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Urine specific gravity
Shows how well the kidneys concentrate and dilute urine. The main marker of the kidneys’ concentrating ability.
Other names: SG, Specific GravitySection: UrinalysisSpecialist: Primary care physician, nephrologist, endocrinologistSample: UrinePart of: Urinalysis
Updated: September 17, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortNormal specific gravity of morning urine is 1010–1025 g/L; during the day it fluctuates between 1003 and 1035. A low value signals weak concentrating ability of the kidneys or heavy drinking, a high one — dehydration, glucose or protein in urine.
What this marker is
Specific gravity shows the concentration of substances dissolved in urine — salts, urea, creatinine. The more of them, the higher the density. Healthy kidneys can both concentrate urine when fluid is scarce and dilute it when there is excess.
So density is judged in the morning sample (after the overnight “dry” period it should be high) and, if needed, by the Zimnitsky test with 8 portions over 24 hours. Persistently low morning density is a signal to check the kidneys.
about 1010 g/L in all portions — a sign of chronic kidney disease
A single random sample says little: after heavy drinking density is low in everyone. What matters is the morning sample and the Zimnitsky test dynamics. Ranges differ between laboratories.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
An approximate comparison with a typical range, not a diagnosis. Ranges differ between laboratories — use the one on your report; a doctor interprets the result.
When it is high or appears: possible causes
DehydrationToo little drinking, vomiting, diarrhea, heat — kidneys save water.
Glucose in urineIn diabetes sugar pulls water and raises density.
Protein in urineMarked proteinuria increases specific gravity.
Contrast agentsA recent contrast study temporarily raises density.
When it is low: possible causes
Heavy drinkingThe safe and most common cause of low density.
Chronic kidney diseaseKidneys lose the ability to concentrate urine.
Diabetes insipidusLack of antidiuretic hormone — large volumes of dilute urine.
DiureticsWater pills dilute urine.
What can skew the result
These factors can shift the result without any disease — keep them in mind before a retest:
Heavy or scarce drinking the day beforeHeat and sweatingDiureticsContrast agent within 1–3 days before the test
How to prepare
A midstream sample of the first morning urine after cleaning the genital area, in a clean container, delivered to the lab within 1–2 hours. Details: Preparation: urine.
When a retest makes sense
A doubtful result is retested in 1–2 weeks with careful preparation. During treatment of a urinary tract infection, a follow-up is done 1–2 weeks after the course, as prescribed by the doctor.
Who usually reviews this result
An out-of-range result is usually reviewed by: Primary care physician, nephrologist, endocrinologist. Bring your report and any previous results to the visit.
Names used on lab reports
Look for one of these names on your report: Urine specific gravitySGSpecific GravityRelative density of urine
Several markers on your report?
The app reads your whole report — this marker together with its neighbors, not one by one.
If you drank a lot, it is normal. What matters is persistently low density in the morning sample with a usual drinking regime: the doctor will order a Zimnitsky test and check the kidneys.
What is the Zimnitsky test?
Urine is collected in 8 portions over 24 hours, every 3 hours. By the swings of volume and density the doctor sees how the kidneys concentrate urine day and night — the main test of concentrating function.
Why is density high in diabetes?
Glucose in urine “pulls” water and adds dissolved matter — density rises. So a high value is always checked together with urine and blood glucose.
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