Urine 24-hour

• Please provide the following written instructions to the patient for the collection of 24 hours of urine collection.

Purpose of 24-hour urine collection

1. 24-hour urine collection’s main purpose is quantitating certain substances excreted in the urine.
2. Urine samples may also be collected for 1 and 4 hours.
3. It helps in assessing kidney function.

Precautions for Urine 24 hours

1. A complete and accurate collection must be made to evaluate the required test on 24-hour urine samples properly.
2. Drink fewer fluids during the collection time unless advised by the doctor.
3. Avoid alcoholic drinks.
4. Avoid certain foods, beverages, and medication that may affect the result.
5. Do not test the chemicals needed before the required time of collection because the excretion of the substance in the urine varies.

Container for urine collection

1. Urine containers should be clean and sterile. It should have a tightly fitting lid to avoid evaporation, contamination, and spillage of urine.
   1. Label the urine bottle with name, age, sex, and date of collection.
2. For a 2-hour urine collection, the one-liter container is sufficient.
3. For 12-hour collection, the 2-liter container is sufficient.
4. For 24-hour collection, you may need a 3 to the 4-liter container.
5. A single container is preferred because of the mixing of the analytes needed for estimation.
   1. The single container also avoids the loss of urine.

Procedure for 24-hour urine collection

1. Empty the urinary bladder when you get up in the morning.
2. Note the time …………… and date ………..
   1. Discard the first urine in the urinary bladder (empty bladder), and start the clock.
   2. Thereafter, collect all the urine samples in the container.
3. Now onward, collect the urine in a clean bottle or container.
4. Collect all the urine passed during the day and night.
   1. Note the time, which will be the same………….. and date (after 24 hours) …………..
   2. Empty your bladder in the container (last-moment urine sample). Make the final collection of urine at the same time.
5. Keep the urine in the refrigerator and, if possible, bring it to the laboratory as soon as possible after the collection.
6. There may need to add chemicals like hydrochloric acid or boric acid in some of the tests as preservatives.

Urine preservatives

Purpose of urine preservative:

1. Preservatives prevent bacteria growth.
2. Preservatives prevent the decomposition of the substance to be tested.
3. Preservative prevents from precipitation of the substance to be tested.
4. Refrigeration during and after urine collection is the best preservative.
   1. Acidification of the urine (pH below 3) is used for calcium, steroids, and VMA.
   2. Sodium hydroxide (NaOH) is used for porphyrins, urobilinogen, and uric acid testing.

Mechanism of urine preservatives:

1. Urine preservatives work:
   1. Prevents decomposition of the urine.
   2. Prevents the growth of bacteria.
   3. Prevents the metabolism of the microorganism.

Urine Preservatives:

1. Hydrochloric acid (HCL) 6 mol/L, needed 30 mL for 24- hours urine sample.
2. Boric acid 10 grams per 24-hour needed.
3. Nitric acid (HNO3) 6 mol/L, 15 mL needed for 24-hour urine.
4. Sodium carbonate (Na2CO3) 5 grams needed for 24-hour urine.
5. Acetic acid 50%, 25 mL needed for 24-hour urine.

Urine preservative for various chemicals:

Chemical to be tested	Preservative	Instructions
Calcium	25 mL of 6 M HCL	Received without preservative Mix well urine Take 10 mL and add 0.1 mL 6 M HCL
Magnesium	25 mL of 6 M HCL	Received without preservative Mix well urine Take 10 mL of urine and add 0.1 mL of 6 M HCL
Phosphorus	25 mL of 6 M HCL	Received without preservative Mix well urine Take 10 mL of urine and add 0.1 mL of 6 M HCL
Uric acid	Sodium carbonate 5 grams or 10 mL of NaOH (12.5 M)	Received without preservative Mix well urine Take 10 mL of urine and add 0.1 mL 12.5 M NaOH
Creatinine	No need
Glucose	No need; keep it in the fridge
Amylase	No need; Keep it in the fridge
Protein and albumin	No need; Kepp it in the fridge
Sodium, Potassium, Chloride	No need
Creatinine	No need

Normal urine picture:

Physical features	Chemical features	Microscopic findings
Color = Pale yellow or amber Appearance = Clear to slightly hazy pH = 4.5 to 8.0 Specific gravity = 1.015 to 1.025	Blood = Negative Glucose = Negative Ketones= Negative Protein = Negative Bilirubin = Negative Urobilinogen = Negative (±) Leucocyte esterase = Negative Nitrite for bacteria = Negative	RBCs = Rare or Negative WBC = Rare or Negative Epithelial cells = Few Cast = Negative (Occasional hyaline) Crystal = Negative (Depends upon the pH of the urine) Bacteria = Negative

 

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