CKD-Metabolic bone disease Flashcards
How does CKD lead to secondary hyperparathyroidism
An imbalance in phosphorous due to reduced kidney function leads to increase work done by the parathyroid
What are the three receptors that influence how the parathyroid gland functions, which is the main regulator, what also influences the gland
Ca-sensing receptor (CaSR), vitamin D-receptor (VDR), FGF-23/ Ca-SR, phosphate
What is the main goal for PTH,
maintaining calcium levels
How does PTH affect the kidney
increases renal absorption of calcium, increases renal excretion of phosphorous, stimulates synthesis of calcitriol
How does PTH affect the intestine
Indirectly increases absorption on calcium and phosphorous in the small intestine
How does PTH affect bone
stimulates osteoclasts to resorb bone, inhibits osteoblasts and bone formation
What will trigger increases in PTH
decreased serum calcium levels, decreased production of calcitriol, increased serum phsopshorous (indirect)
What happens to phosphorous and calcitrol in nephron loss and how do these changes affect calcium
Phosphorous increases and binds calcium lowering serum calcium, calcitriol levels decrease lowering calcium levels
T/F: When PTH is activated there is an increase in phosphorous and calcium due to bone breakdown and absorbtion in the intestines BUT the kidney tries to remove phosphorus while reabsorbing calclium
True
T/F: Calcitriol is inactivated Vitamin-D
False: Calcitriol is activated vitamin D
What does FGF-23 do, where is it made
inhibit PTH production, suppress the hormone that creates calcitriol (1-alpha-hydroxylase)/osteocytes
What are consequences of hyperparathyroidism
osteoporosis, vasuclar calcification, cardiovascular issue, anema
What are the four bone diseases that can occur with CKD
ostetitis fibrosa cystica, adynamic bone disease, mixed uremic bone disease, osteomalacia
What usually causes ostetitis fibrosa cystica, what happens
Constantly elevated PTH, accelerated bone formation and resorption that does not allow for proper mineralization increasing the number of osteoid
T/F: Adynamic bone disease is characterized by low turnover bone state and is usually caused by oversupressing PTH through medications
True
When there is high calcium and low PTH levels this may be a sign of what bone disease, what is the level of PTH
Adynamic Bone disease, less than 150
What stage of CKD does calcification of blood vessels, heart valves and skin become frequent
Stage 5
What are the ranges for phosphorous in patients with CKD for stages 3,4,5
2.7-4.6, 2.7-4.6, 3.5-5.5
What are the ranges for corrected calcium in patients with CKD for stages 3,4,5
8.4-10.2, 8.4-10.2, 8.4-9.5
What are the ranges for PTH for corrected calcium in patients with CKD for stages 3,4,5
35-70, 70-110, 150-300
How is phosphorous excreted when the kidney can no longer excrete it
phosphrous binders bind it and it leaves through the stool
If phosphorous binders are to work what must be the dietary phopshorous consumed per day
800-1000mg
What are the phosphorous binders
calcium based (Tums), sevelamer ( Renevela and Renagel), lanthanum carbonate, iron based (Auryxia and Velphro
Why are are calcium based phosphorous binders not ideal
increase the risk of calcification
T/F: It is better to take phosphorous binders on an empty stomach to reduce side effects
False: Phosphorous binders must be taken with food so that the drugs have something to bind too
When can lanthanum carbonate be taken
With or after meals
Which phosphorous binder should not be used in iron overload, which has low iron absorption
Ferric citrate (Auryxia), sucroferric oxyhydroxide (Velphoro)
When should vitamin D or a vitamin D analog be given
If the calcium is less than 9.5 and phosphorous is less than 5.5
What are the vitamin D analogs (calcimimetic)
calcitriol, doxercalciferol, and paricalcitol
What are the comparable dose of the vitamin D analogs
1 mcg (calcitriol), 2mcg (doxercalciferol), 4 mcg (paricalcitol)
When is Aluminum used as a phosphorous binder, how long can it be used
Emergency situations where the phosphorous is greater than 7, no longer than 4 weeks
What range of PTH would cause the dose of vitamin D and vitamin D analogs to be lessened
less than 150
Which of the vitamin D analogs causes the most hypercalcemia and hyperphosphatemia, which is the pro drug that is less hypercalcemic, which is the least hypercalcemic and hyperphosphatemic
calcitrol, doxercalciferol, paricalcitol
What are the two calcimimetics
cinacalet and etelcalcetide
What is the MOA of cinacalcet (sensipar)
reduce PTH by increasing sensitivity of the calcium receptor on the parathyroid gland
What must the corrected calcium be before initiating cinacalcet
greater than 8.4
What is the MOA of Etelcalcetide
binds to the calcium receptor on the partathryroid and enhance its activation by extracellular calcium
Which of the calcimimetics is only for hemodialysis
Etelcalcetide
What is the safest way to transition cincalcet to etelcalcetide
Discontinue cincalcet for 7 days prior to starting etecalcetide
T/F: Vitamin D analogs only increase calcium
False: Vitamin D analogs increase calcium and phosphorous (phosphorous increased through gut absorption)
