Clinical Calcium Homeostasis Flashcards
LIST SOME DIETARY SOURCES OF CALCIUM WHOOOOOOOOOOOOOOOOOO GO GIRL GO
Milk, cheese, dairy
Green leafy veg
Soya beans
Tofu
Nuts
Fish w bones e.g sardines and pilchards.
Anything w fortified flour
List the functions of calcium.
Bone formation
Cell division and growth
Muscle contraction
Neurotransmitter release
80% approx. of calcium consumed through diet is not absorbed. Why?
Forms insoluble salts e.g. calcium phosphate or calcium oxalate which cannot be absorbed by the body
Where is the majority of the body’s calcium kept and stored?
Bone
What proportion of calcium in the plasma is bound?
40% bound to plasma proteins
15% non-ionised or bound to complexes
45% free/ionised
What is normal plasma calcium range?
2.2-2.6 mmol/l
If there is increased albumin, what does this tell us about free calcium levels?
Decreased
If there is decreased albumin, what does this tell us about free calcium levels?
Increased
Acidosis increases ionised calcium. What can this predispose to?
Hypercalcaemia
In which conditions would there be low albumin?
Malnutrition
Nephropathy
-> conditions in which patients lose a lot of protein in their urine
Food sources of vitamin D?
Oily fish
Fortified fat spreads
Eggs
Fortified breakfast cereals
What is the best source of vitamin D?
The sun
-> the body must be exposed sufficiently to strong sunlight in order to get vitamin D
Which groups of people are at higher risk of a vitamin D deficiency?
Pregnant
Children
Those in care
Those who don’t get much sunlight
Those with darker skin tone
How many parathyroid glands do we have?
4
Parathyroid glands contain chief cells. What do these cells secrete?
PTH
When calcium levels increase, what happens to PTH level?
Decease
-> and vice versa
How does PTH increase calcium levels?
Promotes calcium reabsorption from renal tubules and bone
Which form of vitamin D is primary obstained?
Vitamin D3
What happens to vitamin D3?
Hydroxylated in the liver to form 25-hydroxyvitamin D which is an inactive form of vitamin D
What is inactive vitamin D then activated into?
1,25- dihydroxyvitamin D
List some of the acute neuromuscular features of hypocalcaemia.
Paraesthesia
Muscle twitching
Seizures
Laryngospasm
Bronchospasm
Trosseau’s sign
Chovtek’s sign
Trousseau’s sign is associated with hypocalcaemia, what is it?
A sign of latent tetany used to determine hypocalcaemia
What is Chvostek’s sign?
Twitch of facial muscles that occurs when gently tapping an individual’s cheek, it indicates hypocalcaemia
What are some of the cardiac features of acute hypocalcaemia?
Prolonged QT interval
Hypotension
Heart failure
Arrhythmia
Papilledema
What are some of the features of chronic hypocalcaemia?
Ectopic calcification
Parkinsonism
Dementia
Dry skin
Abnormal dentition
Subcapsular cataracts
At which level of calcium do the features of hypocalcaemia tend to arise?
If calcium levels drop below 1.9mm/l
List some of the causes of hypocalcaemia.
Disruption of parathyroid gland, usually due to total thyroidectomy
Severe vitamin D deficiency
Magnesium deficiency
Cytotoxic drug-related hypocalcaemia
Pancreatitis
Large volume blood transfusions