Calcium disorders Flashcards
Causes of hypercalcaemia
Primary hyperparathyroidism - usually asymptomatic
Malignancy - rapid onset, severe, symptomatic e.g. with breast, lung, oesophageal, head and neck, skin, cervix, breast, kidney and bladder cancer
Drugs - thiazide diuretics, lithium, vitamin D, vitamin A, calcium with antacids, calcium with vit D
Granulomatous diseases - sarcoidosis, TB
Renal - CKD (secondary hyperparathyroidism), treatment with calcium and vit D, recovery phase from AKI
Familial hypocalciuric hypercalcaemia
Endocrine - thyrotoxicosis, Addison’s disease, Phaeochromocytoma, vasoactive intestinal polypeptide hormone-producing tumour
Paget’s disease due to immobilisation
Two most common causes of hypercalcaemia
Primary hyperparathyroidism
Malignancy
Primary hyperparathyroidism - what is it?
Excessive and inappropriate secretion of parathyroid hormone (PTH) secreted by the parathyroid glands
This increases bone resorption and renal calcium reabsorption and intestinal calcium absorption
–> high calcium
Causes of primary hyperparathyroidism
Solitary parathyroid adenoma (85%) Multiglandular parathyroid hyperplasia Ectopic parathyroid adenomas Parathyroid cancer Multiple endocrine neoplasia type 1 and type 2A Hyperparathyroidism jaw tumour syndrome Familial isolated hyperparathyroidism
Mechanisms of malignancy causing high calcium
In 80% = secretion of PTH-related protein and other circulating factors by the tumour (a paraneoplastic syndrome)
In 20% bone metastases cause osteolysis and release of skeletal calcium, for example in breast cancer and multiple myeloma.
Features of hypercalcaemia
Bones - e.g. bone pain, osteoporosis
Stones - renal stones, nephrogenic diabetes insipidus
Groans - nausea, vomiting, consipation, abdo pain
Psychic moans - depression, anxiety, psychosis
Plus:
Drowsy, fatigue, muscle weakness, confusion
Shortened QT interval on ECG
Hypertension
Investigations for hypercalcaemia
Serum calcium blood test
FBC - to diagnose haem malignancy or anaemia of chronic disease
ESR or CRP - increased in malignancy, inflamm conditions, granulomatous conditions
eGFR and creatinine - hydration, CKD, AKI
Serum and urine protein electrophoresis, inc urine Bence-Jones protein — for myeloma.
LFTs - to exclude liver mets or chronic liver failure; ALP may be increased in primary hyperparathyroidism, Paget’s disease, myeloma, or bone metastases
TFTs
PTH
Vitamin D
Serum cortisol
Urine ACR
CXR - to exclude lung cancer or mets, sarcoidosis etc
Management of hypercalcaemia
May need emergency hospital admission if severe
Rehydration with normal saline, typically 3-4 litres/day
IV bisphosphonates may be used, calcitonin, steroids in sarcoidosis
Furosemide may be used if can’t tolerate aggression fluid replacement
Explain secondary hyperparathyroidism
Reduced vit D or CKD causes reduced absorption of calcium from intestine, kidneys and bones causing low calcium.
This stimulates parathyroid glands to release more PTH. The parathyroid glands ungergo hyperplasia.
Explain tertiary hyperparathyroidism
Secondary hyperparathyroidism has been going on for a long time and causes autonomous PTH production.
Blood results in primary hyperparathyroidism
Increased PTH
Increased calcium
Low phosphate
Blood results in secondary hyperparathyroidism
Increased phosphate
Low vit D –> low or normal calcium –> increased PTH
Blood results in tertiary hyperparathyroidism
Increased PTH --> Increased or normal calcium Increased or normal phosphate Low or normal vitamin D Increased ALP
Features of hypocalcaemia
tetany: muscle twitching, cramping and spasm
perioral paraesthesia
if chronic: depression, cataracts
ECG: prolonged QT interval
What is Trousseau’s sign?
carpal spasm if the brachial artery occluded by inflating the blood pressure cuff and maintaining pressure above systolic
