hypocalcaemia and hypoparathyroidism

Question 1

most common causes hypocalcaemia

Answer 1

CKD (raised serum phosphate levels)
parathyroidectomy (decreased parathyroid function)

Drugs

Question 2

how does CKD cause hypocalcaemia?

Answer 2

inadequate production of active vitamin D and renal phosphate retention

–> micro precipitation of calcium phosphate in the tissues

Question 3

drugs that could cause hypocalcaemia?

Answer 3

calcitonin

bisphosphonates

Question 4

what does hypocalcaemia lead to? (clinically)

Answer 4

increased excitability of muscles and nerves

• numbness around mouth + in extremities, followed by cramps, tetany, convulsions + death if untreated

Question 5

A test for neuromuscular excitability?

Answer 5

Chvostek

• tap fail nerve in region of parotid gland and you’ll see twitching in the ipsilateral facial muscles

Question 6

what signs may severe hypocalaemia lead to?

Answer 6

papilloedema

prolonged QT interval on ECG

Question 7

Investigations

Answer 7

Hx + Ex

serum creatinine and eGFR (? CKD) and magnesium

Question 8

management acute e.g. with tetany

Answer 8

IV calcium gluconate + ECG monitoring

Question 9

Mx persistent hypocalcaemia in vitamin D deficiency

Answer 9

ergocalciferol (vit D2)

OR

cholecalciferol (vit D3)

Question 10

Mx for vitamin D deficiency if also have hypoparathyroidism?

Answer 10

vits D2 and D3 are ineffective and PTH is needed to convert them to 1-25-dihydroxyvitamin D

sooooo… use alfacalcidol (1alpha-hydroxycholecalciferol)