Introduction
This can be spurious and/or as a result of low albumin levels although most labs correct for albumin levels.
Causes
Vitamin D deficiency
Asian population
Chronic renal failure
Pregnancy/breast feeding
Loss of calcium from circulation
Hyperphosphataemia
Acute pancreatitis (sequestration)
Osteoblastic metastases
Citrate or blood products
Acute respiratory alkalosis
Hypoparathyroidism
Post operative (hungry bones)
Idiopathic
Pseudo-hypoparathyroidism
Infiltration
HIV
Hypomagnesaemia (drug induced e.g. PPI, diuretics)
Sepsis, burns
Fluoride intoxication
Chemotherapy
Presentation
Mild hypocalcaemia can be asymptomatic (>1.9mmol/l).
Early Features:
Anxiety and nervousness
Paraesthesia around mouth and in fingers and toes
Late features
Convulsions
Tetany
Prolonged QT, hypotension, bradycardia
Papilloedema
Muscle cramps and twitches
Chovstek’s sign (contraction of facial muscles after tapping the facial nerve anterior to the ear)
Trousseau’s sign (carpal spasm after inflation of a blood pressure cuff for 3-5 minutes)
Investigation
Plasma calcium (bone group), phosphate and albumin
Magnesium
U&Es
ECG (prolonged QT)
Plasma PTH (this may not be elevated if Mg2 is low)
Alk phos
Vit D
Treatment
The aim of acute management is resolution of symptoms, not restoration of normal calcium levels.
For severe complications:
Calcium gluconate 10%. 10mls IV by slow injection over 10mins
With concurrent ECG monitoring
Infusion of calcium (100mls of 10% calcium gluconate in 1l of 0.9% saline at 50ml/hr
IV magnesium is essential if Mg2+ low
Stop causative agents including drugs
Mild/chronic
Oral calcium replacement +/- Vitamin D
Ensure magnesium levels adequate
