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Lymphocyte count Your T cells, B cells and natural killer cells

Also called Absolute lymphocyte count, ALC and Lymphs (Absolute) Often on a standard checkup No fasting needed

The short answer

Lymphocytes are the T cells, B cells and natural killer cells of your immune system.2 Labcorp’s range is 0.7 to 3.1 ×10³/µL.1 Infections, stress and steroids can push the count out of range for a while, so a single result outside it is worth repeating before anything else.2,3

A healthy range
1.0 to 3.1 ×10³/µL. Labcorp’s range starts at 0.7, but the usual definition of a low count is under 1.0.1,2
If yours is low
It’s often temporary, after an infection, stress or steroids.2 If it stays low, find out why. In large studies, low counts went with higher death rates.6,7
If yours is high
A recent viral infection is one cause.3 A count of 5.0 or more that lasts needs a closer look.4

Check your result

Type the number from your report. It stays on this page.

0.7 1 3.2 5
  • Low Under 0.7
  • Low-normal 0.7 to 0.9
  • Normal 1.0 to 3.1
  • High 3.2 to 4.9
  • Very high 5.0 or more

Enter your result to see what it means and what to do next.

Got a result from another lab? Ask Picardo about it. The app explains your results, and a physician can follow up.

Green is the range that’s normal by both Labcorp’s limits and the usual definition of a low count.1,2 The 5.0 line is the B-cell count needed to diagnose chronic lymphocytic leukemia.4 The bar isn’t to scale.

What is a normal lymphocyte count?

Labcorp’s range is 0.7 to 3.1 ×10³/µL. Go by the absolute count, “Lymphs (Absolute)”, because the percentage has no range.1 Other references put the normal adult range at 1.0 to 4.8, so both edges of Labcorp’s range are a gray zone:2

Low Under 0.7 ×10³/µL

Low: worth finding out why

This is low by any definition.1,2 It’s often temporary, after a viral or bacterial infection, a serious illness or steroid treatment.2 If it lasts, the causes a clinician will look for include HIV and other viral infections, undernutrition, heavy drinking, autoimmune disease, some cancers and medicines that suppress the immune system.2

How worried to be

Not an emergency on its own. See a clinician in the next few weeks, or sooner if you keep getting infections or get unusual ones.2

What to do next
  1. 1 Repeat the count once you’ve recovered from any recent illness.2
  2. 2 If it stays low, ask about an HIV test. HIV is one of the most common causes.2
  3. 3 A clinician may also count your lymphocyte types and check your antibody levels.2
Low-normal 0.7 to 0.9 ×10³/µL

In Labcorp’s range, but low by the usual definition

Labcorp won’t flag this, but the usual definition of a low lymphocyte count is under 1.0.1,2 A single result like this is often from a recent infection, stress or steroids, and passes.2

How worried to be

Not a worry on its own. Worth a repeat to see whether it lasts.

What to do next
  1. 1 Repeat the count in a few weeks, once you’re well.2
  2. 2 If it stays under 1.0, raise it with a clinician. Large population studies link counts this low to higher death rates, though that doesn’t show the low count is the cause.6,7
Normal 1.0 to 3.1 ×10³/µL

In the healthy range

You have a normal number of lymphocytes.1,2

How worried to be

Nothing to worry about.

What to do next
  1. 1 Keep this result to compare with future counts. Lymphocyte counts tend to fall with age, so a gradual drift down over the decades is expected.7
High 3.2 to 4.9 ×10³/µL

Above Labcorp’s range: repeat it in a few weeks

Labcorp’s upper limit is lower than many. Other references put it at 4.5 to 4.8, so a mild rise may be normal for you.2,3 When the count is raised, causes include viral infections, whooping cough, allergic-type reactions and not having a working spleen.3

How worried to be

Not urgent. A repeat once any infection has passed is the first step.3

What to do next
  1. 1 Repeat the count in a few weeks.3
  2. 2 If it stays up, a clinician can look at the cells under a microscope: cells of varied shapes and sizes point to a reaction to something, while cells that all look alike raise the question of a clone.3
Very high 5.0 ×10³/µL or higher

Very high: needs a closer look

This can still be a reaction to an infection,3 but it’s also the level where chronic lymphocytic leukemia (CLL) becomes possible. CLL is usually diagnosed when at least 5.0 ×10³/µL of B cells from a single clone stay in the blood for 3 months or more, confirmed by a test called flow cytometry.4 A blood count alone can’t diagnose it.

