Lab result explainedBlood count (CBC)Last updated November 11, 2026

Absolute monocytes (mono abs): normal range, what a high or low monocyte count means

Absolute monocyte count (Mono abs) · Complete blood count (CBC) with differential · reported in ×10³/µL (K/µL, thousand per microliter) or cells/µL; 0.8 ×10³/µL = 800 cells/µL = 0.8 ×10⁹/L

The absolute monocyte count ("mono abs" or "monocytes absolute" on a CBC with differential) is the number of monocytes in a microliter of blood, calculated by multiplying the total white cell count by the monocyte percentage. Monocytes are the largest white cells; they circulate for a day or two and then move into tissues, where they become macrophages and dendritic cells that engulf microbes and dead cells, present antigens to lymphocytes and help repair tissue. In adults the normal range is about 0.2 to 0.8 ×10³/µL, which is 200 to 800 cells per microliter, or 2 to 10 percent of white cells. Laboratories differ slightly.

A high absolute monocyte count (monocytosis, generally above 0.8 to 1.0 ×10³/µL) is common and most often means your body is dealing with, or recovering from, an infection or an inflammatory process. Chronic infections such as tuberculosis and endocarditis, autoimmune diseases, inflammatory bowel disease, smoking and obesity all raise it, as does the recovery phase after any acute illness or after chemotherapy. A sustained count above 1.0 with no explanation, particularly in someone over 60 with other abnormal counts, raises the possibility of chronic myelomonocytic leukemia (CMML) or another bone marrow disorder, which is why persistent monocytosis is investigated rather than ignored.

A low absolute monocyte count (monocytopenia, below about 0.2 ×10³/µL) is less often searched for but does matter: it is seen during acute infections, with corticosteroid treatment, after chemotherapy and in hairy cell leukemia, where a near-absent monocyte count is a classic clue. This page explains the ranges, the common and important causes of high and low results, what to read the count with and what usually happens next.

Mono abs at a glance

What it is: the number of monocytes per microliter of blood, calculated from the total white cell count and the differential; cells that become tissue macrophages and clear microbes, debris and dead cells.
Normal (adults): about 0.2–0.8 ×10³/µL (200–800 cells/µL), or 2–10 percent of white cells. Some labs print 0.1–1.0 or 0.3–0.9. Labs differ; children and newborns run higher.
High (monocytosis): above 0.8–1.0 ×10³/µL. Common causes are acute or chronic infection (including recovery), inflammatory and autoimmune disease, smoking, obesity and steroid withdrawal; a persistent count above 1.0 with no cause needs evaluation for CMML and other marrow disorders.
Low (monocytopenia): below about 0.2 ×10³/µL. Causes include acute infection and sepsis, corticosteroids, chemotherapy, aplastic anemia, hairy cell leukemia and rare GATA2 deficiency.
A single mildly high or low result during an illness usually just needs a repeat when well; the trend and the other cell counts matter more than one number.
Next step: repeat in 4 to 8 weeks when well; if monocytosis persists, a blood smear, inflammatory markers, infection screen and, above 1.0 for more than 3 months, hematology review with flow cytometry and possibly a bone marrow test.

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What Mono abs measures

Monocytes are made in the bone marrow from the same precursor as neutrophils, under the influence of macrophage colony-stimulating factor and GM-CSF. They circulate for one to three days, then enter tissues to become macrophages (Kupffer cells in the liver, alveolar macrophages in the lung, osteoclasts in bone, microglia in the brain) and dendritic cells. In the blood they exist as classical (about 85 percent), intermediate and non-classical subsets; the intermediate and non-classical subsets rise in chronic inflammation and cardiovascular disease, though routine CBCs do not separate them.

The analyzer identifies monocytes by their size, light scatter and nuclear characteristics as part of the five-part differential and reports a percentage and an absolute number; the absolute number is the percentage multiplied by the total white cell count. Monocytes are the hardest normal white cell for an analyzer to distinguish, because large reactive lymphocytes, immature granulocytes and blasts can be miscounted as monocytes, so an unexpectedly high result is usually confirmed by a technologist's review of a stained smear. Units of 0.6 ×10³/µL, 0.6 K/µL, 0.6 ×10⁹/L and 600 cells/µL are all the same value.

