Urine Analysis: Part 19 – 24 hrs Urine Urea, Urine Urea Nitrogen/24 Hours

Sample

1. The test sample is urine.
2. Collected urine for 24 hours.
3. The urine sample is stable at 4 to 8 °C for 4 days or preserves with thymol to avoid bacterial action.
   1. Discard the first urine sample and note the time. Add the last sample of urine in the container.
   2. 10 grams of boric acid can be used as preservative/24 hours.

Indications

1. This test is mainly used to:
   1. Determine protein metabolism.
   2. It determines the amount of protein needed by the severely ill patient.
   3. It gives information about kidney function.
   4. It can monitor kidney disease.
   5. Patients with confirmed or suspected protein digestion and absorption problems.
   6. Patients on long-term enteral nutrition or parenteral nutrition.

Pathophysiology

1. Urea formula =     
2. Urea is the major excretory product of protein metabolism.

3. Urea is a low molecular weight substance and easily excreted by glomeruli and is mostly excreted in the urine.
4. Urea is excreted by the kidneys, so the excretion of urea can reflect kidney function.
   1. It is synthesized in the liver carried to the kidney filtered through the glomeruli mostly into the urine.

5. 40% is reabsorbed by passive diffusion.
6. The rate of absorption depends upon:
   1. Urine flow rate.
   2. The degree of hydration.
7. 10 % of urea is excreted through:
   1. GI tract.
   2. Skin.
8. Blood urea level depends upon:
   1. Renal function and perfusion.
   2. The protein content of the diet.
   3. Amount of protein catabolism.

Normal

Source 1

Urine urea nitrogen

• 12 to 20 g/day (428.4 to 714 mmol/day).

Another source

• 6 to 7 G /24 hours ( 60 to 90 mg/dL )
• Other reference says:
  • 7 to 20 g /total volume
  • 12 to 24 g /24 hours.
• This also depends upon the protein intake.

The decreased urine urea level is seen in:

1. Malnutrition.
2. Too little amount of protein in the diet.
3. Kidney dysfunction.
4. Increased reabsorption.

The increased level is seen in:

1. Excessive protein intake.
2. increased protein catabolism.

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