C12 Non-Protein Nitrogens Flashcards Preview

Clinical Chemistry > C12 Non-Protein Nitrogens > Flashcards

Flashcards in C12 Non-Protein Nitrogens Deck (30):
1

What are NPNs?

Increased in renal failure and are commonly ordered as blood tests to check renal function

2

Most important NPNs?

BUN, Creatinine, Uric Acid, and Ammonia

3

BUN

Blood Urea Nitrogen, 50% of NPNs, urea, filtered by glomerulus but also aborbed by renal tubules (40%), some is lost through the skin and GI tract (<10%)

4

Urea

by product of protein catabolism which produces ammonia

5

Ammonia

very toxic- converted to urea by the liver

6

Liver converts ammonia and CO2 into?

urea

7

Plasma BUN is affected by?

renal function, dietary protein, and protein catabolism

8

Azotemia

elevated plasma BUN

9

Prerenal (increased) BUN- not related to renal function

low bp, decreased flow to kidney, increased dietary protein or protein catabolism
increased BUN/normal creatinine

10

Prerenal (decreased) BUN- not related to renal function

decreased dietary protein, increased protein synthesis (pg women and children)

11

Renal causes of (increased) BUN

renal disease with decreased glomerular filtration (glomerular nephritis, renal failure from DM)

12

Post renal cause of (increased) BUN-not related to renal function

obstruction of urine flow- kidney stones, tumors, UTIs
increased BUN/increased creatinine

13

Renal decreased BUN

low dietary protein or severe liver disease
decreased BUN/normal creatinine

14

Creatinine

formed at a constant rate by the muscles as a function of muscle mass, removed from plasma by glomerular filtration, not secreted/absorbed by the renal tubules

15

Liver

Amino acids>creatinine

16

Muscles

Creatinine>phosphoscreatinine
phosphocreatinine>creatinine

17

Plasma creatinine?

function of glomerular filtration, unaffected by other factors, its a very good test to evaluate renal function

18

delta check

significant change from previous results

19

Jaffee Method

creatinine analytical technique
Creatinine+Picrate Acid>colored chromogen
Specimen-plasma/serum
elevated bilirubin and hemolysis causes falsely decreased results (everyone uses this technique)

20

Uric Acid

breakdown product of purines (nucleic acid/DNA), converted from liver, filtered by glomerulus (98-100% reabsorbed)

21

Elevated plasma uric acid?

can promote formation of solid uric acid crystals in joints and urine

22

Uric acid diseases?

Gout (increased plasma uric acid, acid crystals in joints, associated with alcohol consumption, may also form kidney stones)
Leukemias and lymphomas
Megaloblastic anemias
renal disease

23

Uric acid absorbs light at?

293 nm, rate of decreased absorption is proportional to the uric acid concentration

24

Ammonia

produced from the deamaination of amino acids, bacterial enzymatic conversion of GI tract protein, muscle catabolism

25

Causes of increased ammonia

liver disease, Reye's syndrome, sever renal disease, genetic enzyme dificiencies of the urea cycle, Valproic acid (anti-seizure medications)

26

Ammonia analytical technique

decreasing absorbance @340 nm proportional to the ammonia concentration
EDTA/Heparinized whole blood on ice, delayed testing causes false increase values

27

Creatinine clearance

calculated measurement of the rate at which creatinine is removed from the plasma by the kidneys, measurement of glomerular filtration

28

Creatinine is?

an endogenous substance (not affected by diet), filtered by glomerulus but not secreted or reaborbed by renal tubules

29

Creatinine clearance specimens?

24 hr urine specimen
plasma/serum creatinine collected during the urine collection

30

Creatinine Clearance Formula

(UV//P)(1.73/A)
U=creatinine concentration of the 24 hr urine (mg/dl)
V=24 hr urine volumes, V=V/1440=ml/min
P=plasma creatinine concentration (mg/dl)
A=correction factor accounts for differences in BMI