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Hematology

Leukocyte differential: lymphocytes, smoking and what a deviation means

Lymphocytes are one of the five kinds of white blood cells, and according to the NVKC they play an important role mainly in defence against viruses. According to the NVKC, all white blood cells are made in the bone marrow and protect the body against infections.

According to the NVKC, a raised lymphocyte count is usually the result of an infection with a virus and sometimes with a bacterium, and a low lymphocyte count is uncommon. Only a blood test shows how many lymphocytes and other white blood cells there are.

Certe uses 0.8 to 3.2 × 10⁹/L lymphocytes and 1.8 to 7 × 10⁹/L neutrophils for men older than 18.

Doctor's Assessment Included

The leukocyte differential counts the white blood cells, the cells of the immune system, by type: neutrophils, lymphocytes, monocytes, eosinophils and basophils. Each type has its own normal value, which can differ between laboratories.

  • For adults, Star-SHL uses 1.8 to 7.3 × 10⁹/l neutrophils and 1.5 to 4.0 × 10⁹/l lymphocytes; for everyone older than 15, Unilabs uses 1.5 to 7.5 × 10⁹/l neutrophils and 1.0 to 3.5 × 10⁹/l lymphocytes.
  • When the leukocyte differential is abnormal, Star-SHL also examines the blood under the microscope.

Leukocyte Differential: what this test measures

The leukocyte differential measures the count of each of the five kinds of white blood cells. Certe has a separate test for each kind, with limits per age that are the same for men and women older than 18.

Leukocyte Differential: why this value matters

According to the NVKC, a leukocyte differential can show whether the immune system is sufficiently able to fight infections. According to the NVKC, the lymphocyte and neutrophil counts are especially important for a well-working immune system.

Leukocyte Differential: 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.
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

Leukocyte Differential: when is testing worthwhile?

According to the NVKC, lymphocytes in the leukocyte differential are usually measured when a doctor suspects an infection or inflammation, and sometimes to look for a certain kind of leukaemia.

Leukocyte Differential: symptoms of a high or low value

Low Levels

Medicines, especially painkillers and antibiotics, are usually the cause, according to the NVKC, when the leukocyte differential shows too few neutrophils. According to the NVKC, serious infections such as typhoid and hepatitis, and ionising radiation, can also lower the neutrophil count.

High Levels

According to the NVKC, the lymphocyte count in the leukocyte differential can be raised in certain kinds of leukaemia, especially in older people. According to a 2015 review in American Family Physician, smoking is on the list of non-malignant causes of a raised white blood cell count, alongside certain medicines, obesity and chronic inflammatory conditions, among others.

Leukocyte Differential: causes of a low or high value

What lowers the value

  • Medicines

    A low neutrophil count is usually caused by medicines, especially painkillers and antibiotics.

  • Black African descent

    People of Black African descent tend to have lower white cell and neutrophil counts.

  • Few lymphocytes (uncommon)

    A low lymphocyte count is uncommon and can be caused by HIV infection, malnutrition, vitamin deficiencies or loss of lymphocytes through the gut.

What raises the value

  • Bacterial infection or inflammation

    In a bacterial infection and other inflammation, such as serious injuries and burns, the neutrophil count can rise.

  • Viral infection

    A raised lymphocyte count is usually caused by a viral infection.

  • Allergy or parasites

    A raised eosinophil count usually points to a parasitic infection or an allergic reaction such as hay fever, asthma or food allergy.

  • Exercise, stress, smoking, obesity or medicines

    Exercise, emotional stress, smoking, obesity and some medicines, such as corticosteroids, can raise the white cell count.

  • Blood cancer

    In some types of blood cancer the neutrophil count can be raised.

Leukocyte Differential: lifestyle and this value

With an abnormal leukocyte differential, the GP is the next step. According to a 2015 review in American Family Physician, for a raised white blood cell count recent stressful events, medication use and smoking status should be noted, among other things.

Leukocyte Differential: frequently asked questions

What are T cells, B cells and NK cells?

According to the NVKC, T cells, B cells and NK cells (natural killer cells) are the three kinds of lymphocytes, one of the five kinds of white blood cells in the leukocyte differential.

When is a raised lymphocyte count called lymphocytosis?

According to a 2015 review in American Family Physician, lymphocytosis is present when lymphocytes in the leukocyte differential make up more than 40% of the white blood cells or the absolute count is above 4.5 × 10⁹ per litre. According to that article, lymphocytosis is more likely to be benign in children than in adults.

Leukocyte Differential: sources

  1. NVKC, Alles over testen: Neutrofiele granulocyten, allesovertesten.nl, geraadpleegd 2026-10-06 (retrieved 2026) allesovertesten.nl
  2. Riley LK, Rupert J. Evaluation of Patients with Leukocytosis. Am Fam Physician 2015;92(11):1004-1011. (retrieved 2026) aafp.org
  3. NVKC, Alles over testen: Lymfocyten, allesovertesten.nl, geraadpleegd 2026-10-06 (retrieved 2026) allesovertesten.nl
  4. NVKC, Alles over testen: Eosinofiele granulocyten, allesovertesten.nl, geraadpleegd 2026-10-06 (retrieved 2026) allesovertesten.nl

Tests with related values

These panels measure values from the same category as this marker.

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Leukocyte Differential

€13,-