Monocytes rise within a day or two of an acute infection or tissue injury and stay up during the recovery phase, often peaking as neutrophils are returning to normal; after chemotherapy they are the first white cells to recover, so a rising monocyte count is a welcome sign that the marrow is coming back. Corticosteroids lower the count within hours, intense exercise and adrenaline raise it briefly, and smokers and people with obesity run higher baseline counts. Because the count varies with these factors, a single mildly abnormal result is interpreted in context and repeated.

Normal range for Mono abs

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

Group	Typical range (×10³/µL (K/µL, thousand per microliter) or cells/µL; 0.8 ×10³/µL = 800 cells/µL = 0.8 ×10⁹/L)	Notes
Adults, normal	0.2–0.8 ×10³/µL (200–800 cells/µL); 2–10 percent of white cells	Some labs print 0.1–1.0, 0.3–0.9 or up to 12 percent. Labs differ; use the printed range.
Children	About 0.2–1.0 ×10³/µL	Percentages are similar to adults, but higher total white counts in young children give higher absolute numbers.
Newborns and infants	Up to about 1.5–2.0 ×10³/µL in the first weeks	Falls toward childhood values over the first months of life.
Mild monocytosis	0.8–1.0 ×10³/µL (800–1,000 cells/µL)	Very common; infection or its recovery, inflammation, smoking, obesity. Usually repeated when well rather than investigated.
Monocytosis	Above 1.0 ×10³/µL (over 1,000 cells/µL)	Chronic infection (tuberculosis, endocarditis), autoimmune disease, inflammatory bowel disease, recovery from neutropenia, splenectomy, malignancy. Persisting beyond 3 months needs a hematology opinion.
Threshold used for chronic myelomonocytic leukemia	Above 0.5 ×10³/µL and above 10 percent of white cells, persisting more than 3 months, with reactive causes excluded	2022 World Health Organization criteria (earlier criteria used 1.0); the diagnosis also requires marrow findings or a clonal genetic abnormality.
Low (monocytopenia)	Below 0.2 ×10³/µL (under 200 cells/µL)	Acute infection, corticosteroids, chemotherapy, hairy cell leukemia, aplastic anemia, GATA2 deficiency.
Severe monocytopenia	Below 0.1 ×10³/µL, often 0	Near-absent monocytes with low neutrophils, an enlarged spleen and fatigue is the classic picture of hairy cell leukemia.

High absolute monocytes (monocytosis)

A high mono abs usually means the immune system has been activated for more than a few days. Monocytes are recruited in the later, clearing-up phase of infection and inflammation, so the count climbs during recovery from pneumonia, a viral illness or an abscess and stays up for a week or two after you feel better. Chronic infections that smolder for weeks (tuberculosis, infective endocarditis, syphilis, brucellosis, some fungal infections) are classic causes of a sustained rise, as are chronic inflammatory conditions: rheumatoid arthritis, lupus, sarcoidosis, Crohn's disease and ulcerative colitis.

Lifestyle factors matter too. Smokers have monocyte counts about 10 to 25 percent higher than non-smokers, and people with obesity run higher counts because fat tissue continuously recruits and activates monocytes; both are also associated with the inflammatory monocyte subsets linked to atherosclerosis. Corticosteroid withdrawal, splenectomy, stress and strenuous exercise cause short-lived rises. In most of these situations the count is 0.8 to 1.5 ×10³/µL and other counts are normal.

The concern is a monocytosis that persists for months with no reactive cause, particularly in someone over 60. Chronic myelomonocytic leukemia (CMML) is defined by a persistent monocyte count above 0.5 ×10³/µL making up more than 10 percent of white cells, with marrow dysplasia or a clonal mutation. Monocytosis also occurs in acute myeloid leukemia with monocytic features, in myelodysplastic syndromes, in Hodgkin and some non-Hodgkin lymphomas, and with some solid cancers. The pointers are a count above 1.0 for more than 3 months, unexplained anemia or low platelets, immature cells on the smear, an enlarged spleen, night sweats or weight loss.

