Hypocalcaemia

Question 1

what is the most common causes of hypocalcaemia?

Answer 1

vitamin D deficiency
Magnesium deficiency
renal disease
drug induced i.e. bisphosphonates, calcitonin
post operative - thyroidectomy, parathyroidectomy

Question 2

if there is hypocalcaemia with high PTH levels, is this primary or secondary hyperparathyroidism?

Answer 2

primary hyperparathyroidism as the PTH’s are increases physiologically in response to low Ca

Question 3

what is the normal range of free calcium?

Answer 3

2.2-2.6 mmol/L

Question 4

what is corrected Ca and how is it calculated?

Answer 4

if someone has a decreased albumin then their free Ca will increase.
adjust Ca by 0.1mmol/L for each 5g/L decrease in albumin from 40g/L to get their corrected Ca concentration

Question 5

does acidosis predispose a patient to hypo or hypercalcaemia and why?

Answer 5

acidosis increases ionised Ca therefore predisposes to hyeprcalcaemia

Question 6

what cells in the parathyroid gland respond directly to changes in Ca?

Answer 6

chief cells

Question 7

where does the conversion of inactive vitamin D to active vitamin D occur?

Answer 7

the kidneys

Question 8

what patients may need active vitamin D supplements?

Answer 8

patients with kidney disease as they won’t be able to convert inactive to active form

Question 9

what is the level of Ca which is hypocalcaemia? and at what level does symptoms show?

Answer 9

serum Ca <2.20 mol/L

symptoms show < 1.9 mmol/L

Question 10

what are the clinical features of hypocalcaemia?

Answer 10

muscle twitching
paraesthesia 
chovstek's sign
trousseau's sign 
seizures
laryngospasm, bronchospasm
carpopedal spasm 
papilloedema 
cardiac features

Question 11

what are the cardiac clinical features of hypocalcaemia?

Answer 11

prolonged QT interval
hypotension
heart failure
arrhythmia

Question 12

what are the chronic clinical features of hypocalcaemia?

Answer 12

dry skin
ectopic calcification in basal ganglia
extrapyramidal signs
parkinsonism
dementia
sub capsular cataracts 
abnormal dentition

Question 13

what can cause low PTH release resulting in hypocalcaemia?

Answer 13

thyroidectomy / parathyroidectomy 
autoimmune
genetic disorders
radiation induced 
HIV infection
infiltration - Sarcoidosis, haemochromatosis, mets

Question 14

what drugs can cause hypocalcaemia?

Answer 14

bisphophonates
calcitonin
phenytoin
fluoride poisoning

Question 15

is someone presented with hypocalcaemia, what blood tests would you carry out?

Answer 15

vitamin D
magnesium 
U & E's 
albumin 
PTH 
serum Ca
phosphate

Question 16

what is the next investigation you would carry out if someone presented with hypocalcaemia and high PTH ?
what would causes could this indicate?

Answer 16

check urea and creatinine 
if low = renal failure 
if normal check vitamin D
if low = vitamin D deficiency
if normal = pseudohypoparathyroidism or Ca deficiency

Question 17

if someone presents with hypocalcaemia and low/normal PTH, would would be the next investigation you would carry out?
what would these results indicate?

Answer 17

check magnesium
if low = magnesium deficient
if normal = hypoparathyroidism

Question 18

what is pseudohypoparathyroidism?

Answer 18

group of heterogeneous disorders defined by a target organs unresponsiveness to PTH (kidney & bone)

Question 19

in what condition is shortening of the metacarpal bones found ?

Answer 19

pseudohypoparathyroidism

albright’s hereditary osteodystrophy

Question 20

what may be the cause of hypoparathyroidism?

Answer 20

magnesium deficiency 
pseudohypoparathyroidism
destruction - neck surgery, autoimmune
genesis - di george syndrome
infiltration - haemochromatosis, wilsons disease

Question 21

what is the treatment for hypocalcaemia?

Answer 21

mild asymptomatic (>1.9)
- oral Ca tablet 
- vitamin D replacement if deficient
- Mg if deficient 
severe - symptomatic or < 1.9
- IV Ca gluconate

Question 22

because people with renal impairment can’t convert inactive vitamin D to active, what alternative treatment can they get to correct Vitamin D deficiency?

Answer 22

calciferol

alfacalciferol

Question 23

what results on the blood test would indicate the cause of hypocalcaemia is primary hypothyroidism?

Answer 23

elevated Ca
reduced PTH
elevated phosphate

Question 24

what are the results of Ca, PTH and phosphate in someone with pseudohypoparathyroidism?

Answer 24

low Ca
elevated PTH
elevated phosphate

Question 25

what are the complications of pseudohypoparathyroidism?

Answer 25

albrights hereditary osteodystrophy
short stature
obesity
shortening of the metacarpals