Urine specific gravity
A quick measure of how concentrated the urine is — essentially how much dissolved material it carries compared with pure water. It reflects hydration and the kidneys' ability to concentrate urine, and is part of a routine urinalysis rather than a stand-alone test.
What it measures
Urine specific gravity is a simple measure of urine concentration: how much dissolved material (salts, urea and other solutes) the urine carries relative to pure water, which has a value of 1.000. It is reported on the dipstick as part of a routine urinalysis. Its main uses are to gauge hydration and to test how well the kidneys can concentrate or dilute urine. When you are dehydrated, healthy kidneys conserve water, producing concentrated urine with a high specific gravity; when you drink a lot, they make dilute urine with a low value. So specific gravity moves with your fluid state. It also gives a clue to kidney function: kidneys that have lost the ability to concentrate urine — as in some chronic kidney diseases or in conditions like diabetes insipidus — produce urine that stays dilute and 'fixed' even when the body needs to conserve water. A very high value can be seen with dehydration, high glucose or after some contrast dyes. Because it is affected by anything dissolved in the urine, specific gravity is a rough, quick guide read alongside the rest of the urinalysis and, where more precision is needed, urine osmolality.
What a high value can mean
- Dehydration — the commonest reason; concentrated urine as the kidneys conserve water.
- Reduced fluid intake or fluid loss — fever, sweating, vomiting or diarrhoea.
- Glucose or protein in the urine — extra dissolved material raises the value.
- After certain X-ray contrast dyes — can give a very high reading.
What a low value can mean
- Over-hydration — dilute urine after drinking a lot of fluid.
- Reduced ability to concentrate urine — in some chronic kidney disease.
- Diabetes insipidus — the kidneys cannot concentrate urine, producing large volumes of dilute urine.
- A 'fixed' value near that of blood — can suggest the kidneys have lost their concentrating ability.
When to discuss with a doctor
Urine specific gravity is a quick, supportive measure rather than a decisive test on its own. Most often it simply reflects how hydrated you are at the moment of the sample, so a high or low value in isolation is usually not a concern. Its more meaningful use is as one clue to how well the kidneys can concentrate urine: urine that stays persistently dilute despite dehydration, or a 'fixed' value, can point toward reduced kidney function or a water-balance disorder, and is followed up with more specific tests such as urine and serum osmolality. It is always read within the whole urinalysis and clinical picture. Mediora.AI shows specific gravity alongside the rest of the urinalysis and kidney markers so the concentration and hydration pattern is visible; interpreting it belongs with your doctor.