Calcium homeostasis and physiology

Question 1

What are the acute symptoms of hypercalcaemia ?

Answer 1

• Thirst
• Dehydration
• Confusion
• Polyuria

Question 2

What are the chronic symptoms/signs of hypercalcaemia ?

Answer 2

• Myopathy - muscle weakness
• Osteopaenia/fractures
• Depression
• Hypertension
• Abdominal pain- pancreatitis
• Ulcers
• Renal stones

Think stones, groans, bone and psychic moans

Question 3

What are the 2 most common causes of hypercalcaemia ?

Answer 3

1. Primary Hyperparathyroidism
2. Malignancy

Question 4

What are the results which would suggest a diagnosis of primary hyperparathyroidism?

Answer 4

• Raised serum calcium
• Raised serum PTH (or inappropriately normal)
• Increased urine calcium excretion

Question 5

Describe the pathway of result which would point you to a diganosis of primary hyperparathyroidism causing the hypercalcaemia ?

Answer 5

1. Albumin normal
2. PTH high and phosphate low
3. Increased urine calcium and serum calcium

Then it is due to primary hyperparathyroidism

Question 6

Describe the pathway of tests which would point to a diagnosis of malignancy causing hypercalcaemia

Answer 6

1. Albumin normal
2. PTH suppressed and phosphate high
3. Alk phosphate high

Think malignancy

Question 7

What is the acute management of hypercalcaemia ?

Answer 7

• Fluids - remember anything that is too high try to dilute
• Consider loop diuretics once rehydrated- avoid thiazides
• Bisphosphonates- single dose will lower Ca over 2-3d, maximum effect at 1 week

Question 8

What is the treatment of primary hyperparathyroidism?

Answer 8

Surgery or nothing as may not be required

Question 9

What are the indications for doing a parathyroidectomy for primary hyperparathyroidism ?

Answer 9

End Organ Damage:

• Bone disease
• Gastric ulcers
• Renal stones
• Osteoporosis

Very high Calcium (>2.85mmol/l)

Under age 50

GFR < 60 mL/min

Question 10

What are the different types of hyperparathyoidism ?

Answer 10

Primary, secondary and tertiary

Question 11

How do you distinguish between primary, secondary and tertiary hyperparathyroidism?

Answer 11

• Primary - PTH raised, Ca raised. Due to overactivity of parathyroid
• Secondary - Ca low, PTH raised. Due to response to low Ca
• Tertiary - PTH raised, Ca raised. Due to parathyroid becoming autonomous after many years of secondary

Question 12

What are the genetic syndrome linked to hypercalcaemia ?

Answer 12

• MEN1/2
• Familial Hypocalciuric Hypercalcaemia

Question 13

What are the biochem features of Familial Hypocalciuric Hypercalcaemia?

Answer 13

• Mild Hypercalaemia
• Reduced urine calcium excretion
• PTH may be (marginally) elevated

Question 14

What symptoms are key pointers towards hypocalcaemia compared to other electrolyte disturbances ?

Answer 14

Paraesthesia and bronchospasm (SOB)