NPN Compounds

Question 1

Explain the chemical structure, synthesis and mode of excretion or urea

Question 2

State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/ source of error, and the usefulness of the BUN assay

Answer 2

-Major excretory product of protein metabolism/catabolism
-These processes release nitrogen, which is converted to ammonia
-Synthesized in the liver from CO2 and Ammonia that arises from deamination of amino acids
-Ref range serum: 6-20 mg/dL
-24-hour urine ref range: 12-20 g/dL

-Assays for urea were based on measurement of nitrogen, the term blood urea nitrogen (BUN) has been used to refer to urea determination.
-Excreted by the kidneys - 40% reabsorbed
-<10% of the total are excreted through the gastrointestinal tract and skin.
-Concentration is determined by: renal function, dietary intake, protein catabolism

Question 3

Measurement of urea is used to:

Answer 3

-evaluate renal function
-Assess hydration status (the amount of urea reabsorbed depends on urine flow rate and extent of hydration.
-Determine nitrogen balance
-Aid in the diagnosis of renal disease
-And to verify adequacy of dialysis

Question 4

Azotemia

Answer 4

elevated concentration of urea in blood

Question 5

uremia or uremic syndrom

Answer 5

very high plasma urea concentration accompanied by renal failure

Question 6

Discuss ideas states and disorders associated with urea measurements in pre-renal causes

Answer 6

-reduced renal blood flow –> Less blood is delivered to the kidney –> less urea filtered

-Anything that produces a decrease in functional blood volume, include: Congestive heart failure, shock, hemorrhage, dehydration, burns

-High protein diet or increased catabolism (fever, major illness, stress)

Question 7

Discuss ideas states and disorders associated with urea measurements in renal causes

Answer 7

-decreased renal function causes increased blood urea due to poor excretion. Examples: acute & chronic renal failure, glomerular nephritis, tubular necrosis (caused by a lack of oxygen to the kidneys - ischemia )

Question 8

Discuss ideas states and disorders associated with urea measurements in post-renal causes

Answer 8

-Obstruction of urine flow (renal calculi), tumor of bladder or prostate, severe infection

Question 9

decreased urea nitrogen

Answer 9

-low protein dietary intake
-liver disease (lack of syntheis)
-Severe vomiting and/or diarrhea (loss)
-Increase protein synthesis

Question 10

Creatinine is synthesized in

Answer 10

liver

Question 11

creatinine is converted to creatine phosphate for

Answer 11

high energy source for muscle tissue

Question 13

Discuss ideas states and disorders associated with urea measurements in decreased formation (liver disease)

Question 14

Discuss ideas states and disorders associated with urea measurements in over-hydration: dilution

Question 15

Discuss ideas states and disorders associated with urea measurements in end stage renal disease

Question 16

Explain the chemical structure, synthesis and mode of excretion of creatinine

Question 17

State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/ source of error, and the usefulness of the creatinine assay

Question 18

State the reference range and explain the usefulness of the BUN/Creat ration

Question 19

Discuss disease states and disorders associated with creatinine measurements especially in Muscle wasting disease

Question 20

Discuss disease states and disorders associated with creatinine measurements especially in Renal disease

Question 21

Use protocol for performing creatinine clearance test

Question 22

Calculate creatinine clearance results using body surface area normalization

Question 23

Recognize factors that can influence eGFR results (age, muscle mass, gender, race)

Question 24

Explain the chemical structure, synthesis and mode of excretion of uric acid

Question 25

Discuss methodologies for uric acid

Question 26

Discuss disease states and disorders associated with uric acid measurement in renal disease

Question 27

Discuss disease states and disorders associated with uric acid measurement in gout

Question 28

Discuss disease states and disorders associated with uric acid measurement in increased cell turnover

Question 29

Explain the chemical structure, synthesis and mode of excretion of ammonia

Question 30

Discuss methodologies for ammonia

Question 31

Discuss disease states and disorders associated with uric acid measurement in Reyes syndrome

Question 32

Discuss disease states and disorders associated with uric acid measurement in Fanconi’s syndrome

Question 33

Discuss disease states and disorders associated with uric acid measurement in liver disease