Hyper/Hypocalcaemia Flashcards
what is hypercalcaemia
serum calcium > 2.6mmol/L
what are the 2 main causes of hypercalcaemia
- primary hyperparathyroidism: commonest cause in non-hospitalised patients
- malignancy: commonest cause in hospitalised pt (may be due to PTHrP from tumour, bone mets, myeloma)
what are other causes of hypercalcaemia
- sarcoidosis
- vitamin D intoxication
- acromegaly
- thyrotoxicosis
- milk-alkali syndrome
- paget’s disease
- addison’s
- dehydration
what diagnosis must be excluded in all cases of hypercalcaemia where PTH is suppressed
malignancy!
what are the symptoms of hypercalcaemia
stones, bones, moans, groans
- kidney stones
- painful bones
- abdo: constipation, N&V
- psychiatric: fatigue, depression, psychosis
how might severe metabolic parathyroid bone disease present on x-ray
classic cystic appearance (Brown tumours)
what might renal USS in hypercalcaemia show
nephrocalcinosis
what is familial hypocalciuric hypercalcaemia (FHH)
- rare condition caused by genetic defect in calcium sensing receptor
- distinguished from primary hyperparathyroidism by demonstration of a low urine calcium/creatinine ratio
- usually a family history of mild hypercalcaemia
what should happen if parathyroid surgery for adenoma is planned
adenoma should be visualised but may be difficult if lesion is small
when should surgical treatment of hyperparathyroidism be considered
if serum calcium > 2.85 mmol/L or if symptoms are debilitating
- young pt and those w severe acute hypercalcaemia are also usually recommneded for surgery
in patients where surgical treatment of hyperparathyroidism is not desirable, what is an alternative option
calcimimetic drugs e.g. cinacalcet effective at lowering calcium
at what value does symptomatic hypocalcaemia occur
when serum calcium < 1.9 mmol/L
what is the commonest cause of hypocalcaemia
post surgical hypoparathyroidism following thyroidectomy
- often temporary but may be permanent due to damage or inadvertent removal of PTH glands
what are other causes of hypocalcaemia (2)
- severe vitamin D deficiency: consider in high risk groups
- hypomagnesaemia: function hypoparathyroidism with normal/low PTH levels
how might severe vitamin D deficiency present in neonates
seizures and tetany due to hypocalcaemia
what are phosphate levels in vitamin D deficiency
low due to elevated PTH levels
what are common causes of hypomagnesaemia
- GI loss
- alcohol
- drugs e.g. PPIs
what may acute severe hypocalcaemia cause (3)
- laryngospasm
- prolonged QT interval
- seizures
how might hypocalcaemia present
- muscle cramps
- carpo-pedal spasm
- peri-oral and peripheral paraesthesia
- neuro-psychiatric symptoms
what 2 clinical signs are associated with hypocalcaemia
- positive Chvostek’s sign (facial spasm when cheek is tapped gently with finger)
- Trousseau’s sign: carpo-pedal spasm induced after inflation of sphygmomanometer
what is the mainstay of treatment of hypocalcaemia
calcium replacement
how should patients with severe vitamin D deficiency be treated
loading dose of cholecalciferol
- 20,000 IU per week is given for 7 weeks followed by a maintenance dose of 1-2000 IU per week
how is hypoparathyroidism treated
alfacalcidol or calcitriol
- typical starting dose is 0.25 mcg/day 1-alfacalcidol, with dose titration according to clinical and biochemical response
Oral calcium supplements, e.g Sandocal and Adcal D3, are given in combination with alfa-calcidol
how is acute magnesium deficiency treated
precipitating drugs stopped and IV Mg replacement started
- usually given as MgSO4 24mmol/24hrs
what is pseudo-hypoparathyroidism
rare condition caused by a mutation in a G protein coupled to the PTH receptor and leads to PTH resistance
what is pseudo-hypoparathyroidism characterised by
hypocalcaemia and high phosphate which would usually = hypoparathyroidism BUT high PTH and normal vitamin D = PTH resistance rather than deficiency
how might patients with pseduo-hypoparathyroidism present
short stature
round face
short 4th/5th mets
