Hypercalcaemia Flashcards
What level of calcium is defined as hypercalcaemia?
> 10.5mg/dL.
Where is calcium distributed in the body?
99% in bones as calcium phosphate (hydroxyapatite).
1% split into:
0.99% extracellular in blood and interstitial space
0.1% is intracellular.
What does calcium do in cells?
causes cell apoptosis so cells try and keep their intracellular calcium levels low.
How does calcium enter cells?
Ligand gated channels (most cells)
voltage gated channels (found in muscles and nerves).
How does calcium exit cells?
ATP dependant calcium pumps and sodium calcium exchangers.
Where is calcium stored when in cells?
Mitochondria
Endoplasmic reticulum
Which part of the body detects low calcium levels?
the parathyroid gland
What hormone is secreted when the body has low calcium?
parathyroid hormone - increases bone resorption + makes kidneys reabsorb calcium
calcitriol (active vitamin D) - causes the GI tract to increase calcium absorption
Which hormone reduces calcium levels in the body?
Calcitonin (the opposite function of calcitriol and parathyroid hormone).
What should the NORMAL level of extracellular calcium be?
8.5-10mg/dL
Which pH increases free calcium?
acidosis - because the positive H+ ions fight to bind where calcium normally does meaning theres increased levels of unbound calcium.
What is the most common cause of hypercalcaemia?
Hyperparathyroidism
What are other causes of hypercalcaemia?
Malignancy (malignant tumours often release ectopic proteins that mimic parathyroid hormone and simulates osteoclasts) - they also cause osteoblasts to die.
Which medications can cause hyperparathyroidism?
Thiazide diuretics
Vitamin D
Vitamin A
Calcium
How does hyperparathyroidism cause hypercalcaemia?
too much parathyroid hormone causes osteoclasts to increase in activity - causing increased bone breakdown and release of calcium into the blood.
What are signs of hypercalcaemia?
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
What are the complications of hypercalciuria?
Increased urine loss causing dehydration
formation of calcium oxalate stones
What ECG changes can hypercalcaemia cause?
tachycardia
AV block
Shortening QT interval
How is hypercalcaemia diagnosed?
calcium levels >10.5mg/dL
What is the treatment for hypercalcaemia?
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.
Which common endocrine condition causes hypercalcaemia?
Hyperparathyroidism.
