Osmolality (Urine)
Private urine Osmolality testing in London for £88, measuring one kidney and fluid-balance marker with results expected in around 3 days.
Turnaround time
3 business days
Biomarkers count
1
Book your test
Choose Service Type
Professional phlebotomist comes to you
+ £{{ home_visit_fee }}
Visit our clinic for your test
{{ clinic_visit_fee > 0 ? '+ £' + clinic_visit_fee : 'Free' }}
Home Visit Details
Home visits require at least 24 hours notice.
Select a clinic: Sorting by distance…
{{ clinicAddress(clinic) }}
{{ clinicAddress(selectedClinic) }}
Select a date
Select an hour
Available time slots: {{ timeSlots.length}}
Overview of the Osmolality (Urine) Test
particles within urine**, providing information about how effectively the kidneys concentrate or dilute urine in response to the body's water balance.
The test assesses 1 renal and fluid-balance biomarker: Osmolality (Urine).
Urine contains water together with electrolytes, urea and numerous other dissolved substances.
Osmolality reflects the total number of dissolved particles rather than the concentration of one particular chemical.
The kidneys continually adjust urine concentration.
When the body needs to conserve water, Antidiuretic Hormone, also known as ADH or Vasopressin, encourages the kidneys to retain water and produce more concentrated urine.
When excess water needs to be removed, ADH activity falls and urine becomes more dilute.
Urine Osmolality therefore provides information about renal concentrating ability and hormonal water regulation.
It can be particularly useful when investigating excessive thirst, excessive urination or abnormal Sodium concentrations.
A very dilute urine result can occur after high fluid intake.
It can also occur where ADH production or kidney response to ADH is impaired, as in diabetes insipidus.
Concentrated urine can occur with dehydration and increased ADH activity.
In syndrome of inappropriate antidiuretic hormone secretion, or SIADH, urine can remain inappropriately concentrated despite low serum Sodium or low Serum Osmolality.
For this reason, Urine Osmolality is often most informative when measured together with Serum Osmolality and Sodium.
What Does the Osmolality (Urine) Test Check?
The test measures the concentration of dissolved particles in a urine specimen. This test measures 1 biomarker.
Osmolality (Urine)
Measures total dissolved-particle concentration in urine, providing information about hydration, renal concentrating ability and Antidiuretic Hormone-related water balance.
Who May Benefit From the Osmolality (Urine) Test?
Urine Osmolality can be useful when abnormal thirst, urination, Sodium or fluid balance is being investigated.
People with excessive thirst and frequent urination - Dilute urine can help characterise disorders of water regulation.
People with unexplained high Sodium - Urine concentration can show whether the kidneys are conserving water appropriately.
People with low Sodium under clinical investigation - Urine Osmolality contributes to assessment of Hyponatraemia.
People with suspected diabetes insipidus - Urine may remain unusually dilute despite the body's need to conserve water.
People with suspected SIADH - Urine can remain inappropriately concentrated.
People with kidney disease affecting concentrating ability - Renal tubular dysfunction can alter urine concentration.
People with recurrent dehydration concerns - Urine concentration can provide additional context.
People undergoing paired Serum and Urine Osmolality testing - Comparing both measurements can clarify water-balance physiology.
How to Prepare
A formal water-deprivation test is a specialist supervised procedure and should not be attempted independently before routine urine testing.
Usual hydration should generally be maintained unless specific clinical instructions have been provided.
Symptoms and Reasons to Consider the Osmolality (Urine) Test
Abnormal water regulation can affect thirst, urination and neurological function.
Persistent excessive thirst - Disorders of water balance can produce strong thirst.
Passing unusually large amounts of urine - Polyuria can occur when the kidneys are unable to concentrate urine.
Very dilute urine despite dehydration - This can suggest impaired concentrating ability.
Unexplained low Sodium - Urine Osmolality can help distinguish different mechanisms.
Unexplained high Sodium - Water loss and inadequate urine concentration may be relevant.
Frequent night-time urination - Excessive urine production can require further investigation.
Recurrent dehydration - Kidney concentrating function may form part of the assessment.
Confusion, seizures, reduced consciousness or severe symptoms associated with abnormal Sodium can represent a medical emergency.
Urine Osmolality should not delay urgent assessment of significant electrolyte disturbance.
How to Book Your Osmolality (Urine) Test
The Urine Osmolality test can be booked privately for assessment of kidney concentrating ability and fluid regulation.
Choose the Osmolality (Urine)
Select the individual Urine Osmolality test online.
Select your sample collection option
Arrange the appropriate urine-sample collection pathway through London Blood Tests.
Provide your urine sample
Collect a fresh urine specimen in the approved container according to the instructions provided.
Laboratory analysis
Your urine undergoes measurement of Osmolality (Urine).
Receive your results securely
Your authorised result is delivered securely and can be interpreted alongside Serum Osmolality, Sodium and other kidney markers.
When Will I Receive My Results?
The current London Blood Tests page lists a turnaround of approximately 3 days after laboratory receipt.
The underlying laboratory assay can be processed more quickly, but London Blood Tests currently quotes 3 days as the customer-facing turnaround.
Transport and laboratory receipt occur before the reporting period begins.
Understanding Your Results
Urine Osmolality varies substantially according to hydration and the physiological situation.
A low result indicates relatively dilute urine.
This can be entirely appropriate after substantial fluid intake.
Persistently dilute urine when the body should be conserving water can occur with diabetes insipidus or impaired kidney concentrating ability.
A higher result indicates concentrated urine.
This can be an appropriate response to dehydration.
In other settings, an unexpectedly concentrated urine result can provide evidence of increased ADH activity.
The value should therefore not be labelled simply as normal or abnormal without considering Serum Osmolality, Sodium and fluid intake.
The relationship between blood concentration and urine concentration is usually the clinically important finding.
Why Book With London Blood Tests?
London Blood Tests provides private Urine Osmolality testing for kidney and water-balance assessment.
Measures urine concentration directly - The test quantifies total dissolved particles.
Assesses kidney concentrating ability - It shows how the kidneys respond to water balance.
Useful with abnormal Sodium - Urine concentration helps characterise both high and low Sodium states.
Relevant to diabetes insipidus investigation - Persistently dilute urine can be an important finding.
Relevant to SIADH assessment - Inappropriately concentrated urine can provide useful information.
Can be paired with Serum Osmolality - Comparing urine and blood concentrations improves interpretation.
Simple urine specimen - No blood draw is required for this individual test.
Clear pricing - The Osmolality (Urine) test costs £88.
Private Osmolality (Urine) Test in London
London Blood Tests provides private Urine Osmolality testing for people requiring assessment of kidney concentrating ability and fluid balance.
The test costs £88 and measures 1 renal biomarker.
The current London Blood Tests turnaround is approximately 3 days after laboratory receipt.
Interpretation is strongest when the result is considered alongside Serum Osmolality and Sodium.