Common causes

Recovery from acute infection or neutropenia
Monocytes peak as an infection resolves and are the first white cells to return after chemotherapy or a viral marrow suppression; counts of 1.0 to 1.5 ×10³/µL for a week or two in this setting are expected and need no action.
Chronic bacterial, fungal and protozoal infection
Tuberculosis, infective endocarditis, syphilis, brucellosis, histoplasmosis, leishmaniasis and malaria produce a sustained monocytosis, usually with fever, sweats, raised CRP and ESR, and anemia of chronic disease.
Autoimmune and inflammatory disease
Rheumatoid arthritis, systemic lupus, sarcoidosis, vasculitis, Crohn's disease and ulcerative colitis raise the count in proportion to disease activity; in inflammatory bowel disease it tracks with flares.
Smoking and obesity
Both raise the baseline count modestly and shift monocytes toward the inflammatory CD16-positive subsets; counts fall over months after quitting or losing weight.
Chronic myelomonocytic leukemia (CMML)
A marrow neoplasm of older adults (median age about 70) with persistent monocytes above 0.5 ×10³/µL and more than 10 percent of white cells, often with anemia, low platelets, an enlarged spleen and mutations in TET2, SRSF2 or ASXL1. The main reason unexplained monocytosis lasting over 3 months is referred.
Other blood cancers
Acute myeloid leukemia with monocytic differentiation, myelodysplastic syndromes, juvenile myelomonocytic leukemia in young children, Hodgkin lymphoma and some non-Hodgkin lymphomas; usually with other abnormal counts or blasts on the smear.
Solid cancers
Breast, ovarian, kidney, lung and gastrointestinal cancers can raise monocytes as part of a tumor-related inflammatory response; a high monocyte-to-lymphocyte ratio is an adverse prognostic marker in several cancers.
Splenectomy or a non-functioning spleen
The spleen normally holds a reserve of monocytes; after its removal or in sickle cell disease the circulating count is persistently higher.
Corticosteroid withdrawal, stress and exercise
Steroids suppress monocytes, so stopping them produces a rebound; adrenaline from stress or hard exercise mobilizes monocytes for a few hours.
Pregnancy and the postpartum period
Monocyte counts rise modestly through pregnancy as part of the general white cell increase and return to baseline within weeks of delivery.

Symptoms that can go with it

Often none; a mild rise is usually an incidental finding
Lingering fatigue, low-grade fever, night sweats or weight loss with chronic infection or inflammation
Joint pain and morning stiffness, rashes or mouth ulcers with autoimmune disease
Abdominal pain, diarrhea or blood in the stool with inflammatory bowel disease
Cough lasting weeks, sweats and weight loss with tuberculosis or fungal infection
A heart murmur with fevers and fatigue, which can signal endocarditis
Fullness or discomfort under the left ribs, easy bruising, breathlessness or recurrent infections if the marrow is involved

Low absolute monocytes (monocytopenia)

A low mono abs, below about 0.2 ×10³/µL, is most often temporary and explained by something on the same report or in the recent history. Early in a severe acute infection or sepsis, monocytes move out of the blood into tissue and the count can fall to near zero for a day or two before rebounding; corticosteroids (prednisone, dexamethasone, hydrocortisone) do the same within hours of a dose; and chemotherapy, radiotherapy and some immunosuppressants reduce monocytes along with neutrophils. In each case the count recovers once the cause has passed.

A persistently low or absent monocyte count in someone who is not on steroids and not acutely ill is a more specific clue. Hairy cell leukemia, a rare and treatable B-cell cancer, characteristically produces a near-absent monocyte count with low neutrophils, anemia, an enlarged spleen and a 'dry tap' on marrow aspiration. Aplastic anemia and marrow infiltration lower all cell lines. Rarely, an inherited GATA2 deficiency (MonoMAC syndrome) causes a profound lack of monocytes, B cells and NK cells with recurrent mycobacterial, fungal and HPV infections in young adults. Isolated monocytopenia with every other count normal and no symptoms is usually not significant.

