hypocalcaemia Flashcards
when does symptomatic hypocalcaemia occour?
when serum calcium is <1.9 mmol/L, or at higher values if there is a rapid drop in calcium
what are the commonest causes of hypocalcaemia?
post surgical hypoparathyroidism following thyroidectomy is the commonest cause
usually temporary but may be permanent if parathyroid glands are damaged/inadvertently removed.
long term followup is needed to asses if there is recovery of parathyroid function
what are the consequences of hypomagnesaemia in relation to hypocalcaemia?
causes functional hypoparathyroidism with normal or low PTH levels
what is hypomagnesaemia and what can cause it ?
low magnesium in the blood
causes include
- GI loss
- alcohol
- drugs, especially PPI
what are the clinical features of acute severe hypocalcaemia?
acute severe hypocalcaemia can cause
- laryngospasm
- prolonged QT interval
- seizures
it is a medical emergency
what are the clinical features of hypocalcaemia?
- muscle cramps
- carpo pedal spasm
- peri oral and peripheral paraesthesia
- neuropsychiatric symptoms
- pins and needles
- convulsions
- paralysis
- patients may have positive Chvostek’s sign (facial spasm when the cheek is tapped gently with the finger)
- may have positive Trousseau’s sign (carpo - pedal spasm induced after inflation of sphygmomanometer)
how is hypocalcaemia treated?
- calcium replacement e.g sandal and Adcal D3 are given with alfa calcidol. keep Ca levels at lower end of range to reduce risk of nephrology calcinosis
- vit D deficient = give loading dose of Cholecalciferol for 7 weeks followed by a maintenence dose
- hypoparathyroidism is treated with 1- alfacalcidol or calcitriol
how should hypomagnesaemia be treated?
in an acute situation, stop precipitating drugs and give IV replacement as MgSO4 23mmol/24hrs
if GI loss/alcohol is the cause, get specialist input to prevent recurrence.
how does severe vit D deficiency present in a neonate?
tetany
seizures
How can vitamin D deficiency cause hypocalcaemia?
the active metabolite form of vitamin D, Calcitriol, used for calcium absorption from the digestive tract and reabsorption of Ca from the bones and kidneys into the blood stream
Low vit D = this is unable to occur
typically phosphate is low due to elevated PTH levels, unlike in hypoparathyroidism where phosphate is high
severe vit D deficiency causes hypocalcaemia and should be considered in high risk groups
what is pseudo hypoparathyroidism?
rare condition
caused by mutation in G protein coupled to PTH receptor, so causes PTH resistance
charecterised by hypocalcaemia and high phosphate, high PTH and normal fit D suggests PTH resistance rather than deficiency.
patients may have syndromic appearance with short stature, round face and short 4th and 5th metacarpals.
