Clinical Calcium Homeostasis Flashcards by Lucy Jefford

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

How well did you know this?

Not at all

Perfectly

List the functions of calcium.

Bone formation
Cell division and growth
Muscle contraction
Neurotransmitter release

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

Where is the majority of the body’s calcium kept and stored?

Bone

How well did you know this?

Not at all

Perfectly

What proportion of calcium in the plasma is bound?

40% bound to plasma proteins
15% non-ionised or bound to complexes
45% free/ionised

How well did you know this?

Not at all

Perfectly

What is normal plasma calcium range?

2.2-2.6 mmol/l

How well did you know this?

Not at all

Perfectly

If there is increased albumin, what does this tell us about free calcium levels?

Decreased

How well did you know this?

Not at all

Perfectly

If there is decreased albumin, what does this tell us about free calcium levels?

Increased

How well did you know this?

Not at all

Perfectly

Acidosis increases ionised calcium. What can this predispose to?

Hypercalcaemia

How well did you know this?

Not at all

Perfectly

In which conditions would there be low albumin?

Malnutrition
Nephropathy

-> conditions in which patients lose a lot of protein in their urine

How well did you know this?

Not at all

Perfectly

Food sources of vitamin D?

Oily fish
Fortified fat spreads
Eggs
Fortified breakfast cereals

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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 well did you know this?

Not at all

Perfectly

How many parathyroid glands do we have?

How well did you know this?

Not at all

Perfectly

Parathyroid glands contain chief cells. What do these cells secrete?

PTH

How well did you know this?

Not at all

Perfectly

When calcium levels increase, what happens to PTH level?

Decease

-> and vice versa

How well did you know this?

Not at all

Perfectly

How does PTH increase calcium levels?

Promotes calcium reabsorption from renal tubules and bone

How well did you know this?

Not at all

Perfectly

Which form of vitamin D is primary obstained?

Vitamin D3

How well did you know this?

Not at all

Perfectly

What happens to vitamin D3?

Hydroxylated in the liver to form 25-hydroxyvitamin D which is an inactive form of vitamin D

How well did you know this?

Not at all

Perfectly

What is inactive vitamin D then activated into?

1,25- dihydroxyvitamin D

How well did you know this?

Not at all

Perfectly

List some of the acute neuromuscular features of hypocalcaemia.

Paraesthesia
Muscle twitching
Seizures
Laryngospasm
Bronchospasm
Trosseau’s sign
Chovtek’s sign

How well did you know this?

Not at all

Perfectly

Trousseau’s sign is associated with hypocalcaemia, what is it?

A sign of latent tetany used to determine hypocalcaemia

How well did you know this?

Not at all

Perfectly

What is Chvostek’s sign?

Twitch of facial muscles that occurs when gently tapping an individual’s cheek, it indicates hypocalcaemia

How well did you know this?

Not at all

Perfectly

What are some of the cardiac features of acute hypocalcaemia?

Prolonged QT interval
Hypotension
Heart failure
Arrhythmia
Papilledema

How well did you know this?

Not at all

Perfectly

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

Which drug can cause magnesium deficiency?

Omeprazole

Which investigations would be carried out if you suspected hypocalcaemia?

ECG Serum calcium Albumin levels Phosphate levels PTH U&Es Vitamin D Magnesium

What is th first thing to check in someone with hypocalcaemia?

PTH ->can be low or high in hypocalcaemia

What is the appropriate level of PTH is response to hypocalcaemia?

PTH levels should be high

List some of the causes of hypocalcaemia in which PTH levels would be low.

Genetic disorders Post-surgical Autoimmune

List some of the causes of hypocalcaemia in which PTH levels would be high.

Vitamin D deficiency Renal disease Acute pancreatitis Acute respiratory alkalosis Pseudohypoparathyroidism

If someone has hypocalcaemia and low PTH levels, what would you check next?

Magnesium levels

If someone has hypocalcaemia and high PTH levels, what would you check next?

Urea and creatine -> if high, renal failure. If normal, check vitamin D

What are the levels of the following in a vitamin D deficiency? 1. Calcium 2. Phosphate 3. PTH

1. Low 2. Low 3. High

What are the levels of the following in hypoparathyroidism? 1. Calcium 2. Phosphate 3. PTH

1. Low 2. High 3. Low

Hypoparrathyroidism?

