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Intel Lab Diagnostics Dubai
Single Biomarker

Blood Urea Nitrogen (BUN)

Kidney Waste Marker (Urea)

BUN measures the amount of nitrogen from urea in your blood. It helps assess kidney function and hydration status. Elevated levels may indicate kidney disease, dehydration, or high protein intake.

BLOOD24 HOURSNO FASTING
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  • Home collection, free from AED 300
  • Physician-reviewed report

24 hours

Turnaround

Blood

Sample

About This Test

What the Blood Urea Nitrogen (BUN) test tells you

When the body uses protein, the nitrogen left over is toxic in its raw form, so the liver converts it into urea: a small, harmless molecule that dissolves easily in blood. The kidneys then filter urea out and pass it into urine. This test measures the nitrogen carried in that urea, which is why it is called blood urea nitrogen. It is one of the oldest and most widely used indicators of how well the kidneys are clearing waste.

Its value comes with a caveat that is easy to miss: urea is not purely a kidney measurement, because production changes it too. A high-protein diet, a course of steroids, bleeding into the gut where blood is digested as protein, a severe infection, or simply being dehydrated will all raise it while the kidneys themselves may be working normally. In the opposite direction, a liver that is not making urea efficiently, a low-protein diet or a large fluid load will pull it down. Urea is also partly reabsorbed as it passes through the kidney tubules, and that reabsorption increases when the body is short of fluid.

For this reason urea is nearly always read next to creatinine, which is produced steadily by muscle and is far less influenced by diet. The relationship between the two helps distinguish a kidney that is simply underperfused (dehydration, blood loss, heart failure) from one whose filtering tissue is itself damaged. In a hot climate where fluid losses are high, a mildly raised urea with an unremarkable creatinine is frequently a hydration story rather than a kidney one, though only your doctor can make that call.

Sample type
Blood
Measured in
mg/dL
Turnaround
24 hours
Fasting
Not required
Best for
Adults & teens
Why Get Tested?

Part of routine kidney function panels. Useful for monitoring kidney disease progression, evaluating dehydration, and assessing nutritional status.

  • Assessing kidney function

    Urea is a core part of every kidney panel and gives a quick view of how well waste is being cleared. It is read together with creatinine and eGFR.

  • Detecting dehydration

    Because the kidney reabsorbs more urea when fluid is short, the value rises early in dehydration. This is a common and reversible finding.

  • Monitoring kidney disease

    Serial measurements show whether clearance is stable, improving or deteriorating. They also help guide the dosing of medicines cleared by the kidneys.

  • Investigating gut bleeding

    Blood in the digestive tract is absorbed as protein and raises urea. An unexplained rise with an unremarkable creatinine can prompt that question.

When This Test Is Ordered

Reasons your doctor may request the Blood Urea Nitrogen (BUN) test

Your doctor may order this test for any of the reasons below. Some are routine checks, others follow specific symptoms or an earlier result.

  • Routine kidney screening

    • Part of a routine kidney profile or general health screen.

  • Symptoms & dehydration

    • Symptoms such as reduced urine output, swollen ankles, persistent nausea or unexplained fatigue.
    • Suspected dehydration, particularly after heat exposure, vomiting or diarrhoea.

  • Kidney disease, medication & risk factors

    • Known or suspected kidney disease requiring assessment or follow-up.
    • Before starting or while taking medicines that are cleared by the kidneys or can affect them.
    • High blood pressure or diabetes, both of which affect the kidneys over time.
Preparation
The short version
No prep needed.
  • Blood
  • Home collection (free from AED 300)
  • No fasting
  • Results in 24 hours
  1. 1
    Book any time

    No fasting window: pick any slot that suits you, online or on WhatsApp.

  2. 2
    We come to you

    A DHA-licensed nurse collects your sample at home or in the office. Collection is free from AED 300 or with any package.

  3. 3
    Results in 24 hours

    A physician-reviewed, easy-to-read report lands securely by WhatsApp and email.

Prep note
Physician reviewed

No fasting is required for urea by itself; when it is booked inside a broader metabolic or health-check panel, follow the fasting instruction given for that panel.

Drink water normally in the day before the test (arriving dehydrated is one of the commonest reasons for a misleadingly high result), but avoid loading up on protein shakes or an unusually large meat-heavy meal for a day or two beforehand. Heavy exercise the day before is also best avoided.

Tell the team about diuretics, steroids and any recent vomiting, diarrhoea or heat exposure.

Understanding Your Results

A result in the Normal band, 7 to 20 mg/dL, suggests the kidneys are clearing urea normally. A result in the High band, above 20 mg/dL, is most often caused by dehydration, a high-protein diet, recent bleeding in the stomach or gut, some medicines such as steroids, or reduced kidney function; heart failure also raises it by lowering blood flow to the kidneys. Because so many things outside the kidney affect urea, a raised value on its own is not a diagnosis of kidney disease. A result in the Low band, below 7 mg/dL, is usually not concerning and can reflect a low-protein diet, a high fluid intake, pregnancy or, less often, significant liver disease. BUN is read with creatinine and eGFR: the ratio between BUN and creatinine helps your doctor judge whether a rise comes from dehydration or bleeding rather than from the kidneys themselves.

Medically reviewed by Dr Nirupama Sabhapathy

SmartReport
720
Healthy zone7 – 20mg/dLNormal
Reference ranges · mg/dL
Low
Low: usually not concerning.
< 7
Normal
Normal kidney waste clearance.
7 – 20
High
Elevated: may indicate dehydration or reduced kidney function.
> 20

Ranges are a guide: your physician interprets your result alongside your symptoms and history.

Reading a High or Low Result

  • What a higher result can point to

    • Reduced kidney filtration from acute or chronic kidney disease.
    • Dehydration, heat exposure or blood loss reducing blood flow through the kidneys.
    • A diet very high in protein, or heavy use of protein supplements.
    • Bleeding into the stomach or intestine, where blood is absorbed as protein.
    • Heart failure or any condition that lowers blood flow to the kidneys.
    • Corticosteroid or tetracycline treatment increasing protein breakdown.

  • What a lower result can point to

    • Advanced liver disease, since the liver is where urea is made.
    • A diet very low in protein, or prolonged undernutrition.
    • Overhydration or intravenous fluids diluting the blood.
    • Normal pregnancy, in which blood volume expands and filtration increases.
    • Rare inherited disorders of the urea cycle.

These are possibilities, not diagnoses. A single value outside the reference range is interpreted alongside your symptoms, history and other tests: your doctor decides what it means for you.

Limitations & Safety

What this test cannot tell you

  • Urea reflects protein intake, hydration and liver function as well as kidney clearance, so it is never interpreted alone.
  • It changes late: the kidneys can lose a substantial part of their function before urea leaves its usual range.
  • A single reading captures one moment; hydration, a recent high-protein meal or a passing illness can shift it considerably from day to day.

Risks of the blood draw

  • Mild bruising or brief soreness where the needle went in.
  • Occasional lightheadedness, which settles after a few minutes of rest.
  • Bleeding or infection at the site, which is rare with sterile single-use equipment.
Key Points
  • 1Urea is the waste form of protein nitrogen, made by the liver and cleared by the kidneys.
  • 2It is a kidney marker with strong non-kidney influences: diet, hydration, gut bleeding and steroids all move it.
  • 3It is interpreted next to creatinine and eGFR; the relationship between them is more informative than either alone.
  • 4Dehydration is one of the commonest reasons for a mild elevation and is usually reversible.
  • 5Kidney function must fall considerably before urea rises, so an ordinary result does not guarantee healthy kidneys.
Included in health checkups

Blood Urea Nitrogen (BUN) is also part of these health checkups, which add a wider screen in the same appointment.

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Frequently Asked Questions

Everything you need to know about the Blood Urea Nitrogen (BUN) test. Can't find what you're looking for?

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They measure the same substance, expressed differently: BUN reports only the nitrogen portion of the urea molecule, while urea reports the whole molecule. Laboratories in different regions favour one convention or the other, so compare results only within the same reporting style.