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Flashcards in CKD-bone and mineral dz Deck (18):
1

what are the effects of PTH?

increase bone resorption, increase conversion of 25OH-D to 2,25OH-D and thus increase intestinal Ca absorption

2

how does hypoalbuminemia affect ionize Ca conc?

it increases it b/c normally Ca is bound to albumin

3

what are the three major hormones regulating Pi?

vit. D, PTH, FGF23

4

Two methods of intestinal Pi uptake

passive (via Npt2b transporters) and active (stimulated by calcitriol)

5

Calcitriol

active metabolite of Vit. D. Stimulates active Ca (major factor) and Pi (minor factor) absorption.

6

factors that increase Pi excretion

Increased plasma conc, FGF23, PTH all cause endocytosis of transporter

7

FGF23: where produced. 3 actions

osteocytes in response to phosphate load. Inhibits renal 1,a-hydroxylase to decrease calcitriol, ^renal excretion, inhibit PTH

8

What channel does majority of Pi regulation and where?

Npt2b Na-P cotransporter in PT. Type 2a in apical membrane

9

Three effects of PTH

stimulates 1,a-hydroxylase to ^calcitriol; renal P excretion; ^serum Ca by bone resorption and renal reabsorption

10

principle regulator of Mg urine conc

Plasma Mg conc.. Most reabsorpt is paracellular in TAL

11

what is the problem in Familial Hypocalciuric Hypercalcemia Vs Hyperparathyroidism

hypercalcemia is not sensed (CaR mutation). PTH slightly elevated; Both CaR alleles mutated. more severe hypercalcemia and PTH elevation

12

what constitutes vit d deficiency

Serum 25(OH)D<30

13

what are the high and low turnover bone diseases

Osteitis Fibrosa (HyperPTH), Adynamic bone osteomalacia (Ca, Calcitriol, D analogs)

14

How do PTH, Ca, P change with decreasing GFR

PTH goes up but Ca and P stay constant until very low GFR then P rises

15

three principle hormonal changes in CKD

calcitriol down, FGF and PTH up

16

in what form are Ca and P deposited in soft viscera? Vascular, valves, joints, eyes?

amorphous, hydroxyapatite

17

what do we do to control P levels?

dietary, dialysis, P binders.

18

Why do we use Vit D or VDRA?

to control PTH