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Urea (BUN)

Urea (BUN) in men: age, kidney risk and the value

According to the Cleveland Clinic, when protein from food is broken down, the liver forms urea, a waste product that reaches the kidneys through the blood. Through the kidneys, it passes from the blood into the urine.

According to the Cleveland Clinic, a high urea may suggest kidneys working less well, while ageing can also raise the value. Because the early stages of chronic kidney disease usually cause no symptoms according to the Cleveland Clinic, only a blood test shows the urea.

Star-SHL uses 2.9 to 8.6 mmol/l for men aged 19 to 50 inclusive and 3.2 to 9.8 mmol/l for men aged 51 to 65 inclusive.

Doctor's Assessment Included

Urea is a waste product formed when protein is broken down, which the kidneys filter out of the blood. According to MedlinePlus, a high urea may point to kidneys not working well, but dehydration and eating a lot of protein can also raise the value.

Certe uses 2.5 to 7.5 mmol/l for urea above 18, Diagnostiek voor U 2.5 to 6.4 mmol/l and Unilabs 2.5 to 6.4 mmol/l from 18 to 60.
Star-SHL uses bands for urea by age and sex, such as 2.9 to 8.6 mmol/l in men and 2.5 to 7.0 mmol/l in women, both aged 19 to 50 inclusive.
According to the Cleveland Clinic, a low urea is not common and can be due to, among other things, too little protein or liver disease.

Reference Ranges

See the value that applies to you:

Age years

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Your reference range

mmol/l

2,7 14,2 mmol/l

Reference ranges by group, in mmol/l
Sex	Age	Reference range (mmol/l)	Relative scale
Male	· 6–12 years	2,8–7,1 mmol/l	2,8 7,1
Male	· 13–18 years	2,7–7,6 mmol/l	2,7 7,6
Male	· 19–50 years	2,9–8,6 mmol/l	2,9 8,6
Male	· 51–65 years	3,2–9,8 mmol/l	3,2 9,8
Male	· 66–80 years	3,6–11,8 mmol/l	3,6 11,8
Male	· 81 years and older	4,3–14,2 mmol/l	4,3 14,2

2,7 14,2 mmol/l

Source: NVKC Reference population: Dutch general-practice population (NUMBER, n = 7,574,327)

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Urea (BUN): what Dutch laboratories use

Reference ranges by group, in mmol/l
Laboratory	Group	Reference value (mmol/l)	Relative scale
Star-shl	· Male · 19–50 years	2.9–8.6 mmol/l	2.9 8.6
Star-shl	· Male · 51–65 years	3.2–9.8 mmol/l	3.2 9.8
Star-shl	· Male · 66–80 years	3.6–11.8 mmol/l	3.6 11.8
Star-shl	· Male · 81 years and older	4.3–14.2 mmol/l	4.3 14.2
Unilabs	· Everyone · 18–60 years	2.5–6.4 mmol/l	2.5 6.4
Unilabs	· Everyone · 60 years and older	2.9–7.5 mmol/l	2.9 7.5
Certe	· Everyone · 18 years and older	2.5–7.5 mmol/L	2.5 7.5
Diagnostiek voor U	· Everyone	2.5–6.4 mmol/L	2.5 6.4

0 15.62 mmol/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

Urea (BUN): what this test measures

A urea test measures in mmol/l the urea in the blood, and Star-SHL lets the limit for men rise with age: 3.6 to 11.8 mmol/l from 66 to 80 inclusive and 4.3 to 14.2 mmol/l above 80.

Urea (BUN): why this value matters

Urea matters because, according to MedlinePlus, being over the age of 60 is one of the reasons someone may be at risk of kidney problems, alongside diabetes, high blood pressure and smoking, among others.

Urea (BUN): how the blood test works

Referral: No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw: A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test: Kidney Function · €69,- · Complete Metabolic Panel · €149,-
Where: 650+ draw sites run by independent laboratories across the Netherlands. Draw sites

Urea (BUN): when is testing worthwhile?

According to MedlinePlus, a urea test may be done as screening at a risk of kidney problems, because early kidney disease usually has no signs or symptoms.

Urea (BUN): symptoms of a high or low value

Low Levels

According to the Cleveland Clinic, a urea below the limit is uncommon and can be due to liver disease, too little protein or too much water in the body.

High Levels

According to the Cleveland Clinic, ageing, a heart attack, stress and certain medicines such as carbamazepine, methotrexate and tetracycline can raise urea, alongside kidneys working less well. According to the Cleveland Clinic, if creatinine is high as well as urea, kidney failure is likely.

Urea (BUN): causes of a low or high value

What lowers the value

Not eating enough protein

A lack of protein in the diet can give a lower-than-normal urea.
Malnutrition

Malnutrition is a possible reason for a lower-than-normal urea.
Too much water in the body (overhydration)

Having too much water in the body is a possible cause of low urea.
Liver disease

Liver disease is a possible cause of low urea.

What raises the value

Kidneys not working well

Higher-than-normal urea levels may be a sign that the kidneys are not working well.
Dehydration

Even with kidneys working properly, urea can rise from dehydration.
Eating a lot of protein

Eating a lot of protein is a possible cause of high urea with kidneys working properly.
Bleeding in the gastrointestinal tract

Gastrointestinal bleeding is on the list of possible causes of high urea.
Certain medicines

Certain medicines, including carbamazepine, methotrexate and tetracycline, can raise urea.

Urea (BUN): lifestyle and this value

Discuss an abnormal urea with your GP and mention any medicines you take, because according to the Cleveland Clinic certain medicines can raise the value.

Urea (BUN): frequently asked questions

Does urea rise with age?

According to MedlinePlus, urea usually increases with age, and Star-SHL raises its limits for men and women from age 19 with each age group.

Urea (BUN): sources

den Elzen WPJ, Brouwer N, Thelen MH, Le Cessie S, Haagen I-A, Cobbaert CM. NUMBER: standardized reference intervals in the Netherlands using a 'big data' approach. Clin Chem Lab Med 2018;57(1):42-56. (retrieved 2026) doi.org
Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
MedlinePlus, BUN (Blood Urea Nitrogen), medlineplus.gov, geraadpleegd 2026-10-18 (retrieved 2026) medlineplus.gov
Cleveland Clinic Health Library, Blood Urea Nitrogen (BUN) Test, my.clevelandclinic.org, geraadpleegd 2026-10-18 (retrieved 2026) my.clevelandclinic.org

Test Products

This marker is included in the following test panels.

Health check

Kidney Function

Creatinine, eGFR, and BUN: key kidney markers.

Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate)

€69,-

Heart and blood vessels

Complete Metabolic Panel

Comprehensive metabolic panel: electrolytes, kidney, liver, glucose, HbA1c, and protein.

HbA1c (Glycated Hemoglobin) ALT (Alanine Aminotransferase) Calcium ALP (Alkaline Phosphatase) AST (Aspartate Aminotransferase) Bilirubin (Total) Urea (BUN) Creatinine eGFR (Estimated Glomerular Filtration Rate) Glucose (Fasting) Bicarbonate Chloride Sodium Potassium Albumin Total Protein Bilirubin (Direct) Bilirubin (Indirect)

€149,-