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: Urine Specific Gravity by Refractometry

Published: August 9, 2026Updated: August 16, 2026

: This test measures the concentration of your urine using a refractometer, which estimates how much dissolved material is present compared with water. It helps show how well your kidneys are balancing water.

Quick summary

[": Urine specific gravity is a simple indicator of urine concentration and hydration status."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
50562-8
Short code
Sp Gr Ur Refract.auto
Synonyms
Sp Gr Ur Refract.auto
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
refractometry-automated
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

: What This Test Measures

: Specific gravity compares the density of your urine to the density of water. A refractometer uses light bending through a urine sample to estimate this value, giving a picture of how concentrated or dilute the urine is.

: How the Sample Is Collected

: A routine urine sample is collected, usually as a clean-catch midstream specimen. No special preparation is typically needed unless your care team gives other instructions.

: What Results Can Mean

: Higher values generally suggest more concentrated urine, which can occur with limited fluid intake or other conditions, while lower values suggest dilute urine. Many factors affect results, so your provider interprets them alongside your symptoms and other tests.

: Why Refractometry Is Used

: Refractometry is a quick, common laboratory method for estimating urine specific gravity. It is often used as part of a urinalysis to help assess hydration and kidney concentrating ability.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

: Urine specific gravity supports evaluation of hydration, kidney function, and conditions that affect urine concentration. It is not a diagnosis by itself and should be interpreted with the full urinalysis and clinical context.

Short name

: Urine Specific Gravity

Frequently asked questions

: Does this test require fasting?
: Usually no fasting is required for a routine urine specific gravity test, but follow any instructions from your care team.
: Can drinking a lot of water affect the result?
: Yes, fluid intake can change urine concentration and therefore the specific gravity result, so timing and hydration can matter.
: Is this the same as a urine dipstick test?
: No, refractometry uses a different method to estimate specific gravity; a dipstick is a separate chemical screening test, and they may be used together.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy