Urine Specific Gravity

Sample for Urine Specific Gravity

• A random urine sample can be taken.

Indications for Urine Specific Gravity

1. Urine analysis is part of the routine diagnostic profile.
2. This gives an idea about kidney function.
3. This also gives an idea about the hydration status.

Precautions for Urine Specific Gravity

1. Urine collected after the I/V administration of iodine-containing radiopaque material gives high values of specific gravity.
2. Glucose and the protein in the urine also have a high value.
3. Diabetic patient with hyperglycemia gives high value.
4. Patients after contrast radiography and dextran infusion may have high specific gravity.
5. The temperature also has an effect on the specific gravity, as it is increased in the cold.
6. In the case of detergent in the container may give high specific gravity.
7. Diuretics and antibiotics give rise to high specific gravity.

Definition of specific gravity:

1. Urine-specific gravity is the measure of the kidney’s ability to concentrate urine.
2. The important process of reabsorption by the kidneys is often the first renal function to become impaired.

Urine Specific gravity facts:

1. So the specific gravity will detect dehydration or abnormality in the antidiuretic hormone.
2. Urine is a solution of minerals, salts, and other compounds dissolved in water.
3. Specific gravity = water + dissolved chemicals.
4. So specific gravity is the measure of the density of dissolved substances in the urine.
5. Specific gravity is the weight of urine compared to distilled water, which has a specific gravity of 1.000.
6. The specific gravity of the plasma entering the glomerulus is 1.010.

Types of urine according to the specific gravity:

Isosthenuria

1. The urine-specific gravity is fixed and remains constant at around 1.010.
   1. It is not influenced by water intake or dehydration.
   2. Normal kidneys concentrate the urine in dehydration.
2. It is the urine that has not greater and not less than the protein-free plasma specific gravity.
3. It is urine with a specific gravity of 1.010 (1.008 to 1.012).
4. It suggests renal damage.
5. These patients need medical check-ups and workups.

Hyposthenuria

1. Specific gravity is low = <1.010 (1.001 to 1.010).
2. It occurs in the following conditions:
   1. Diabetes inspidus. This is due to the absence or decrease of ADH. Without  ADH, the kidneys produce an excessive amount of urine that is not reabsorbed.
   2. Glomerulonephritis and pyelonephritis. Specific gravity is low with decreased urine volume.
   3. Severe renal damage. There is a disturbance in both concentrating and diluting abilities of urine.

Hyperstheuria

1. Increased specific gravity is > 1.010 (1.025 to 1.035).
2. It is seen in the following conditions:
   1. Diabetes mellitus.
   2. Nephrosis.
   3. Increased secretion of ADH.
   4. The diuretic effect of stress of the surgical procedure.
   5. Excessive loss of water due to dehydration, fever, diarrhea, and vomiting.
   6. Toxemia of pregnancy.
   7. Cardiac diseases like congestive heart failure.

Random sample = 1.003 to 1.035.

1. Most random sample = 1.015 to 1.025.
2. A specific gravity of 1.023 or higher is generally considered normal.
3. Specific gravity >1.035 is usually seen in the renal pyelogram (IVP).
4. Specific gravity <1.003 is not urine.

Specific gravity depends upon the following:

1. The state of hydration.
2. Urine volume.
3. High specific gravity indicates concentrated urine.
4. Low specific gravity indicates dilute urine.
5. The reflectometer can read specific gravity.

Normal urine specific gravity

Source 2

Lab procedure to find the specific gravity of urine:

1. The Hydrometer checks the specific gravity but needs an abundant quantity of urine.

2. Absorbent cellulose strip impregnated with bromthymol blue, polymethyl vinyl ether, and or maleic anhydride and sodium hydroxide.
   1. The color changes to dark blue at a low specific gravity of 1.000.
   2. Yellow-green at a specific gravity of 1.030.

2. Machine-readable devices are available from the Clinitek system, Bayer Diagnostics, and Elkhart Ind.
   2. If the urinometer does not measure the specific gravity, dilute urine 1:2.
   3. Now multiply the reading by 2.

The Increased specific gravity is seen in the following:

1. Dehydration.
2. Decreased renal blood flow.
3. Diabetes mellitus.
4. Excessive water loss in fever, vomiting, and diarrhea.
5. Toxemia of pregnancy.
6. Congestive heart failure.
7. Proteinuria.
8. Water restriction.

The Decreased specific gravity is seen in the following:

1. Diabetes insipidus.
2. Early chronic failure.
3. Severe renal damage.
4. Hypertension.
5. Overhydration.
6. Diuresis.

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