Common causes

Acute infection and sepsis
Monocytes leave the blood for the site of infection in the first 24 to 48 hours; a very low count at presentation with a high neutrophil count and high CRP suggests a serious bacterial infection, and the count rebounds with recovery.
Corticosteroid medication
Prednisone, dexamethasone and other glucocorticoids cause monocytes to fall within 4 to 6 hours of a dose, recovering within a day; long-term steroid users often run low counts.
Chemotherapy, radiotherapy and immunosuppressants
Marrow-suppressing drugs lower monocytes alongside neutrophils; the monocyte count is usually the first to recover and is watched as an early sign of marrow regeneration.
Hairy cell leukemia
A rare chronic leukemia of middle-aged and older adults in which monocytes are nearly absent, neutrophils and platelets are low, the spleen is enlarged and the characteristic 'hairy' cells are seen on the smear and confirmed by flow cytometry; it responds very well to treatment.
Aplastic anemia and marrow infiltration
Failure or replacement of the bone marrow lowers all cell lines; anemia and low platelets are usually the dominant findings.
GATA2 deficiency (MonoMAC syndrome)
An inherited disorder presenting in adolescence or young adulthood with monocytes close to zero, very low B and NK cells, and unusual infections (non-tuberculous mycobacteria, severe warts, fungal infections); it carries a high risk of progression to myelodysplasia or leukemia.
HIV infection and some viral illnesses
Advanced HIV, and acute infections such as influenza and dengue, can transiently lower monocytes along with lymphocytes.

Symptoms that can go with it

Usually none from the low count itself
Fever, chills and feeling very unwell if it accompanies a severe infection
Fatigue, frequent infections, easy bruising or a feeling of fullness under the left ribs, which together suggest a marrow or spleen problem
Recurrent unusual infections (persistent warts, mycobacterial or fungal infections) in a young adult, pointing to GATA2 deficiency

Read it alongside

Total white cell count — the absolute monocyte count is the percentage multiplied by this; a high percentage with a low total count can be normal, and vice versa.
Absolute neutrophil count — a rising monocyte count with recovering neutrophils means marrow recovery; low neutrophils with absent monocytes suggests hairy cell leukemia or marrow failure.
Absolute lymphocyte count — the monocyte-to-lymphocyte ratio rises in tuberculosis and chronic inflammation and is an adverse prognostic marker in several cancers.
Hemoglobin and platelets — anemia or low platelets alongside monocytosis moves the question from 'reactive' to 'marrow' and prompts a smear review.
Peripheral blood smear — distinguishes true monocytes from reactive lymphocytes, immature granulocytes and blasts, and shows dysplastic features suggestive of CMML.
CRP and ESR — raised with infection and inflammation; a persistently high monocyte count with normal inflammatory markers is less likely to be reactive.
Immature granulocytes and blasts — their presence with monocytosis points toward a myeloid neoplasm.
Flow cytometry — in persistent monocytosis, a classical monocyte fraction above about 94 percent supports CMML over a reactive cause; it also identifies hairy cells when monocytes are absent.

What usually happens next

A first mildly high result (0.8 to 1.0 ×10³/µL) during or shortly after an illness is simply repeated in 4 to 8 weeks when you are well; most have normalized by then.
If the count stays above 1.0 ×10³/µL, expect a review of symptoms, medications, smoking and travel, an examination for an enlarged spleen or lymph nodes, a blood smear, CRP and ESR, liver and kidney function, and targeted infection tests (tuberculosis, HIV, blood cultures if feverish).
Monocytosis above 1.0 persisting beyond 3 months with no reactive explanation, or any monocytosis with anemia, low platelets, immature cells on the smear or an enlarged spleen, is referred to hematology for flow cytometry and usually a bone marrow biopsy with genetic testing.
For a low count, the first steps are to check for steroid use and recent illness and to repeat the test; a persistently absent monocyte count with low neutrophils or an enlarged spleen leads to a smear and flow cytometry for hairy cell leukemia.
Ask what the trend looks like across your previous CBCs; a stable count that has been mildly high for years is reassuring, while a steady climb is not.

Diet, lifestyle and natural levers with evidence

What can move Mono abs once the cause is known. Nothing here replaces finding the cause.

Stop smoking

Moderate evidence

Smokers have total white cell counts around 1.0 ×10³/µL higher than non-smokers, and monocytes share in the rise, running roughly 10 to 25 percent higher in large population surveys. After quitting, white cell and monocyte counts decline over the following one to five years toward non-smoker values, and monocyte activation markers linked to atherosclerosis fall sooner. For someone with a borderline count of 0.8 to 1.0 who smokes, this is the single most useful change.