Inappropriately low PTH in the context of hypocalcaemia

What are some of the causes of hypoparathyroidism?

Post surgery Autoimmune

Pseudohypoparathyroidism?

Group of heterogenous disorders defined by target organs (bone and kidney) having unresponsiveness to PTH

In pseudohypoparathyroidism, what are PTH levels like?

Elevated

What is the classical clinical feature of pseudohypoparathyroidism?

Shortening of the fourth and fifth metacarpals

What is the treatment for mild hypocalcaemia? (asymptomatic, >1.9mmol/l)

Oral calcium tablets If vit D deficient, start tablets If low Mg, replace Mg

What is the treatment of severe hypocalcaemia? (symptomatic or <1.9mm/l)

IV calcium gluconate Initial bolus Initial bolus repeated until patient is asymptomatic or levels significantly increased This is a medical emergency

What does the Scottish government recommend the public do regarding vitamin D?

Those five and above should consider taking a daily vit.D supplement of 10mg, particularly during Oct-Mar.

What can be said about a calcium level <3.0mmol/l?

Patient has hypercalcaemia. Often asymptomatic at this stage but usually requires urgent correction

What can be said about a calcium level 3.0-3.5mmol/l?

Patient has hypercalcaemia. May be well tolerated if risen slowly. May be symptomatic and prompt treatment usually indicated.

What can be said about a calcium level >3.5mmol/l?

The patient has hypercalcaemia. Requires urgent correction due to risk of dysrhythmia and coma

What are some of the more common causes of hypercalcaemia?

Primary hyperparathyroidism Hypercalcaemia of malignancy

Which medications can cause hypercalcaemia?

Thiazide diuretics Very high calcium and vit.D supplements

What are some of the renal features of hypercalcaemia?

Polyuria Polydipsia Nephrolithiasis-kidney stones

What are some of the GI features of hypercalcaemia?

Anorexia Nausea and vomiting Constipation Pancreatitis

What are some of the MSK features of hypercalcaemia?

Muscle weakness Bone pain Potentially osteoporosis -> the overall symptoms can be described as 'bones, stones and psychic moans'.

In hypercalcaemia, what is the appropriate response to PTH?

PTH low

Who is more likely to get primary hyperparathyroidism?

Female > male Incidence peak 50-60 yrs

What are the symptoms of primary hyperparathyroidism?

Bit of a trick question as usually asymptomatic at diagnosis

Which investigations are used to confirm the diagnosis of primary hyperparathyroidism?

Ca, PTH U&Es Abdominal imaging to check renal calculi DEXA to check for osteoporosis Spot urinary calcium/creatine ratio 24hr urinary calcium Vitamin D

Parathyroid imaging is not done to make a diagnosis but helps to localise adenoma so surgeons can have a targeted approach. In those <65, which two imaging techniques are carried out?

Ultrasound of parathyroid glands Sestamibi scan (nuclear)

In those over 65, what would be the imaging of choice in primary hyperparathyroidism to look for an adenoma?

CT scan

List some features that would be indicative for parathyroid surgery.

Any presence of symptoms A serum calcium >0.25mmol/l above upper limit of normal History pf osteoporosis or vertebral fractures Renal dysfunction <50yrs

What is the medical management of primary hyperparathyroidism?

Generous fluid intake Vitamin D replacement Cincalcet (mimics effect of calcium on the calcium sensing receptor in chief cells leading to a fall in PTH and subsequently calcium levels).

FFH (familial hypocalciuric hypercalcaemia)?

Autosomal dominant disorder of the calcium sensing receptor

What is the treatment of FFH?

No treatment required usually as only mild hypercalcaemia

What is MEN type 1?

Hereditary condition associated with tumours of the endocrine glands

Which type of tumours may MEN 1 encompass?

Primary hyperparathyroidism Pancreatic Pituitary

Which type of cancer does MEN type 2A typically present with?

Medullary thyroid cancer

What is involved in the management of hypercalcaemia?

Rehydration IV bisphosphonates

List some of the potential second line treatments for hypercalcaemia.

Glucocorticoids Calcitonin Calimemetrics Parathyroidectomy