Calcium metabolism and disorders Flashcards
what does vitamin d increase
calcium phosphorylation absorption from the gut
main stimulus of PTH production
low ca2+
main stimulus of calcitonin production
high ca2+
calcitonin effects on bone
inhibits osteoclast resorption
thereby lowers ca and po4
calcium sensing receptor
g protein coupled receptor that plays a role i regulation of extracellular calcium homeostasis
hypercalcaemia features
bones
stones
abdominal groans
psychic moas
chronic hypercalcaemia features
Myopathy
Fractures
Osteopaenia
Depression
Hypertension
Pancreatitis
DU
Renal calculi
acute hypercalcaemia features
Thirst
Dehydration
Confusion
Polyuria
causes of hypercalcaemia
primary hyperparathyroidism= main cause
2nd is malignancy
3rd is drugs
Drugs: Vit D, thiazides
Granulomatous Disease eg Sarcoid, TB
Familial Hypocalciuric Hypercalcaemia
High turnover: bedridden, thyrotoxic, Pagets
Others
Tertiary hyperparathyroidism
what to think in supressed PTH
malignancy
diagnosis of primary hyperparathyroidism
raised serum calcium
raised serum PTH
increased urine calcium excretion
diagnosis of hypercalcaemia of malignancy
Raised calcium and alkaline phosphatase
X-ray, CT, MRI, PET
Isotope Bone Scan
mechanisms of hypercalcaemia of malignancy
Metastatic Bone destruction
PTHrp from solid tumours
Osteoclast activating factors
management of acute hypercalcaemia
0.9& saline
Consider loop diuretics once rehydrated- avoid thiazides
Bisphosphonates- single dose will lower Ca over 2-3d, maximum effect at 1 week
Steroids occasionally used e.g Pred 40-60mg/day for sarcoidosis
calcium mimetic
tricks calcium sensing recpeotr into thinking lots of calcium there so suppresses pth = cinacalcet
management of primary hyperparathyroidism if unfit for surgery
cinacalcet
indications for parathyroidectomy
end organ disease
very high calcium >2.85
under 50
egfr <60
Hypocalciuric Hypercalcaemia
elevated calcium in blood but low in urine
often due to inherited disorder
management of acute hypocalcaemia
Emergency: IV calcium gluconate 10 ml, 10% over 10 mins (in 50ml saline or dextrose)
Infusion (10ml 10% in 100 ml infusate, at 50 ml/h)
causes of hypomagnasaemia
Alcohol
Drugs
Thiazide
PPI
GI illness
Pancreatitis
Malabsorption
pseudohypoparathyroidism
rare inherited disorder that results in the body’s inability to respond properly toparathyroid hormone (PTH), leading to abnormalities in calcium and phosphate levels
