Hypercalcaemia

Question 1

What level of calcium is defined as hypercalcaemia?

Answer 1

> 10.5mg/dL.

Question 2

Where is calcium distributed in the body?

Answer 2

99% in bones as calcium phosphate (hydroxyapatite).
1% split into:
0.99% extracellular in blood and interstitial space
0.1% is intracellular.

Question 3

What does calcium do in cells?

Answer 3

causes cell apoptosis so cells try and keep their intracellular calcium levels low.

Question 4

How does calcium enter cells?

Answer 4

Ligand gated channels (most cells)

voltage gated channels (found in muscles and nerves).

Question 5

How does calcium exit cells?

Answer 5

ATP dependant calcium pumps and sodium calcium exchangers.

Question 6

Where is calcium stored when in cells?

Answer 6

Mitochondria

Endoplasmic reticulum

Question 7

Which part of the body detects low calcium levels?

Answer 7

the parathyroid gland

Question 8

What hormone is secreted when the body has low calcium?

Answer 8

parathyroid hormone - increases bone resorption + makes kidneys reabsorb calcium
calcitriol (active vitamin D) - causes the GI tract to increase calcium absorption

Question 9

Which hormone reduces calcium levels in the body?

Answer 9

Calcitonin (the opposite function of calcitriol and parathyroid hormone).

Question 10

What should the NORMAL level of extracellular calcium be?

Answer 10

8.5-10mg/dL

Question 11

Which pH increases free calcium?

Answer 11

acidosis - because the positive H+ ions fight to bind where calcium normally does meaning theres increased levels of unbound calcium.

Question 12

What is the most common cause of hypercalcaemia?

Answer 12

Hyperparathyroidism

Question 13

What are other causes of hypercalcaemia?

Answer 13

Malignancy (malignant tumours often release ectopic proteins that mimic parathyroid hormone and simulates osteoclasts) - they also cause osteoblasts to die.

Question 14

Which medications can cause hyperparathyroidism?

Answer 14

Thiazide diuretics
Vitamin D
Vitamin A
Calcium

Question 15

How does hyperparathyroidism cause hypercalcaemia?

Answer 15

too much parathyroid hormone causes osteoclasts to increase in activity - causing increased bone breakdown and release of calcium into the blood.

Question 16

What are signs of hypercalcaemia?

Answer 16

bone pain, 
osteoporosis, 
fatigue, 
hallucinations,
stupor, 
hypercalciuria 
confusion, 
memory problems, 
depression, 
nausea, 
vomiting, 
abdominal pain, 
weight loss, thirst, 
polyuria, 
constipation, 
abdominal pain, 
renal colic, or
renal impairment

Question 17

What are the complications of hypercalciuria?

Answer 17

Increased urine loss causing dehydration

formation of calcium oxalate stones

Question 18

What ECG changes can hypercalcaemia cause?

Answer 18

tachycardia
AV block
Shortening QT interval

Question 19

How is hypercalcaemia diagnosed?

Answer 19

calcium levels >10.5mg/dL

Question 20

What is the treatment for hypercalcaemia?

Answer 20

Rehydration - causing more urinary excretion of calcium
Loop diuretics (blocks calcium reabsorption at the loop of henle)
Glucocorticoids (increases GI excretion + decreases calcium absorption)
Bisphosphonates - prevents bone resorption
Calcitonin - inhibits osteoclasts.

Question 21

Which common endocrine condition causes hypercalcaemia?

Answer 21

Hyperparathyroidism.