NPN & Bilirubin Flashcards
List the substances that are classified as nonprotein nitrogenous substances.
Urea, creatinine, creatine, uric acid, ammonia.
What is the reference range for the following NPN:
- *Creatinine**
- *(Male & Female)**
- *Male**: 0.7 - 1.3 mg/dL
- *Female**: 0.6 - 1.1 mg/dL
What is the reference range for the following NPN:
- *Uric Acid**
- *(Male & Female)**
- *Male**: 4.4 - 7.6 mg/dL
- *Female**: 2.3 - 6.6 mg/dL
What is the reference range for the following NPN:
BUN
7 - 18 mg/dL.
What is the reference range for the following NPN:
Urea
2.5 - 6.4 mmol/L.
What is the reference range for the following NPN:
Ammonia
15 - 45 ug/dL.
What is the critical value for BUN?
>100 mg/dL.
How are BUN and creatinine related clinically?
Both BUN and creatinine are indicators of renal function. Together can help identify whether renal failure is prerenal, renal or postrenal.
What is the normal ratio of BUN:CRE?
12:1 - 20:1.
Increased BUN:CRE ratio may indicate what?
Disease due to nonrenal conditions, ration >20:1.
Decreased BUN:CRE ratio may indicate what?
Interference in creatinine analysis or marked increase in creatinine clearance.
Explain the clinical significance of the following NPN:
Urea
Associated with impaired renal function.
Explain the clinical significance of the following NPN:
Creatinine
Useful index for renal function, primarily glomerular filtration.
Explain the clinical significance of the following NPN:
Creatine
Increased in skeletal muscle necrosis or atrophy.
Explain the clinical significance of the following NPN:
Uric Acid
Increased in advanced chronic renal failure, gout, and toxemia of pregnancy.
Explain the clinical significance of the following NPN:
Ammonia
Increased in Reye syndrome and establishes diagnosis of impending or existing hepatic coma.
Define azotemia.
Excess NPN retained in the blood.
Explain uremia or uremic syndrome.
Increased urea in the blood, which represents an advanced stage of renal disability and worse stage of azotemia.
This is eventually fatal if not treated by dialysis.
The level of urea in the plasma is markedly affected by what factors?
- Renal function
- Protein content of diet
- Fever
- Major illness
- Stress
- Level of protein catabolism occurring
When would there be a notable decreased in urea concentration?
- Low protein intake
- Increased protein synthesis (pregnancy)
Describe the Berthelot reaction for BUN testing.
A spectrophotometric approach of indirect measurement of urea which was hydrolyzed from urea with urease.
A disadvantage of the Berthelot reaction is…
Sensitive to ammonia contamination.
What is the reference interval for creatinine clearance.
- *Male**: 97 - 137 mL/min/1.73 m2
- *Female**: 88 - 128 mL/min/1.73 m2
Describe the purpose of creatinine clearance.
Assess the glomerular function of the kidney.
It is an estimate of the amount of plasma that is filtered through the glomerulus per minute with complete removal of creatinine C.
Practically the same as glomerular filtration ratio.
How much muscle creatinine is converted to creatinine daily?
1 - 2%.
What type of specimen is needed for creatinine clearance testing?
4, 12, or 24-hour urine specimen and a blood specimen.
Describe the procedure for creatinine clearance.
The volume of urine is measured, urine flow rate is calculated, and the assay for creatinine is performed on plasma and urine to obtain the concentration in mg/dL or mg/mL.
Describe the formula for creatinine clearance.
Where…
UCr is urine creatinine concentration
PCr is plasma creatinine concentration
VU is the volume of urine
t is time
