calcium homeostasis Flashcards
what is the recommended daily calcium intake for men, women, osteoporosis, and growing skeleton
men - 450mg
women - 350mg
osteoporosis - 1500mg
growing skeleton - 750mg
how much calcium is stored in the body?
1kg in bone
10mg/l in ecf
how is calcium stored in bone
hydroxyapetite
what is the formula for adjusted calcium
adjusted Ca= total Ca + 0.02(40-[albumin])
what is the effect on calcium binding to proteins?
acidosis (more Ca2+ ions) decreases binding
alkylosis (more CaPr) increases binding
what 4 things regulate plasma calcium?
binding to proteins PO4
parathyroid hormone
vitamin D
calcitonin
what is the response to decreased calcium
calcitonin decreases removing inhibitory effect on osteoclasts
calcium sensing receptor increases PTH synthesis
released from parathyroid gland chief cells
how does PTH act?
promotes calcium reabsorption via kidney
stimulates osteoclast resorption of bone releasing Ca
drives 1.25 (OH)2 production in kidney - more Ca reabsorption in gut
how does PTH act?
promotes calcium reabsorption via kidney
stimulates osteoclast resorption of bone releasing Ca
drives 1.25 (OH)2 production in kidney - more Ca reabsorption in gut
how do calcium sensing receptors work
Ca binds to trans-membrane receptor
acts as antagonist decreasing PTH release
when calcium is low in presence of Mg, PTH is released and fuses with cell membrane
commonest defect in calcium sensing receptors
Familial Benign Hypercalcaemic Hypocalciuria
what does MCSF and RANKL result in
osteoclastogenesis
how much ACa is hypercalcaemia?
ACa>2.6 mmol/L
how much ACa is hypocalcaemia
ACa<2.2 mmol/L
9 symptoms of hypercalcaemia
nausea
peptic ulcers
constipation
soft tissue calcification
mental disturbances
depression
renal failure
renal stones
polyuria
