Hypocalcaemia Flashcards
What causes hypocalcaemia
decreased calcium entry into the circulation or increased loss of free calcium from the circulator
What are some causes of decreased calcium entry into the circulation
Vitamin D deficiency
Hypoparathyroidism
pseudohypoparathyroidism
What are some causes of extravascular calcium deposition
Rhabdomyolysis and tumour lysis syndrome
Acute pancreatitis
Widespread osteoblastic metastases
Hungry bone syndrome
What are some causes of increased intravascular calcium binding
acute respiratory alkalosis
Massive blood transfusion
Foscarnet
What can be associated with hypocalcaemia due to impaired secretion of both PTH and calcitrol
Sepsis
What are some causes of vitamin D deficiency
lack of sun exposure
poor intake or malabsorption (coeliac disease)
Liver failure
Chronic kidney disease
Impaired activation of Vitamin D due to mutations in the 1alpha - hydrolyse gene
Target organ resistance due to mutations in the vitamin D receptor gene
What are some causes of hypoparathyroidism
post thyroid or parathyroid surgery autoimmune Infiltrative disease of the parathyroid glands: Wilson'd, haemochromatosis Congenital: DiGeorge syndrome Hypomagensaemia HIV infection
What MSK problems could be a sign of hypocalcaemia
Tetany
muscle spasms/ cramps
paraesthesia
myopathy
Ckvostek’s sign (tapping the facial nerve in front of the ear causes contraction of the facial muscles ipsilaterally)
Trousseau’s sign: inflating the blood pressure cuff to above systolic BP causes carpal spasm
What are some neuropsychiatric / eye problems that could be a sign of hypocalcaemia
Seizures, fatigue, depression, anxiety
movement disorders: dystonia, hemiballismus, basal ganglia calcifications
Eyes: cataracts, papilloedema with severe hypocalcaemia
What are some cardiac signs of hypocalcaemia
Cardiac failure
hypotension
prolonged QT interval
decreased digoxin effect
What are some GI symptoms of hypocalcaemia
Reduced gastric acid secretion
steatorrhoea
What are some skin symptoms of hypocalcaemia
Dry and coarse skin and hair
brittle nails
What is pseudohypoparathyroidism characterised by
PTH resistance usually caused by mutations in the GNAS gene) resulting in an inability of PTH to activate adenylate cyclase
Describe some phenotypic characteristics of type 1a disease (maternal)
short stature obesity round face short fourth/ fifth metacarpals subcutaneous calcification occasionally mental retardation
they also have hypocalcaemia
Describe the difference between maternally inherited and paternally inherited mutations in type 1a
Paternally have the same phenotypic abnormalities but have normal serum calcium levels
What is type 1b pseudohypoparathyroidism characterised by
hpocalcaemia but not the phenotypic abnormalities
What makes up Albright’s hereditary osteodystrophy (AHO)
short stature
obesity
round face
short fourth and fifth metacarpals
What are some useful tests in determining the cause of hypocalcaemia
serum phosphate magnesium alkaline phosphatase creatinine alanine transaminase coeliac screen intact PTH
Describe the levels of phosphate and PTH in hypoparathyroidism
Phosphate levels may be normal or high
PTH is low
Describe the levels of the following in vitamin D deficiency serum phosphate
urinary calcium exceretion
bone specific alkaline phosphatase
PTH
serum phosphate: low or normal
urinary calcium exceretion : low
bone specific alkaline phosphatase: elevated
PTH: raised
What is the treatment for patients with an adjusted total calcium of more than 1.9mmol/L
usually asymptomatic but can be treated by increasing dietary calcium intake
What should be given for patients with tetany, seizures, ECG changes and reduced cardiac function
IV calcium
Why is calcium gluconate preferred over calcium chloride
it causes less local tissue necrosis
How is calcium gluconate given
10ml 10% infused over 10-20 minutes with cardiac monitoring
How should concomitant hypomagnesaemia be corrected
with IV magnesium sulphate
What is the preferred preparation of Vitamin D for patients with severe acute hypocalcaemia and why
Calcitriol
It has a rapid onset of action
What should the total serum calcium measurement always be adjusted for
albumin levels
What is the ultimate goal of treatment in chronic hypocalcaemia
Maintain serum calcium in the low-normal range without causing hypercalciuria
