z- minerals and bone metabolism (ch-38)

Calcium Functions
Calmodulin (made up of 4 Ca2+ ions) – it activates adenylate cyclase and phosphodiesterase
Calcium binds to a protein to form Troponin – found in cardiac muscle
Cell communication
Controls endocrine gland secretion
Needed for blood coagulation
Calmodulin
(made up of 4 Ca2+ ions) – it activates adenylate cyclase and phosphodiesterase
Phosphate Function
Part of the cell membrane structure
Energy
Gene Replication
Regulation of Calcium & Phosphate
Parathyroid Hormone
Calcitronin
Vitamin D
Calcitronin
Opposite of PTH
Produced by C-cell of PT gland
Net effect:
v Ca2+
^ Phosphate
Hypercalcemia: stimulates release
Hypocalcemia: inhibits release
Vitamin D
Stimulates membrane transport of Ca2+ b/t cells
Primary Hyperparathyroidism
leads to hypercalcemia/hypophosphatemia > hypercalciuria > urolithiasis/nephrocalcinosis (kidney stones)
Hyperphosphatemia
rare, genetic
Leads to renal osteodystrophy (ROD)
No renal excretion of phosphate
Hypophosphatemia
rare, genetic, X-linked
Defect in renal absorption of phosphate
^ excretion of phosphate in urine
Hypoparathyroidism
deficency in PTH caused by infection or parathyroidectomy
Pseudohypoparathyroid
PTH level is normal or high means that there is a receptor problem
Effect of Hypercalcemia on Calcitronin
stimulates release
Effect of Hypocalcemia on Calcitronin
inhibits release
EDTA and Calcium
cannot use because of chelation
Heparin and Calcium
no interference
Citrate/Lactate and Calcium
can bind to free calcium to make ligands
falsely decreased result for an ionized calcium test
they are ok for total calcium tests
Acidosis
favors disassociation of Ca2+ from ligands and proteins
Alkalosis
favor association of Ca2+ from free Ca2+ to proteins and ligands
Calcium and Protein
form Troponin – found in cardiac muscle
Regulation of Calcium & Phosphate
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Total Calcium
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