Urine
Urine screening
Laboratory screening of ten urine parameters, including protein, glucose, blood cells, nitrite, pH and specific gravity. You collect the sample at home.
€ 35,00
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Urine tests · Urine
Specific gravity
How concentrated the urine is; mainly says something about how much you have drunk.
At a glance
- Measured in urine
- In 1 test panel
- Check the preparation
Explanation
Specific gravity: what is measured?
The specific gravity shows how many dissolved substances are in the urine, compared with water. Healthy kidneys make concentrated urine when you drink little and diluted urine when you drink a lot. The pad on the dipstick measures the amount of salts (ionic strength), not glucose or protein; as a result, the result can differ from a measurement with another device in the laboratory. The value also helps to interpret the other dipstick results: substances are more easily missed in diluted urine.
What can it detect?
- How much fluid you have drunk or lost, for example with dehydration
- Whether the kidneys can concentrate urine
Result
What does the result mean?
Specific gravity too high
A high specific gravity means concentrated urine. This is normal in first morning urine and is otherwise usually caused by drinking little, sweating a lot, fever, diarrhea or vomiting. In concentrated urine, other parts, such as protein, are more quickly slightly positive.
Specific gravity too low
A low specific gravity means diluted urine. This is usually caused by drinking a lot, alcohol, coffee or water pills (diuretics). If the urine stays diluted even after a night without drinking, together with a lot of thirst and frequent urination, this can fit a kidney problem or, rarely, a hormonal disorder in which the body does not retain water properly (diabetes insipidus). In diluted urine, other parts can be false negative.
After an abnormal result
An abnormal specific gravity on its own usually does not lead to further tests; it mainly helps to interpret the other results. With a persistently low specific gravity together with a lot of thirst and frequent urination, the GP looks at blood sugar, kidney function and salts in the blood.
Reliability
How reliable is the test?
A urine dipstick is a quick screening and not a diagnosis. According to the Dutch GP guideline (NHG) on urinary tract infections, the dipstick is a first step with symptoms that fit a bladder infection; if in doubt, a culture or sediment test follows. For detecting kidney damage, the dipstick is less sensitive than the albumin-creatinine ratio in urine and the eGFR in blood; the NHG guideline on chronic kidney damage is based on those. In people without symptoms, most abnormal dipstick results are temporary or harmless; a single abnormal result therefore says little.
What can affect the result?
- Sample collection: preferably use first morning urine or urine that has been in the bladder for at least 4 hours, and after washing, catch the middle part of the stream (midstream), so that no discharge or skin bacteria get into it.
- Menstruation, and the days before and after it, often gives a positive result for blood and sometimes for leukocytes and protein; it is better to collect at another time.
- Vitamin C (supplements or a lot of fruit juice) can suppress the reaction for blood, glucose, nitrite and bilirubin and give a false negative result.
- Heavy exercise, fever and dehydration in the day before sample collection can temporarily cause protein, blood or ketones. Urine that has been standing for a long time or has become warm gives less reliable results, especially for nitrite, bilirubin, urobilinogen and pH.
Preparation
- Preferably use the first morning urine, or urine that has been in your bladder for at least 4 hours.
- Collect the middle part of the stream.
- Do not collect urine during your period.
Who it is for
Who is the test useful for?
Useful for
Useful with symptoms that may fit a bladder infection, such as frequent and painful urination, or as a simple addition to blood tests for the kidneys, sugar or liver. For detecting kidney damage in diabetes or high blood pressure, the albumin-creatinine ratio in urine says more than the dipstick. In people without symptoms and without risk factors, the chance of a harmless abnormality is greater than the chance of a real condition.
How common is it?
Bladder infection is one of the most common infections in women; in men it is much less common. Chronic kidney damage occurs in about 1 in 10 adults, usually without symptoms. In people without symptoms, an abnormality on the dipstick is found in some, usually without a serious cause.
NHG guideline on urinary tract infections; NHG guideline on chronic kidney damage
Get tested
Specific gravity: test panels
Specific gravity is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
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