Term
what are the primary regulators of calcium and phosphate homeostasis? |
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Definition
PTH and vitamin D
calcitonin, glucocorticoids, and estrogens play secondary roles |
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Term
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Definition
acts on membrane G-protein-coupled receptors to increase cAMP in bone and renal tubular cells
in kidney: inhibits excretion of Ca2+, promotes PO4 excretion; stimulates production of active vitamin D metabolites
in bone: promotes bone turnover by increasing activity of osteoclasts and osteoblasts (osteoclast indirectly activated by PTH via osteoblast formation of RANK ligand (RANKL) - part of TNF cytokine family)
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Term
PTH at continuously high levels (such as secondary hyperparathyroidism) |
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Definition
leads to increased bone resporption, hypercalcemia (initially), and hyperphosphatemia |
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Term
low intermittent doses of PTH produce . . . |
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Definition
a net increase in bone formation - basis of use of teriparatide, a recombinant truncated form of PTH, for IV tx of osteoporosis |
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Term
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Definition
synthesis and secretion of PTH is primarily regulated by the serum concentration of free ionized calcium - drop in free ionized calcium stimulates PTH release
secondary Vitamin D metabolites play secondary role --> inhibit PTH synthesis |
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Term
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Definition
recombinate truncated form of PTH
given IV for tx of osteoporosis |
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Term
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Definition
- - fat soluble vitamin
- - active metabolites are formed in the liver and kidney:
* 25-hydroxyvitamin D
* calcifediol
* 1,25-dihydroxyvitamin D (calcitriol)
- - Renal synthesis of active metabolites of Vit D stimulated by PTH and FGF23 (produced by osteoclasts and osteoblasts)
- active Vit D metabolites cause net increase in serum concentrations of calcium and phosphate by increasing intestinal absorption and bone resorption and decreasing renal excretion
- inhibits PTH secretion DIRECTLY and INDIRECTLY (by increasing serum Ca)
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Term
where does Vit. D have a greater effect: kidney or GI tract? |
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Definition
greater effect on GI tract and bone than kidney |
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Term
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Definition
Vit D required for normal bone mineralization
= Ricket's in kids
= osteomalacia in adults |
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Term
what is Vitamin D used to treat? |
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Definition
deficiency states
intstinal osteodystrophy
chronic kidney or liver dz
hypoparathyroidism
nephrotic syndrome
also used in combination with calcium supplementation (prevent and treat osteoporosis in older women)
topical formation for psoriasis
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Term
cholecalciferol and ergocalciferol |
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Definition
2 forms of Vitamin D
available as oral supplements
commonly added to dairy products and other foods |
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Term
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Definition
active form of Vitamin D
required in patients with conditions that impair vitamin D activation (chronic kidney dz, liver dz, hypoparathyroidism)
in chronic kidney dz, calcitriol reduces PTH levels, corrects hypocalcemia, and improves bone disease, but it can also result in hypercalcemia and hypercaliuria through direct effects on intestinal, bone, and renal handling of calcium and phosphate |
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Term
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Definition
prodrug that is converted in the liver to 1,25-dihyrdroxyvitain D
causes less hypercalcemia and less hypercalciuria than calcitriol
used in tx of secondary hyperparathyroism due to chronic renal dz |
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Term
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Definition
19-nor-1,25-dihydroxyvitamin D2
analog of calcitriol
causes less hypercalcemia and less hypercalciuria than calcitriol
approved for tx of 2ary hyperparathyroidism due to chronic renal dz |
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Term
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Definition
analog of calcitriol
causes less hypercalcemia and less hypercalciuria than calcitriol
used for tx of psoriasis |
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Term
toxicity of Vitamin D or its active metabolites |
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Definition
hypercalcemia
hyperphosphatemia
hypercalciuria |
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Term
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Definition
secreted by the thyroid gland
decreases serum calcium and phosphate by inhibiting bone resorption and inhibiting renal excretion of these minerals
bone formation is ultimately reduced
USE: in conditions where an actue reduction of serum calcium is needed (ex: Paget's dz and hypercalcemia)
also approved for tx of osteoporosis (but not as effective)
salmon calcitonin used because has longer half-life and greater potency
admin = injection or nasal spray |
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Term
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Definition
selective estrogen receptor modulators (SERMs)
prevent or delay bone loss in postmenopausal women
inhibition of PTH-stimulated bone resorption |
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Term
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Definition
inhibit bone mineral maintenance = chronic systemic use is common cause of osteoporosis in adults
but they are useful in intermediate-term tx of hypercalcemia |
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Term
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Definition
(alendronate, etidronate, ibandronate, pamidronate, risedronate, tiludronate, and zoledronic acid)
short-chain organic polyphosphate compounds that reduce both the resorption and the formation of bone by an action on the baasic hydroxyapatite crystal structure
effects on vit. D production and calcium absorptions from GI tract
direct effects on osteoclasts
used to manage hyper calcemia associated with some malignancies and to treat Paget's dz
chronic uses of this for osteoporosis tx (increases bone density and reduces fractures) |
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Term
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Definition
calcimimetics
lowers PTH by activating the calcium-sensing receptor in parathyroid gland
oral tx for secondary hyperparathyroidism in chronic kidney dz
tx for hypercalcemia in pts with parathyroid carcinoma -
toxicities include hypocalcemia and adynamic bone dz (profound decr. bone cell activity) |
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Term
which diuretics affect serum and urinary calcium levels |
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Definition
thiazide diuretics and furosemide |
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Term
1,25-dihydroxyvitamin D3 would do what on intesinal absorption of Ca and PO4-??? |
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Definition
would increase absorption of both |
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Term
what would you give to a man with calcium-containing renal stones: Lasix or HCTZ? |
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Definition
hydrochlorothiazide (HCTZ) |
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Term
where does cinacalcet act to decr. PTH secretion? |
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Definition
acts by activating calcium-sensing receptors |
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Term
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Definition
decreases bone resorption by binding RANKL and preventing its effects on osteoclasts/osteoclas precursors |
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Term
alendronate is an analog of what? |
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Definition
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