Calcium Flashcards

Question

oxyphill cells of PT

Answer 1

Oxyphill-Unknown function; Recent reports of PTH production from C cells but not yet proven, its preliminary(not in texts yet).

Answer 2

Bone Kidneys --\> Gut

Answer 3

RANK + RANKL\ The osteoclast precursor has on it’s surface RANK and then the osteoblast has on it’s surface RANK-L. For that osteoclast to become activated and be able to breakdown bone – RANK has to combine with RANK-L. These have the meet, this differentiates and becomes a mature/active osteoclast. If RANK-L can’t combine with RANK because something is blocking it. OPG is called the decoy receptor. If there’s OPG (there’s always some around but if there’s more) it will combine with RANK-L and not allow RANK-L to combine with RANK and we won’t get our osteoclast.

Answer 4

**anabolic** **recombinant PTH** if high PTH all day = decrease bone BUT if pulsitile PTH - BUILD BONE! _use for 2 years only_ cell target = osteoblasts PTH binds to R - decreased apoptosis of osteoblasts, stim differentiation to osteoblasts secrete local regulatory factors

Answer 5

anti-resorptive inhibits release of cks that activate osteoclasts decreases RANKL, ? stimulates OPG It also decreases RANK-L and stimulates the OPG. So all of these things are going to affect that osteoclast and slow down breakdown. And we know that it decreases fracture risk in the hip and the spine. So if estrogen is indicated for other reasons, we know it’s a good bone drug and we know how it works. But the question normally is are we giving them estrogen for another reason. We use it less as a primary bone drug because of all of the other estrogen pros and cons.

Answer 6

PTH Vit D Calcitonin

Answer 7

familial disorder characterized by elevated PTH and end-organ resistance ## Footnote Both have the phenotype of pseudohypoparathyroidism, i.e. the genetic defect-Obesity, round face short metacarpals HOwever, Only daugther has the chemical abnormality, ie she is hypocalcemic- Not the mother Mother-Pseudopseudo; daughter is Pseudo.. Pseudo means PTH is not low, its actually high

Answer 8

cholecalciferol

Answer 9

calcium channel in luminal membrane of kidney cell distal tubule PTH stimulates the channel - major efffect of PTH

Answer 10

raloxifene like estrogen -- antiresorptive decreases fracture risk in the spin (no data in the hip) less good data, BAD after menobause because exacerbates symptoms

Answer 11

familial hypocalciuric hypercalcemia

Answer 12

inflammation can make 25 (OH) D3 into 1, 25 potential of 1(OH)ase

Answer 13

GI events allergy hypocalcemia (with IV zoledronic acid) renal issues (don't use in RF) musculoskeletal pain ONJ - rare!!

Answer 14

back/ms pain hypocalcemia (bigger problem) infections ONJ allergy \*\*atypical femoral fractures

Answer 15

DIRECT by Ca on PT chief cell ligand binds surface of cell at receptor and inhibits PTH high Ca --\> low PTH (don't need to conserve more!)

Answer 16

in excited muscle, Ca binds to tropoining, moves tropomyosin and exposes myosin binding sites on actin

Answer 17

endocrine (i.e. estrogen, testosterone deficiency) drug therapy (glucocorticoids) genetic disorders nutritional

Answer 18

increases Ca reabsorption, decreases P reabsorption to avoid precipitation Another Imp thing PTH does is to Facilitate PO4 secretion-IMPORTANT as the CaPO4 is insoluble; If the levels of CaPO4 go above the level its soluble , its solubility product constant, it will precipitate (not good). To prevent this, PTH increases Po4 excreation, and promotes Ca reabsorption in the Kidney, thus overall, PTHà increases Ca in the blood/serum Thus it increases PO4 secretion/Excretion at the same time as increasing Ca reabsorption

