PTH Flashcards
Actions of PTH (4)
Release Ca form bone, Reabsorb Ca in kidneys, Absorb C and P in small intestine, synthesize Vit D
Phosphate excretion increased by..
PTH, PTHrP, hypercalcemia, hypokalemia, hypoagnesemia, calcitonin, glucocorticoids, diuretics
Actions of Vitamin D
Increases intestinal absorption of calcium and stimulates osteoclasts
Labs for PTH (Ca, PTH, P, urine Ca)
High Ca, elevated or normal PTH, low phosphorus, elevated urine Ca
Tx of primary hyperPTH
hydration, ambulation, moderate Ca intake, bisphosphonates, calcimimetics (alters calcium sensing receptor)
Tx of hypercalcemia
increase fluid intake, moderate Ca diet, bisphosphonates, calcitonin, corticosteroids
Mechanism of action: Bisphosphonates
inhibit osteoclastic bone resorption
Types of bisphosphonates (5)
Pamidronate, zoledronic acid, alendronate, risedronate, ibandronate
Mechanism of action: Calcitonin
Increases urinary calcium excretion, inhibits bones resorption; normally secreted by C cells of thyroid
SE’s of Calcitonin
Tachphylaxis
Labs for secondary hyperPTH
low Ca, high Ph, high PTH, low VitD
Tx of secondary hyperPTH
Low Ph diet, Ph binders, VitD replacement
Labs in renal failure induced hypocalcemia
Low Ca, high Ph, PTH and Cr
Phosphate binders (3)
calcium carbonate, calcium acetate, sevelamer
VitD replacements (3)
calcitriol, paracalcitol, doxercalciferol
Labs in hypoPTHism
low calcium, low PTH, high Ph
Tx goals of hypoPTHism
normalize Ca and Ph, avoid hyperCa
Tx for osteoporosis
Bisphosphonates (Alendronate, risedronate, ibandronate), Selective estrogen receptor modulates (Raloxifene), Calcitonin (not used anymore), Teriparatide, Denosumab
Raloxifene
SERM used to tx osteoporosis
SE’s of bisphosphonates
GI irritation, administration restrictions
Teriparatide
PTH analog. Exposure of short daily bursts stimulates bone resorption and formation; Used to tx osteoporosis. SEs: dizziness, palpitations, transient hypercalcemia
Denosumab
RANKL inhibitor
Does OPG increase or decrease bone resorption?
Decrease
Which decreases Ca bound to albumin (and therefore increases free ionized Ca): Alkalosis or Acidosis
Acidosis
MC sites of Ca reabsorption in kidneys
PT and loop of Henle
Resorption of renal Ca is enhanced by…
PTH, phosphate, metabolic alkalosis, thiazide diuretics, increased Na resorption
Excretion of renal Ca is enhanced by…
metabolic acidosis, loop diuretics, saline diuresis and PTH deficiency
Renal reabsorption of Ph is enhanced by…
phosphate depletion, hyPOparathyroidism, hyPOcalcemia
Renal excretion of Ph is enhanced by…
PTH, PTHrP, hypercalcemia, hypokalemia, hypomagnesemia, glucocorticoids, calcitonin and diuretics
Triad of Multiple Myeloma
Hypercalcemia, anemia, renal insufficiency
Causes if secondary hyperparathyroidism
phosphate retention and lack of 1-a-hydroxylase activity in failing kidneys