It is an estimate of urine osmolality (the solute concentration of a. In general, the specific gravity of any substance is defined relative to water at 4C. Urine specific gravity (USG) is a comparison of the density of urine to that of water. A monochromatic light is led to the drop and the specific gravity can be measured depending on the angle of refraction of the light. According to the definition of specific gravity, it can be mathematically expressed as : S G s u b s t a n c e w a t e r. Refractometer: Only a drop of urine is needed.With a calibrated scale the specific gravity can be read depending on how much the test tube float in the distilled water. Urinometer: A test tube is filled with 10 or 20 ml of urine and then is placed in distilled water at 68-72✯ (20-22ªC).Specific gravity may be also measured at labs with other procedures. They comprise up to 10 or more different reagents or chemical pads to perform different urine tests at the same time. In laboratories, there are automated machines that perform the analysis very fast, but it is also possible to buy strips that let you analyze a urine sample at home.

Urine specific-gravity measurements normally range from 1.002. It reacts (change color) when it is dipped into the urine specimen. Urine specific gravity is a measure of the ratio of the density of urine to the density of water. The dipstick may comprise a reagent or chemical pad. The urine gravity test is measured frequently using reagent strips or dipsticks. This sample will be sent to the lab for the analysis. The patient must collect a sample of the urine in a specific container using a special kit. This test is performed along with other urine tests in what is called a urinalysis.

Specific gravity lab purpose