Clinical Calcium Homeostasis Flashcards
What are the dietary sources of calcium?
Dairy Green leafy vegetables Soya beans Tofu Nuts Bread/anything made with fortified flour Fish where you eat the bones
What are the functions of calcium/
Bone formation
Cell division and growth
Muscle contraction
Neurotransmitter release
What are the sources of vitamin D?
Sunlight Oily fish Eggs Foritified fat spreads Fortified breakfast cereals
What groups are at risk of vitamin D deficiency?
Children
Pregnant women
People of colour
People who spend a lot of tine indoors ie nursing home residents
People who cover themselves up a lot ie Burkha
What is the numerical definition of hypocalcaemia?
Serum calcium <2.20
What are the clinical features of acute hypocalcaemia?
Neuromuscular irritability: -Paraesthesia -Muscle twitching -Carpopedal spasm -Trousseau's sign -Chovstek's sign -Seizures -Laryngospasm -Bronchospasm Cardiac: -Prolonged GT interval -Hypotension -Heart failure -Arrhythmia Papilloedema
What are the clinical features of chronic hypocalcaemia?
Ectopic calcification Extrapyramidal signs Parkinsonism Dementia Subcapsular cataracts Abnormal dentition Dry skin
What are the causes of hypocalcaemia?
Disruption of parathyroid gland (total thyroidectomy) Selective parathyroidectomy Severe vitamin D deficiency Magnesium deficiency Cytotoxic drugs Pancreatitis, rhabdomyolysis and large volume blood transfusions Hypoparathyroidism Secondary hyperparathyroidism Drugs
What history features would be suggestive of hypocalcaemia?
Reduced calcium or vitamin D intake Neck surgery Autoimmune disorders Medications Family history
What investigations are useful in hypocalcaemia?
ECG Serum calcium Albumin Phosphate PTH U&Es Vitamin D Magnesium
What are the causes of hypoparathyroidism?
Agenesis Destruction Infiltration Reduced secretion of PTH Resistance to PTH
What are the characteristics of pseudohypoparathyroidism?
Presents in childhood
Group of heterogenous disorders defined by kidney and bone unresponsiveness to PTH.
Characterised by hypocalcaemia, hyperphosphatemia and elevated PTH concentrations
How is mild hypocalcaemia defined and treated?
Asymptomatic and >1.9mmol/L serum calcium
Commence oral calcium tablets
If post thyroidectomy repeat calcium 24hrs later
is vitamin D deficient, start vitamin D
If low Mg, stop any precipitating drug and replace Mg
How is severe hypocalcaemia defined and treated?
Symptomatic or <1.9mmol/L serum calcium MEDICAL EMERGENCY Administer IV calcium gluconate Initial bolus of calcium gluconate followed by infusion Treat the underlying cause
What are the causes of hypercalcemia?
Primary hyperparathyroidism Hypercalcaemia of malignancy Familial hypocalciuric hypercalcaemia Tertiary hyperparathyroidism Vitamin D intoxication Chronic granulomatous disorders Medications
What are the clinical features of hypercalcaemia?
Renal: -Polyuria -Polydipsia -Nephrolithiasis Gastrointestinal: -Anorexia -Nausea and vomiting -Constipation Musculoskeletal: -Muscle weakness -Bone pain Neurological: -Decreased concentration Cardiovascular: -Shortening QT interval "Bones, stones, groans and psychic moans"
What signs on history and examination are suggestive of hypercalcaemia?
History: -Symptoms of hypercalcaemia -Systemic enquiry -Medications -Family history Examination: -Lymph nodes -Concerns about malignancy
What investigations can be useful in hypercalcaemia?
U&Es Serum calcium PO4 Alk phosphate Myeloma screen Serum ACE PTH Consider ECG
How is primary hyperparathyroidism investigated?
Serum calcium PTH U&Es Abdominal imaging for renal calculi DEXA for osteoporosis 24 hour urine collection for calcium Vitamin D
When is parathyroid surgery indicated?
Presence of symptoms of hypercalcaemia Serum calcium >0.25mmol/L above the upper limit of normal Osteoporosis on DEXA eDFR <60 Presence of kidney stones <50 years of age
How is primary hyperparathyroidism managed medically?
Generous fluid intake
Cinacalcet
What are the characteristics of familial hypocalciuric hypercalcaemia?
Autosomal dominant disorder of the calcium sensing receptor
Benign- no therapy indicated
If positive family history then screen young family members
PTH can be normal or slightly elevated
What are the characteristics of multiple endocrine neoplasia type 1?
Presents as primary hyperparathyroidism with pancreatic and pituitary issues
Usually presents in the 2-4 decades of life
What are the characteristics of multiple endocrine neoplasia type 2?
Can present as medullary thyroid cancer, phaeochromocytoma or primary hyperparathyroidism
Usually milder disease than MEN 1
How is hypercalcaemia managed?
Rehydration- 0.9 saline 4-6 litres over 24 hours
After rehydration, intravenous bisphosphonates- zolendronic acid 4mg over 15 mins
What is the second line management of hypercalcaemia?
Glucocorticoids, calcitonin, calcimimetics and parathyroidectomy