Answer 19

increases calcium absorption

Answer 20

24, 25 Source-Diet or the Sun (UV light converts Vit D to active form)- Dietary 7 – dehdr cholesterol can be converted to Vit D via hydroxylation(25 hydroxy-D) (happens in the Liver) – This is still inactive à in the kidney à Hydroxylated at 25 or 24 position. If hydroxylated at the 25- its active But if Ca/PO4 excess, it gets hydroxylated at the 24 position-leads to Inactive VIT D-Not usable/not available for activation

Answer 21

Facilitate the uptake of Ca from the GIT ..how…does that by increasing the synthesis of Calbindin (same protein that is made in the kidney) **Calbindin** then facilitates intake of Ca and its transport across the intestinal cell and secretion into the blood stream. In absence of calbindin u wont have this uptake of Ca and will result in Hypocalcemia; Thus one way to traet hypocalcemia is to give massive doses of Vit D

Answer 22

tetany seizures intellectual impairment psych **prolonged QT**

Answer 23

less Ca will be bound to albumin (because it will be displaced by H+, so there will be increased ionized calcium how you correct ionized Ca is to correct for albumin **more H+ --\> more ionized Ca**

Answer 24

NTX - urine CTX - serum

Answer 25

short QT high Ca

Answer 26

increase calcium reabsorption

Answer 27

increased PTH due to a defect in the negative feedback mechanism usually adenomas or hyperplasia

Answer 28

same phenotypic appearance as pseudohypothyrodism but normal PTH and PTH response ## Footnote Both have the phenotype of pseudohypoparathyroidism, i.e. the genetic defect-Obesity, round face short metacarpals HOwever, Only daugther has the chemical abnormality, ie she is hypocalcemic- Not the mother Mother-Pseudopseudo; daughter is Pseudo.. Pseudo means PTH is not low, its actually high

Answer 29

- bound to anions - bound to albumin - ionized Ca albumin is low - total Ca might be low but ionized will be normal ·Measuring total Ca2+ can be misleading – we need to interpret values based on other clinical entities pts have oIf albumin is low, total Ca can be low but ionized Ca2+ can be normal oEx: Calcium is 7.8 but albumin is 2, so we must correct for it. Patient is not necessarily hypocalcemic oEx2: Multiple myloma ↑ albumin, so total Ca is high, but ionized Ca may be normal

Answer 30

C cells-secrete PTH; And they Have receptors called Ca sensing receptors-which are Able to monitor the levels of circulating Ca in blood

Answer 31

fatigue, deprssion, confusion, coma anorexia, nausea, vomiting, constipation polyuria, dehydration (trying to get rid of Ca in urine)

Answer 32

post-menopausal women or men \> 50 with: hip/vertebral fracture T score \< 2.5 low bone mass (osteopenia) + FRAX

Answer 33

malignancy/other rare conditions hypercalcemia in 5-30% of malignancy! poor prognostic factor

Answer 34

low bone mass -1.0 to -2.5 = t score

Answer 35

Osteoprotegerin is a decoy receptor for the receptor activator of nuclear factor kappa B ligand (RANKL). By binding RANKL, OPG prevents RANK OPG can reduce the production of osteoclasts by inhibiting the differentiation of osteoclast precursors (osteoclasts are related to monocytes/macrophages and are derived from granulocyte/macrophage-forming colony units (CFU-GM)) into osteoclasts and also regulates the resorption of osteoclasts in vitro and in vivo. OPG binding to RANKL on osteoblast/stromal cells, blocks the RANKL-RANK interaction between osteoblast/stromal cells and osteoclast precursors. This has the effect of inhibiting the differentiation of the osteoclast precursor into a mature osteoclast.

