quantitative analysis of urine

1. Biochemistry Practical 2
(Quantitative Analysis of Urine)
Copied & Edited from Handout of Dr. Atif By :
Osama Al-Zahrani
@OSAMA_Z96

2. Estimation of Blood Urea
• The concentration of urea in the plasma is determined by :
1- Renal function.
2- The protein content in diet.
3- The rate of protein catabolism.
• Normal (reference) range of blood urea :
2.6 – 6.6 mmol/L
15 – 40 mg/dl
For conversion of mmol/L to mg/dl : (mmol/L) X 6 = mg/dl
Example.. (9 mmol/L) X 6 = 54 mg/dl

3. Clinical Use of Estimation of Blood Urea
•Measurement of urea (BUN) is used in :
1- Evaluate renal function.
2- To assess hydration status.
3- To determine nitrogen balance.
4- To diagnose renal diseases.
5- To verify adequacy of dialysis.

4. Estimation of Blood Urea
• Increased blood urea or BUN (azotemia) may be due to:
1- High protein diet.
2- GIT bleeding.
3- Increased protein catabolism (trauma, surgery,, extreme starvation.
4- Impaired renal function.
5- Dehydration, volume depletion.
6- Cardiac failure.
7- Urinary tract obstruction .
• Low levels of urea in the blood suggest:
1- Malnutrition.
2- Low protein diet.
3- Liver disease.
4- Pregnancy.
5-Water retention.

5. Estimation of Urine Urea
• High levels of urea in the urine may suggest:
1- High protein diet.
2- Increased protein breakdown in the body.
• Low levels of urea in the urine may suggest:
3- Malnutrition.
4- Low protein diet.
5- Kidney problems.

6. Formula :
Sample 1 : Urine Urea (Uu) conc. (mg/dl) = × conc. Standard
Example :
If the Absorption test (Ab.T) = 0.480 ml
If the Absorption standard (Ab.St) = 0.040 ml
If the conc. Standard = 80 mg/dl
Then : Uric acid conc. = × 80 = 960 mg/dl (Normal). Normal range of Urine Urea : 400 – 1200 mg/dl
Sample 2 : Plasma Urea (Pu) conc. (mg/dl) = × conc. Standard
Example :
If the Absorption test (Ab.T) = 0.242 ml
If the Absorption standard (Ab.St) = 0.040 ml
If the conc. Standard = 80 mg/dl
Then : Uric acid conc. = × 80 = 484 mg/dl (Abnormal). Normal range of Plasma Urea : 15 to 40 mg/dL
Estimation of Urea
Ab.S
Ab.T
0.040
0.480
Ab.S
Ab.T
0.040
0.242

7. Urea clearance is calculate by the following formula :
Cu =
Cu : Urea clearance in ml/minute
Uu : Urine urea in mg/ml
V : Volume of urine in ml/day
Pu : Plasma urea in mg/ml
• From previous formula in the previous slide :
Uu : 960 mg/ml
V : 1500 ml/day
Pu : 484 mg/ml
Cu = = 2.9 ml/minute (Abnormal)
Normal Range of Urea clearence :
64 – 99 ml/minute
Urea clearance
Pu
Uu X V
960 X 1500
484

8. BUN / Creatinine
• = (BUN in mg/dL)/(serum creatinine in mg/dL.)
• For a normal individual on a normal diet, the reference interval for the ratio ranges between 12 and 20, with most
individuals being between 12 and 16.
• The ratio is indicative of pre-renal injury when the BUN/Cr. ratio is greater than 20
• Lower ratios :
1- Low protein intake, starvation
2- Severe liver disease.
• High ratios with normal creatinine levels indicate :
1- High protein intake
2- Catabolic states of tissue breakdown pre-renal azotemia.
• High ratios associated with high creatinine indicate :
- Post-renal obstruction.
BUN
Creatinine