Clinical Calcium Homeostasis

Question 1

What are the dietary sources of calcium?

Answer 1

Dairy
Green leafy vegetables
Soya beans
Tofu
Nuts
Bread/anything made with fortified flour
Fish where you eat the bones

Question 2

What are the functions of calcium/

Answer 2

Bone formation
Cell division and growth
Muscle contraction
Neurotransmitter release

Question 3

What are the sources of vitamin D?

Answer 3

Sunlight
Oily fish
Eggs
Foritified fat spreads
Fortified breakfast cereals

Question 4

What groups are at risk of vitamin D deficiency?

Answer 4

Children
Pregnant women
People of colour
People who spend a lot of tine indoors ie nursing home residents
People who cover themselves up a lot ie Burkha

Question 5

What is the numerical definition of hypocalcaemia?

Answer 5

Serum calcium <2.20

Question 6

What are the clinical features of acute hypocalcaemia?

Answer 6

Neuromuscular irritability:
-Paraesthesia
-Muscle twitching
-Carpopedal spasm
-Trousseau's sign
-Chovstek's sign
-Seizures
-Laryngospasm
-Bronchospasm
Cardiac:
-Prolonged GT interval
-Hypotension
-Heart failure
-Arrhythmia
Papilloedema

Question 7

What are the clinical features of chronic hypocalcaemia?

Answer 7

Ectopic calcification
Extrapyramidal signs
Parkinsonism
Dementia
Subcapsular cataracts
Abnormal dentition
Dry skin

Question 8

What are the causes of hypocalcaemia?

Answer 8

Disruption of parathyroid gland (total thyroidectomy)
Selective parathyroidectomy
Severe vitamin D deficiency
Magnesium deficiency 
Cytotoxic drugs
Pancreatitis, rhabdomyolysis and large volume blood transfusions
Hypoparathyroidism 
Secondary hyperparathyroidism 
Drugs

Question 9

What history features would be suggestive of hypocalcaemia?

Answer 9

Reduced calcium or vitamin D intake
Neck surgery
Autoimmune disorders
Medications
Family history

Question 10

What investigations are useful in hypocalcaemia?

Answer 10

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

Question 11

What are the causes of hypoparathyroidism?

Answer 11

Agenesis
Destruction
Infiltration
Reduced secretion of PTH
Resistance to PTH

Question 12

What are the characteristics of pseudohypoparathyroidism?

Answer 12

Presents in childhood
Group of heterogenous disorders defined by kidney and bone unresponsiveness to PTH.
Characterised by hypocalcaemia, hyperphosphatemia and elevated PTH concentrations

Question 13

How is mild hypocalcaemia defined and treated?

Answer 13

Asymptomatic and >1.9mmol/L serum calcium
Commence oral calcium tablets
If post thyroidectomy repeat calcium 24hrs later
is vitamin D deficient, start vitamin D
If low Mg, stop any precipitating drug and replace Mg

Question 14

How is severe hypocalcaemia defined and treated?

Answer 14

Symptomatic or <1.9mmol/L serum calcium
MEDICAL EMERGENCY
Administer IV calcium gluconate
Initial bolus of calcium gluconate followed by infusion
Treat the underlying cause

Question 15

What are the causes of hypercalcemia?

Answer 15

Primary hyperparathyroidism
Hypercalcaemia of malignancy
Familial hypocalciuric hypercalcaemia
Tertiary hyperparathyroidism
Vitamin D intoxication
Chronic granulomatous disorders
Medications

Question 16

What are the clinical features of hypercalcaemia?

Answer 16

Renal:
-Polyuria
-Polydipsia
-Nephrolithiasis
Gastrointestinal:
-Anorexia
-Nausea and vomiting
-Constipation
Musculoskeletal:
-Muscle weakness
-Bone pain
Neurological:
-Decreased concentration
Cardiovascular:
-Shortening QT interval
"Bones, stones, groans and psychic moans"

Question 17

What signs on history and examination are suggestive of hypercalcaemia?

Answer 17

History:
-Symptoms of hypercalcaemia
-Systemic enquiry
-Medications
-Family history
Examination:
-Lymph nodes
-Concerns about malignancy

Question 18

What investigations can be useful in hypercalcaemia?

Answer 18

U&Es
Serum calcium
PO4
Alk phosphate
Myeloma screen
Serum ACE
PTH
Consider ECG

Question 19

How is primary hyperparathyroidism investigated?

Answer 19

Serum calcium
PTH
U&Es
Abdominal imaging for renal calculi
DEXA for osteoporosis
24 hour urine collection for calcium
Vitamin D

Question 20

When is parathyroid surgery indicated?

Answer 20

Presence of symptoms of hypercalcaemia
Serum calcium >0.25mmol/L above the upper limit of normal
Osteoporosis on DEXA
eDFR <60 
Presence of kidney stones
<50 years of age

Question 21

How is primary hyperparathyroidism managed medically?

Answer 21

Generous fluid intake

Cinacalcet

Question 22

What are the characteristics of familial hypocalciuric hypercalcaemia?

Answer 22

Autosomal dominant disorder of the calcium sensing receptor
Benign- no therapy indicated
If positive family history then screen young family members
PTH can be normal or slightly elevated

Question 23

What are the characteristics of multiple endocrine neoplasia type 1?

Answer 23

Presents as primary hyperparathyroidism with pancreatic and pituitary issues
Usually presents in the 2-4 decades of life

Question 24

What are the characteristics of multiple endocrine neoplasia type 2?

Answer 24

Can present as medullary thyroid cancer, phaeochromocytoma or primary hyperparathyroidism
Usually milder disease than MEN 1

Question 25

How is hypercalcaemia managed?

Answer 25

Rehydration- 0.9 saline 4-6 litres over 24 hours

After rehydration, intravenous bisphosphonates- zolendronic acid 4mg over 15 mins

Question 26

What is the second line management of hypercalcaemia?

Answer 26

Glucocorticoids, calcitonin, calcimimetics and parathyroidectomy