Hypocalcemia

Question 1

What is the definition?

Answer 1

Common in patients who have been admitted to hospital
Acute hypocalcaemia that is severe (<1.9mmol/L) or is symptomatic is life threatening and needs URGENT treatment
Often initially picked up when low ionised calcium on BG as usually bone profiles are not usually done
Results in increased NM activity- paraesthesia, cramps, carpo-pedal spasms, laryngeal stridor and convulsions

Question 2

What are the causes of hypocalcaemia?

Answer 2

Increased phosphate levels: CKD, phosphate therapy, hyperphosphataemia

Hypoparathyroidism: Surgical e.g after neck exploration (thyroidectomy, parathyroidectomy) - (common), Congenital deficiency (DiGeorge’s syndrome), Idiopathic hypoparathyroidism (rare) - autoimmune disease, Severe hypomagnesaemia (due to end organ PTH resistance)

Vitamin D deficiency: osteomalacia/rickets, vitamin D resistance

Resistance to PTH: Pseudohypoparathyroidism-

Drugs

Other: Renal failure, Acute pancreatitis (quite common), Acute rhabdomyolysis (initially), Tumour necrosis syndrome, Citrated blood in massive transfusion (not uncommon), Low plasma albumin e.g malnutrition, chronic liver disease, Malabsorption e.g coeliac disease, Low magnesium can cause hypocalcaemia without a total change in calcium!, Over hydration, Severe sepsis, Refeeding syndrome, Respiratory alkalosis (total Ca2+ is normal, but reduced ionized Ca2+ as high PH)

Question 3

What are the drug causes of hypocalcaemia

Answer 3

• Calcitonin
  
  • Bisphosphonates
  • Cisplatin
  • Loop diuretics
  • Glucocorticoids
  • Gentamicin
  • Phosphates
• Theophylline

Question 4

What are the fclinical features of hypocalcalemia

Answer 4

• Neuromuscular irritability 
	• Muscular cramps 
	• Tetany
	• Spasm including laryngospasm, Shortness of breath due to bronchospasm
	• Distal paraesthesia
• Neuropsychiatric manifestations 
	• Confusion 
	• Hallucinations 
	• Seizures - reduced threshold
	• Depression long term
• Bilary and intestinal colic (Caused by smooth muscle contraction) 
•  ECG: prolonged QT interval
Can also see cataracts  long term

Question 5

What is the menemonic spasmodic

Answer 5

S: Spasm (carpopedal- trousseau’s
P: perioral paraesthesia
A: anxious, irritable, irrational
S: seizures
M: muscle tone increase: hence colic, wheeze, dysphagia
O: orientation impaired (time, place, person) confusion
D: dermatitis (e.g atopic/exfoliative)
I: impetigo herpetiformis (decrease calcium and pustules in pregnancy rare and serious-severe pustular psoriasis)
C: chvostek’s sign, choreoathetosis (occurrence of involuntary movements in a combination of chorea and athetosis this is abnormal muscle movements), cataracts, cardiomyopathy (low QT interval)

Question 6

What is chovstek sign

Answer 6

gently tapping on the facial nerve causes twitching of the ipsilateral facial muscle

Question 7

What is trousseau’s sign

Answer 7

where inflation of the sphygmomanometer cuff above systolic pressure for 3 minutes induces tetanic spasm of the fingers and wrist by making it ischaemic - carpopedal spasm

Question 8

How do you investigate hypocalcaemia

Answer 8

• History
• Examination
○ ECG: arrythmias (prolonged ST, prolonged QT, and torsade’s de points)
• Blood tests:
○ Bone profile, U&E, Mg, VitD, PTH
Determine the correct calcium (protein bound) and ionized (free calcium), phosphate, and parathyroid hormone, albumin, magnesium
In hypocalcaemia- PTH is increased except in causes of hypoparathyroidism when PTH is low or low normal
Consider amylase/lipase (pancreatitis) and CK (rhabdomyolysis) as clinical indicated

Question 9

How do you manage

Answer 9

Attempts should be made to raise calcium when plasma (adjusted) calcium is <1.8mmol/L or patient has signs of hypo calcium i.e tetany or signs or seizures

Question 10

How do you manage mild hypocalcaemia (>1.9mmol/L)

Answer 10

• Start oral replacement using sandrocal (2 tablets BD) or Adcal (3 tablets BD) or any other available)
• Treat the underlying cause:
○ Stop drugs
○ Vitamin D- load with 300,000 units as per local
○ Hypomagnesaemia - IV mg (usually need 24mmol or 6g in 24hrs) stop any drugs e.g PPIs
○ Thyroidectomy/parathyroidectomy- may need 1 alpha hydroxylated vitamin D- start with specialist

Question 11

How do you manage Severe (<1.9mmol/L or symptomatic)

Answer 11

• This is a medical emergency & should be treated whilst on a cardiac monitor
• Example regime could be:
• 10-20ml 10% calcium gluconate in 50-100ml of 5% dextrose over 10 minutes
• Calcium gluconate infusion – 100ml 10% calcium gluconate in 1L 0.9% saline/5% dextrose at 50-100ml/h
• Treat the underlying cause as above
Ensure referral to the endocrinology team