Answer 36

80% benign single adenoma, 15% chief cell hyperplasia (carcinoma rare!) High Ca, Low P PTH stimulates osteoclasts --\> bone breakdown

Answer 37

selective estrogen receptor modulator like estrogen! antiresoprptive like estrogen without the negative side effects (i.e. uterine) It’s used in women who are not close to menopause because the downside is it can bring back hot flashes if somebody is too close to menopause and still having them or just within that, so a few years after menopause. It’s not as potent as other drugs but it’s a good drug to increase bone and decrease fracture at least to some extent

Answer 38

T score greater than 2.5 standard deviations below the mean peak adult bone mass (at a young age)

Answer 39

oral can cause GI upset + adherance issues IV = once per year!! but people don't like to be stuck

Answer 40

sign of hypocalcemia BP cuff for 3 min - occlude brachial artery if no blood flow --\> hypocalcemia/NM irriitibility --\> spasm of muscles of hands and forearm

Answer 41

decreases fracture risk in hip and spine! not primary bone drug but good if going on it anyway It also decreases RANK-L and stimulates the OPG. So all of these things are going to affect that osteoclast and slow down breakdown. And we know that it decreases fracture risk in the hip and the spine. So if estrogen is indicated for other reasons, we know it’s a good bone drug and we know how it works. But the question normally is are we giving them estrogen for another reason. We use it less as a primary bone drug because of all of the other estrogen pros and cons.

Answer 42

less H+ --\> more calcium bound to albumin --\> decreased ionized calcium

Answer 43

Increase the no of channels in the Luminal/Apical membrane in the Distal tubule. These are increases in no/more are inserted in the Apical membrane, more syntheiszed in the presence of PTH; allowing more Ca to enter the cells.

Answer 44

thyroid releases _calcitonin_ **increase deposition in bones** **decrease ca uptake in intestines** **decrease ca reabsoprption from urine** decrease calcium

Answer 45

femoral neck total hip spine

Answer 46

inhibits osteoclast motility, differentiation, secretion long term: decreases number, inhibits bone resportion inhibits renal calcium reabsorption

Answer 47

PTH secretion depends on levels of Ca and the Ca sensing receptors that detect these levels Some people are born with defects in these receptors, then one needs higher levels of harmone to stimulate the same receptors, this results in FHH(Familial hyprecalcemic hypercalceuria). These Pt’s have hypercalcemia as the Ca levels have to be pretty high before the PTh is turned off. desensitized! set point moved to the right

Answer 48

hypocalcemia and hyperphosphatemia BUT HIGH PTH children usually indicitive of resistance to all actions of PTH

Answer 49

caclium supplements vit d weight-bearing exercise

Answer 50

1. increase TRPV5 channel on lumenal membrane so Ca can enter 2. increase calbindin - binds calcium 3. stimulate Ca transporter on basolateral membrane **vit D = steroid-like, transcription and translation of many things**

Answer 51

all is diffusible calcium **most is ionized (active form) - only kind that is accessible to cells** some is insoluble - bound to phosphate!!

Answer 52

bone density + bone quality can only measure density

Answer 53

alendronate (most common) risedronate (most common) ibandronate - data not as good

Answer 54

anti-resorptive ab to RANKL blocks activation of osteoclasts decreases fracture risk in hip and spine

Answer 55

BSAP (Bone specific alk phos) OC (osteocalcin)

Answer 56

rare LOF of CASR gene --\> **decreased sensitivity to Ca** hypercalcemia and rel hypocalciuria no typical complications of high serum Ca

Answer 57

increase Ca resprption ## Footnote effect-of PTh is to Increase resorption of bone; As bone is being resorbed, it Increases not only Ca++ but also PO4 levels in the blood- both go up in the serum as bone is being resorbed/broken down.

Answer 58

anti-resoprptives target osteoclasts - decreases recruitment, differentiation, action leads to **apoptosis of osteoclastis** **increase OPG** (inhibits RANK + RANKL)

Answer 59

short - hypercalcemia long - hypocalcemia

Answer 60

Parathyroid hormone-related protein (or PTHrP) is a protein member of the parathyroid hormone family. It is occasionally secreted bycancer cells (breast cancer, certain types of lung cancer including squamous cell lung carcinoma)

Calcium Flashcards

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