Calcium and PTH

Question 1

how should you go about treating hypercalcaemia

Answer 1

Stop offending medication etc., rehydrate with normal saline (3-4 litres in 24 hours), considera loop diuretic to promote calciuria, bisphosphonates, steroids (Effective in haematological malignancy; vitamin D intoxication; granulomatous disease)

Question 2

what is the main cause of primary hyperparathyroidism ?

What is the second most common cause of hyperparathyroidism ?

Answer 2

parathyroid adenoma 
parathyroid hyperplasia (2nd) - usually associated with familial conditions

Question 3

name some of the end organ damage that can occur due to primary hyperparathyroidism

Answer 3

osteoporosis, boney cysts, kidney - renal calliculi and nephrocalcinosis and renal impairment. Can also cause pancreatitis

Question 4

describe some of the possible complications from a parathyroidectomy

Answer 4

Mechanical
• Vocal cord paresis
• Haematoma causing tracheal compression
Metabolic
• Transient hypocalcaemia (suppression of remaining glands)
• May require oral calcium / vit D supplementation

“hungry bones”
• Uncommon
• Occurs in patients who have significant bone disease pre-op or very elevated PTH.
• Sudden withdrawal of PTH leads to imbalance between bone formation and resorption – marked net increase in uptake of calcium, phosphate and magnesium by bone
• Requires calcium and vitamin D supplementation

Question 5

why might a person be deficient in vitamin D ? Name a complication of long-term vitamin D deficiency

Answer 5

• Poor sunlight exposure (i.e. elderly or housebound)
• Malabsorption
• Gastrectomy
• Enzyme inducing drugs e.g. anticonvulsants
• Renal disease (impaired hydroxylation of 250H Calcitriol)
osteomalacia (would see very high Alk Phos levels)

Question 6

what would you give a vitamin D deficient patient with real disease

Answer 6

Alfacalcidol (active form of vitamin D)

Would give a normal person cholecalciferol

Question 7

in a situation of high PTH what can happen to the phosphate levels in the blood

Answer 7

become excessively high

Question 8

in osteoporosis how would you give PTH

Answer 8

in an intermittent fashion - increases anabolic activity of osteoblasts.

Question 9

if you had a loss of function mutation in your Parathyroid gland what condition would this be associated with?

Answer 9

familial hypocalciuric hypercalcaemia

Question 10

name three areas where the calcium sensing receptor is expressed

Answer 10

Parathyroid gland, kidney, thyroid gland

Question 11

list the actions of vitamin D

Answer 11

• Increases calcium and phosphate absorption from the gut
• Bone mineralisation and mobilise calcium stores
• Immunomodulation – B and T cells
• Increases muscle strength
• Reduces insulin resistance
• Interacts with RAAS, may have a role in prevention of CJD

Question 12

above what level does calcium begin to give a patient symptoms

Answer 12

3 mmol/l

Question 13

name three drugs that can give hypercalcaemia

Answer 13

lithium, thiazide diuretics, calcium supplements

Question 14

in a situation of high PTH and high calcium what are your differentials

Answer 14

hyperparathyroidism, FHH and lithium

Question 15

in a situation of low PTH and high calcium what are your differentials

Answer 15

this would be parathyroid independent disease so would include malignancy, granulomatous disease, calcium supplements etc.

Question 16

give 3 ways in which malignancy can cause hypercalcaemia

Answer 16

osteolytic metastases and myeloma, tumour secretion of PTHrp and tumour production of vitamin D