Calcium homeostasis and metabolism Flashcards Preview

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Flashcards in Calcium homeostasis and metabolism Deck (28):
1

How does hypocalcaemia present?

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

2

Which two signs suggest hypocalaemia?

Chovsteks (facial nerve)
Trousseau (carpopedal spasm)

3

What is a sign of hypocalaemia on an ECG?

Prolonged QT interval

4

What are the causes of hypocalcaemia?

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

5

How is acute hypocalcaemia?

IV calcium gluconate

6

What are the causes of hypoparathyroidism?

DiGeorge syndrome
Autoimmune
Surgery/radiation
Malignancy
Hypomagnesaemia
Idiopathic

7

What is the management of chronic hypocalcaemia?

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

8

How does hypomagnesaemia cause hypocalcaemia?

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

9

How is hypomagnesaemia treated?

Calcium and magnesium replacement

10

What are the causes of hypomagnesaemia?

Alcohol
Medication (thiazides, PPI)
GI illness
Pancreatitis
Malabsorption

11

What is pseudohypoparathyroidism?

Genetic dysfunction of G protein Gs alpha subunit causing PTH resistance

12

How does pseudohypoparathyroidism present?

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

13

What is pseudo-pseudohypoparathyroidism?

Pseudohypoparathyroidism but with normal calcium levels

14

Can you change between pseudo-pseudohypoparathyroidism to pseudohypoparathyroidism?

Yes

15

Where do humans get their vitamin D from?

The sun and their diet

16

How do the terms rickets and osteomalacia differ?

Softening of the bones
Rickets - children
Osteomalacia - adults

17

How does vitamin D deficiency arise?

Dietary deficiency
Lack of sunlight
Malabsorption
Chronic renal failure
Anticonvulsants

18

How does osteomalacia present?

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

19

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

Looser zones/pseudofractures

20

What deficiency does chronic renal failure cause?

Vitamin D deficiency --> secondary hypoparathyroidism

21

What changes to vitamin D does chronic renal failure cause?

25 OH vit D may be normal or high
1,25 OH vit D will be low

22

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

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

23

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

Low calcium
Low phosphate
High alk phosphate
Low vitamin D
High PTH

24

What are the long term risks of vitamin D deficiency?

Fractures
Osteomalacia/rickets
Colonic cancer
Diabetes
Heart disease

25

What is the treatment for chronic vitamin D deficiency?

Vitamin D3 tablets
Calcitriol
Alfacalcidol

Adcal D3 (calcium + vit D)

26

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

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

27

What is the biochemical profile of someone with hypophosphataemia?

High vitamin D
Low phosphate

28

How is X-linked hypophosphataemia managed?

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

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