndrome
Autoimmune
Surgery/radiation
Malignancy
Hypomagnesaemia 
Idiopathic
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7
Q

What is the management of chronic hypocalcaemia?

A

Calcium supplement

Vitamin D - 1alpha calcidol (tablet) or cholecalciferol (injection)

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8
Q

How does hypomagnesaemia cause hypocalcaemia?

A

Magnesium is essential for calcium release from cells >
Intracellular calcium is high >
PTH release inhibited >
Skeletal and muscle receptors less sensitive to calcium

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9
Q

How is hypomagnesaemia treated?

A

Calcium and magnesium replacement

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10
Q

What are the causes of hypomagnesaemia?

A
Alcohol
Medication (thiazides, PPI)
GI illness
Pancreatitis 
Malabsorption
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11
Q

What is pseudohypoparathyroidism?

A

Genetic dysfunction of G protein Gs alpha subunit causing PTH resistance

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12
Q

How does pseudohypoparathyroidism present?

A
Low calcium
Elevated PTH 
Bone abnormalities/McCune Albright
Obesity 
Subcutaneous calcification
Learning disability 
Brachdactyly
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13
Q

What is pseudo-pseudohypoparathyroidism?

A

Pseudohypoparathyroidism but with normal calcium levels

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14
Q

Can you change between pseudo-pseudohypoparathyroidism to pseudohypoparathyroidism?

A

Yes

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15
Q

Where do humans get their vitamin D from?

A

The sun and their diet

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16
Q

How do the terms rickets and osteomalacia differ?

A

Softening of the bones
Rickets - children
Osteomalacia - adults

17
Q

How does vitamin D deficiency arise?

A
Dietary deficiency 
Lack of sunlight 
Malabsorption 
Chronic renal failure
Anticonvulsants
18
Q

How does osteomalacia present?

A
Low calcium 
Proximal myopathy
Rib deformity 
Limb deformity 
Bone tenderness
Pseudo/fractures 
Dental defects (caries)
19
Q

What x-ray feature is associated with vitamin D deficiency?

A

Looser zones/pseudofractures

20
Q

What deficiency does chronic renal failure cause?

A

Vitamin D deficiency –> secondary hypoparathyroidism

21
Q

What changes to vitamin D does chronic renal failure cause?

A

25 OH vit D may be normal or high

1,25 OH vit D will be low

22
Q

How should chronic renal failure be treated in terms of vitamin D correction?

A
Titrate levels of vitamin D to match PTH
Phosphate binders (to get rid of elevated blood phosphate)
23
Q

What are the biochemical results of someone with UV related vitamin D deficiency?

A
Low calcium
Low phosphate
High alk phosphate
Low vitamin D
High PTH
24
Q

What are the long term risks of vitamin D deficiency?

A
Fractures
Osteomalacia/rickets
Colonic cancer 
Diabetes
Heart disease
25
Q

What is the treatment for chronic vitamin D deficiency?

A

Vitamin D3 tablets
Calcitriol
Alfacalcidol

Adcal D3 (calcium + vit D)

26
Q

What is X-linked hypophosphataemia? What other name does it go by?

A

Genetic mutation causing decreased phosphate reabsorption and thus rickets
Vitamin D resistant rickets

27
Q

What is the biochemical profile of someone with hypophosphataemia?

A

High vitamin D

Low phosphate

28
Q

How is X-linked hypophosphataemia managed?

A

Phosphate and vitamin D supplements +/- surgery to correct genu varum