How worried to be

See a clinician in the next few weeks. Go sooner if you have night sweats, weight loss, fevers or swollen glands, or your other counts are off.3

What to do next
  1. 1 Ask for a repeat count and a look at the cells under a microscope.3
  2. 2 If it stays high, ask whether you need flow cytometry, which shows whether the cells come from one clone.3,4
  3. 3 If there’s a clone but it’s below the CLL threshold, it’s called monoclonal B-cell lymphocytosis (MBL). Each year, about 1% to 2% of people with it go on to need treatment for CLL.4
Complete blood count, $3.75
Results in 2 to 3 days, explained in the app
Order

What is a lymphocyte count?

Only a small share of your lymphocytes are in your blood at any moment. Most live in your lymph nodes, spleen and other tissues, so the count is a snapshot of the traffic, not the whole army.2

About three in four blood lymphocytes are T cells, one in five are B cells and the rest are natural killer cells.2 Together they make up only 20% to 40% of your white cells, so a low lymphocyte count can sit inside a normal total white count.2

What causes a low lymphocyte count?

Often it’s something temporary:2

  • A viral or bacterial infection, including COVID-19 and the flu
  • The stress of a serious illness
  • Steroid medicines

When it lasts, the causes include:2

  • HIV, one of the most common causes
  • Undernutrition, heavy drinking or low zinc
  • Autoimmune disease, such as lupus or rheumatoid arthritis
  • Lymphoma and sarcoidosis
  • Chemotherapy, radiation and medicines that suppress the immune system
  • Rarely, an inherited immune disorder

Does a low lymphocyte count matter?

Over the long run, it can. In a Danish study of more than 108,000 adults followed for about 9 years, those with counts under 1.1 ×10³/µL had about 1.6 times the death rate of those with counts of 1.1 to 3.7, after allowing for smoking, alcohol, weight, diabetes and other factors.7 Deaths from heart disease, cancer and infections were all higher.7 A US survey of more than 31,000 adults found the same pattern, with higher risk at 1.5 or less and higher still at 1.0 or less.6

These are observational links, and a low count may be a sign of illness rather than its cause. But a count that stays low is a reason to look for one.2

What causes a high lymphocyte count?

  • A viral infection3
  • Whooping cough, and some other infections such as syphilis3
  • Allergic-type (hypersensitivity) reactions3
  • Not having a working spleen3
  • A leukemia or lymphoma, such as chronic lymphocytic leukemia (CLL)3

A high count is more likely to be harmless in children than in adults.3

Who should get a lymphocyte count?

A lymphocyte count comes with every complete blood count with a differential, so you may already have one. It’s worth a look if any of these apply to you:

  • You have HIV, or might have been exposed to it.2
  • You take steroids or other medicines that suppress the immune system, or have had chemotherapy or radiation.2
  • You have swollen glands, night sweats, fevers or weight loss you can’t explain.3
  • A past count was high or low and you want to see whether it has moved.

How to get a lymphocyte count test, and what it costs

It comes from the complete blood count, which costs $3.75 through Picardo.

Order the test

Complete blood count

$3.75
Labcorp 005009 · no fasting needed

The test this number comes from.

Order the complete blood count
  • Results in 2 to 3 days, in the app
  • Physician follow-up if you want one
  • Free Labcorp draw, or $75 at home
  • No other fees. HSA and FSA eligible.

It’s also part of the Base Core Annual – Men, Base Core Annual – Women, Heart Health, Brain Health Screening, Pregnancy, Postpartum, Fertility, Thyroid & Autoimmunity and Celiac / GI panels, if you’d rather test more at once.

Already have a result? Ask Picardo about it

Questions people ask

Can stress lower your lymphocyte count?

Yes. Stress responses, such as a serious illness, can lower it for a while, and so can steroid medicines.2 A repeat once things have settled shows whether it was temporary.

Could a high lymphocyte count be leukemia?

It could, which is why a count that stays at 5.0 or more gets a closer look.4 But small clones of B cells are common with age. In a Minnesota study that screened more than 10,000 adults aged 40 or older, 17% had one, rising from 4% in their 40s to 42% at 90 and over. Most clones were tiny: people with them lived as long as people without, and as a group, people with a clone developed a blood cancer at about 0.5% a year.5

What is the neutrophil-to-lymphocyte ratio?

Your neutrophil count divided by your lymphocyte count, used as a marker of inflammation. In a Dutch study of about 8,700 older adults, those with higher ratios had higher death rates, even after allowing for age, smoking, diabetes and past heart disease or cancer.8 It isn’t a diagnosis on its own.

Do lymphocytes go down with age?

Yes, on average.7 In a large Danish study, people with low counts were typically about 10 years older than the rest, with a median age of 68 against 58.7

Does a low lymphocyte count mean a weak immune system?

A brief dip after an illness doesn’t. A count that stays low can, and recurring or unusual infections are the main sign. A clinician can then check which types of lymphocytes are low and how well you make antibodies.2

Often checked alongside

White blood cell count
Cells that fight infection
Neutrophil count
White cells that fight bacterial infections
Platelet count
Cells that help blood clot
Hemoglobin
Carries oxygen; low levels mean anemia

Test details

Labcorp test
Complete Blood Count (CBC) With Differential, Reflex to Peripheral Smear Review, 005009
LOINC
731-0
Sample
Blood
Fasting
Not needed
Typical lab range
0.7 to 3.1 ×10³/µL
Units
×10³/µL, which Labcorp prints as x10E3/uL. It’s the same number as ×10⁹/L.

Sources

  1. 1 Labcorp. CBC with differential/platelet, test 005009: sample patient reports (female, age 46; reported September 15, 2026). Burlington, NC: Labcorp; 2026. Accessed October 28, 2026. files.labcorp.com/testmenu-d8/sample_reports/005009.pdf
  2. 2 Dale DC. Lymphocytopenia. Merck Manual Professional Edition. Reviewed February 2025; updated April 2026. Accessed October 28, 2026. www.merckmanuals.com/professional/hematology-and-oncology/leukopenias/lymphocytopenia
  3. 3 Riley LK, Rupert J. Evaluation of patients with leukocytosis. Am Fam Physician. 2015;92(11):1004–1011. pubmed.ncbi.nlm.nih.gov/26760415/
  4. 4 Hallek M, Cheson BD, Catovsky D, et al. iwCLL guidelines for diagnosis, indications for treatment, response assessment, and supportive management of CLL. Blood. 2018;131(25):2745–2760. doi.org/10.1182/blood-2017-09-806398
  5. 5 Slager SL, Parikh SA, Achenbach SJ, et al. Progression and survival of MBL: a screening study of 10 139 individuals. Blood. 2022;140(15):1702–1709. doi.org/10.1182/blood.2022016279
  6. 6 Zidar DA, Al-Kindi SG, Liu Y, et al. Association of lymphopenia with risk of mortality among adults in the US general population. JAMA Netw Open. 2019;2(12):e1916526. doi.org/10.1001/jamanetworkopen.2019.16526
  7. 7 Warny M, Helby J, Nordestgaard BG, Birgens H, Bojesen SE. Incidental lymphopenia and mortality: a prospective cohort study. CMAJ. 2020;192(2):E25–E33. doi.org/10.1503/cmaj.191024
  8. 8 Fest J, Ruiter TR, Groot Koerkamp B, et al. The neutrophil-to-lymphocyte ratio is associated with mortality in the general population: the Rotterdam Study. Eur J Epidemiol. 2019;34(5):463–470. doi.org/10.1007/s10654-018-0472-y

Updated 28 Oct 2026.

This is general health information, not medical advice: talk to your clinician about your results and before changing any treatment.