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Kidney

Urea (BUN) in women: the limits by age and what the value says

According to MedlinePlus, the kidneys remove urea from the blood, a waste product left when the body breaks down proteins, and pass it out in the urine. According to MedlinePlus, how much urea the blood holds can vary by sex and usually increases with age.

According to MedlinePlus, a urea above normal may point to kidneys that are not working well, or to dehydration, and according to the Cleveland Clinic a low urea can be due to, among other things, too much water in the body. A blood test is the only way to know the urea.

Star-SHL uses 2.5 to 7.0 mmol/l for women aged 19 to 50 inclusive and 2.9 to 9.4 mmol/l for women 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:

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
2,2 13,9 mmol/l
Reference ranges by group, in mmol/l
Female · 6–12 years 2,4–7,3 mmol/l
2,4 7,3
Female · 13–18 years 2,2–6,9 mmol/l
2,2 6,9
Female · 19–50 years 2,5–7 mmol/l
2,5 7
Female · 51–65 years 2,9–9,4 mmol/l
2,9 9,4
Female · 66–80 years 3,1–11,8 mmol/l
3,1 11,8
Female · 81 years and older 3,6–13,9 mmol/l
3,6 13,9
2,2 13,9 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
Star-shl · Female · 19–50 years 2.5–7.0 mmol/l
2.5 7
Star-shl · Female · 51–65 years 2.9–9.4 mmol/l
2.9 9.4
Star-shl · Female · 66–80 years 3.1–11.8 mmol/l
3.1 11.8
Star-shl · Female · 81 years and older 3.6–13.9 mmol/l
3.6 13.9
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 15.29 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

Urea in the blood is measured in mmol/l, and Star-SHL gives women a limit of their own per age group: 3.1 to 11.8 mmol/l from 66 to 80 inclusive and 3.6 to 13.9 mmol/l above 80.

Urea (BUN): why this value matters

Urea matters because, according to MedlinePlus, kidney disease can lead to a build-up of this waste in the blood, possibly resulting in high blood pressure, anaemia or heart disease.

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 can be useful at a risk of kidney problems, such as diabetes, high blood pressure or a family history of kidney problems.

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

Low Levels

According to the Cleveland Clinic, a low urea can go with too much water in the body, a small body type or too little protein in the diet.

High Levels

According to the Cleveland Clinic, a high urea may point to kidneys working less well, and also to dehydration, bleeding in the gastrointestinal tract or a blockage in the urinary system. According to the Cleveland Clinic, tiredness, itching and swelling around the feet and ankles can be symptoms of late-stage kidney disease.

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

According to the Cleveland Clinic, an abnormal urea need not mean chronic kidney disease, because sometimes drinking more or a change in diet is what is needed. Discuss the result with your GP.

Urea (BUN): frequently asked questions

Do women have a lower urea than men?

Star-SHL uses 2.5 to 7.0 mmol/l for women aged 19 to 50 inclusive and 2.9 to 8.6 mmol/l for men of that age; according to MedlinePlus, urea can vary by sex.

Urea (BUN): sources

  1. 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
  2. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  4. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  5. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  6. MedlinePlus, BUN (Blood Urea Nitrogen), medlineplus.gov, geraadpleegd 2026-10-18 (retrieved 2026) medlineplus.gov
  7. Cleveland Clinic Health Library, Blood Urea Nitrogen (BUN) Test, my.clevelandclinic.org, geraadpleegd 2026-10-18 (retrieved 2026) my.clevelandclinic.org

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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)
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Urea (BUN)

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