Non protein nitrogen

Question 1

What are nonprotein compounds

Answer 1

Uric acid, creatinine, urea, ammonia

Question 2

What enzyme catalyzes the conversion between creatinine and creatine

Answer 2

Creatinine kinase (CK)

Question 3

What happens when creatine is converted to creatinine

Answer 3

creatine loses water or creatine phosphate loses the phosphate

Question 4

Creatine is produced in…

Answer 4

Kidneys (converted to creatinine), liver, pancreas

Question 5

What can cause elevations in creatinine?

Answer 5

Associated with abnormal kidney function particularly glomerular function. As filtration fails, more creatinine in the plasma

Question 6

Jaffe reaction

Answer 6

Creatinine reacts with picric acid in alkaline conditions to form an orange-yellow chromogen. measured at 510 nm

Question 7

Issue with Jaffe test

Answer 7

lack of specificity for creatinine with many known interferences.

Question 8

Gold standard method for creatinine measurement

Answer 8

Isotope dilution mass spec

Question 9

What fluids are used to measure creatinine

Answer 9

plasma, serum and urine

Question 10

How long is creatinine stable in separated serum

Answer 10

minimum of 7 days at 4C or -20C
Separated from RBCs to prevent false elevated results

Question 11

Creatinine reference ranges serum

Answer 11

M: 0.9-1.3mg/dL
F:0.6-1.1mg/dL

Question 12

What is urea

Answer 12

Major byproduct of protein metabolism cleared at kidneys (90%)

Question 13

Does renal impairment associate with high or low serum levels?

Answer 13

Elevated serum levels

Question 14

Prerenal stats

Answer 14

Elevated plasma urea, normal creatinine, high ratio

Question 15

Postrenal stats

Answer 15

high ratio, high creatinine

Question 16

Normal BUN/creatinine ratio

Answer 16

10:1 / 20:1

Question 17

Enzymatic method for urea

Answer 17

Urease method.

Question 18

What does the urease method measure? what nm?

Answer 18

It measures the decreasing concentration of ammonia at 340nm

Question 19

urea reference range for <60y/o

Answer 19

6-20 mg/dl

Question 20

urea reference range >60y/o

Answer 20

8-23 mg/dl

Question 21

What is uric acid

Answer 21

major breakdown product of purine nucleosides adenosine and guanosine

Question 22

When is uric acid increased?

Answer 22

Gout, hyperuricemia, Lesch-Nyhan syndrome, kidney disease, diabetic ketoacidosis

Question 23

What is hyperuricemia

Answer 23

overproduction of purines, decreased tubular excretion, increased dietary intake

Question 24

Lesch-nyhan syndrome

Answer 24

x-linked genetic disorder, males only. Intellectual disability, abnormal muscle movement and behavior issues. Lack of HGPRT enzyme

Question 25

Gout treatment

Answer 25

NSAIDs, dietary avoidance of red meat, liver and kidney. Medication avoudance and pharma intervention.

Question 26

Hypouricemia

Answer 26

Serum uric acid <2.0 mg/dl. Secondary to underlying conditions like hepatocellular disease or fanconi syndrome

Question 27

Uric acid reference intervals man and woman

Answer 27

M: 3.5-7.2 mg/dl
F: 2.6-6.0 mg/dl

Question 28

Measuring uric acid

Answer 28

Uricase method, converts uric acid to allantoin. Not many interferences.

Question 29

Ammonia

Answer 29

byproduct of protein metabolism, produced by bacteria and is toxic.

Question 30

Ammonia clinical application

Answer 30

Hepatic failure, Reye’s syndrome, urea cycle abnormalities

Question 31

Measuring ammonia

Answer 31

glutamate dehydrogenase

Question 32

ammonia reference range

Answer 32

19-60 ug/dl