Blood count and blood group · Blood

Lymphocytes

The white blood cells of the specific immune defense against viruses; raised in viral infections, low with stress, medicines or illness.

At a glance

Measured in blood
In 6 test panels
No special preparation

Explanation

Lymphocytes: what is measured?

The analysis counts the number of lymphocytes per liter of blood, as part of the white blood cell differential. Lymphocytes are one of the five types of white blood cells and form the specific immune defense: T cells and NK cells clear virus-infected cells, B cells make antibodies. In adults they make up about a fifth to a third of all white blood cells; in children the share is higher. The count is assessed alongside the total number of white blood cells and the other types.

What can it detect?

Viral infections (usually a raised count), such as glandular fever (mononucleosis)
Weakened immune defense due to stress, corticosteroids, chemotherapy, malnutrition or an HIV infection (low count)
Rarely: chronic lymphocytic leukemia or a lymphoma (lymph node cancer), mainly at an older age (persistently and strongly raised count)

Result

What does the result mean?

Lymphocytes too high

A raised lymphocyte count (lymphocytosis) is usually caused by a viral infection, such as glandular fever (mononucleosis), a cytomegalovirus infection, a common cold or shortly after a vaccination; whooping cough and some other bacterial infections also raise the count. Smoking and a removed spleen give a slightly raised count. The count falls by itself after a few weeks once the infection is over. Rarely: chronic lymphocytic leukemia (CLL), a slowly progressing blood disease that often needs no treatment for years, mainly with a persistently and clearly raised count without infection in people over 60. The GP then has the blood examined further and consults a hematologist.

Lymphocytes too low

A low lymphocyte count (lymphopenia) is often temporary: during an acute infection, after surgery, with fever or with physical or psychological stress, the body makes cortisol, which makes lymphocytes temporarily disappear from the blood. Medicines such as prednisone and other corticosteroids, chemotherapy, immunosuppressants and radiotherapy lower the count. Other causes are malnutrition, excessive alcohol use, an autoimmune disease such as lupus, kidney disease, an HIV infection and old age. With a strongly low count, the defense against viruses and fungi is reduced and infections occur more often or are more severe. A slightly low count without symptoms usually has no meaning.

After an abnormal result

With a slightly abnormal count without symptoms, the GP repeats the measurement after a few weeks, once any infection is over. With a persistently or strongly raised count, the GP has the blood examined under the microscope and, if needed, the types of lymphocytes further characterized (lymphocyte subtyping), and consults a hematologist if there are signs of a blood disease. With a persistently low count, the GP looks at medicines, nutrition and underlying diseases and tests for HIV if needed.

Reliability

How reliable is the test?

The differential is performed accurately by the blood cell counter; with abnormalities, the laboratory looks under the microscope. However, the lymphocyte count fluctuates strongly with infections, stress, time of day and medicines, which makes it of limited use as a single value. The count gains meaning in combination with symptoms, the total number of white blood cells, the other types of white blood cells, the hemoglobin and the platelets. A strongly abnormal blood count can rarely point to a blood disease; the GP then investigates this further.

What can affect the result?

A viral infection or vaccination in the weeks before the blood draw raises the count temporarily; acute stress, fever or surgery lowers it temporarily.
Corticosteroids (prednisone), chemotherapy and immunosuppressive medicines lower the count strongly.
In children, higher counts are normal; reference values differ by age and laboratory.
When blood is in transit to the laboratory for a long time, the differential is less reliable because the cells change shape.

Who it is for

Who is the test useful for?

Useful for

Useful with symptoms that point to an infection (fever, sore throat, swollen lymph nodes, prolonged tiredness after an infection), with recurring or unusual infections, for monitoring during immunosuppressive medicines and as part of an extended blood count. In healthy adults without symptoms, a slightly abnormal count is usually temporary and not significant.

How common is it?

A temporarily raised lymphocyte count due to a viral infection is very common, especially in children and young adults. A persistently raised count without infection is rare and occurs mainly in older people.

Drawbacks and risks

A slightly abnormal lymphocyte count is almost always temporary in healthy people; without a repeat measurement, the result can cause unnecessary worry about a blood disease.

Get tested

Lymphocytes: test panels

Lymphocytes is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
Complete Blood Count (CBC)
Complete Blood Count Extended; standard blood count plus detailed white blood cell analysis.
€ 27,00
Blood draw
PhenoAge
PhenoAge Biological Age Test; determine your biological age with 9 standard blood values.
€ 85,00
Blood draw
InsideTracker
InsideTracker Blood Analysis: analyze 48 biomarkers for complete health optimization and personalized recommendations.
€ 335,00
Blood draw
Supplemental: Testosterone Replacement Therapy (TRT)
Complete hormonal analysis with testosterone, DHEA-S, thyroid, blood count, liver function, kidney function, lipids, glucose, HbA1c, insulin, hs-CRP, vitamin D and ferritin.
€ 335,00
Blood draw
Whoop (Advanced Labs)
Comprehensive blood analysis with biomarkers that integrates directly with your WHOOP wearable for optimal performance and recovery.
€ 385,00
Fingerstick
Full blood count with differential (CBC) (finger-prick)
Full blood count including haemoglobin, platelets and a white cell differential.
€ 27,00

How reliable is the test?

Lymphocytes