Weight loss when carrying excess abdominal fat

Moderate evidence

Fat tissue in obesity recruits monocytes and keeps them in an inflammatory state. In a study of people undergoing bariatric surgery, total monocytes and the inflammatory CD16-positive subsets fell significantly within three to six months of a 10 to 15 percent weight loss, in step with falling CRP and improving insulin sensitivity. Diet-induced weight loss of around 5 to 10 percent produces smaller but measurable reductions in monocyte counts and activation.

Regular moderate exercise

Preliminary evidence

A 12-week program of combined aerobic and resistance exercise in previously inactive older adults reduced the proportion of inflammatory CD14+CD16+ monocytes and their TNF-alpha production to the levels seen in physically active peers, without changing the total white count. Cross-sectional studies consistently find lower inflammatory monocyte fractions in active people. The total monocyte count changes little, so expect this lever to act on inflammation rather than on the number itself.

A single hard session raises monocytes for a few hours through adrenaline, so avoid testing straight after strenuous exercise.

Mediterranean-style diet high in fiber

Preliminary evidence

Diets rich in vegetables, legumes, whole grains, olive oil and fish lower CRP by about 1 mg/L in trial meta-analyses and reduce monocyte adhesion molecule expression and inflammatory subset activation in small randomized studies. Direct evidence that diet lowers the absolute monocyte count is limited; the clearer benefit is on the chronic low-grade inflammation that keeps the count at the upper end of normal.

Time the test: recover fully before repeating

Strong evidence

Monocytes peak during the recovery week after an infection and rebound after a course of steroids is stopped, so a repeat taken too soon can falsely confirm a 'persistent' monocytosis. Wait at least 4 weeks after any acute illness, and if you have been on prednisone, note the dates for your clinician. No supplement or herb has been shown to lower a monocyte count; the count falls when its cause is treated.

When to see a clinician promptly

An absolute monocyte count above 1.0 ×10³/µL with fever lasting more than a week, drenching night sweats, unexplained weight loss or a new heart murmur: possible tuberculosis, endocarditis or lymphoma, needs prompt assessment.
Monocytosis with anemia, low platelets, a very high or very low white count, or immature cells reported on the smear.
A monocyte count above 1.0 ×10³/µL that has persisted for 3 months or more with no infection or inflammatory cause identified, especially after age 60.
Monocytosis with a feeling of fullness or pain under the left ribs (enlarged spleen), easy bruising or bleeding gums.
A near-absent monocyte count with low neutrophils, recurrent infections or an enlarged spleen, when not on steroids and not acutely ill.
Any white cell abnormality with a high fever (38.3 °C / 101 °F or above), confusion, breathlessness or a fast heart rate, which may be sepsis and needs same-day care.

Frequently asked questions

What is a normal absolute monocyte count?

About 0.2 to 0.8 ×10³/µL (200 to 800 cells per microliter) for adults, which is 2 to 10 percent of white cells. Some labs use 0.1 to 1.0 or 0.3 to 0.9. Children, and especially newborns, run higher. Compare with the range printed on your own report because laboratories differ.

What does mono abs high mean?

It means your absolute monocyte count is above your lab's upper limit, usually 0.8 or 1.0 ×10³/µL. The common reasons are a recent or ongoing infection (monocytes rise during recovery), an inflammatory or autoimmune condition, smoking or excess weight. Most mild rises normalize on a repeat test a month or two later. A count that stays above 1.0 for months without an explanation, especially with other abnormal counts, is evaluated for a bone marrow disorder.

Is a monocyte count of 0.9 or 1.0 high?

Slightly. A value of 0.9 ×10³/µL is just above the usual upper limit of 0.8 and 1.0 is the point at which most clinicians call it monocytosis. During or after an illness this level is expected and needs only a repeat test when you are well. If it persists above 1.0 for more than three months with normal inflammatory markers and no obvious cause, further tests are reasonable.

What does monocytes absolute low mean?

A count below about 0.2 ×10³/µL. The usual reasons are an acute infection (monocytes move into tissue early in a serious infection), corticosteroid medication, or recent chemotherapy, and the count recovers on its own. A persistently absent monocyte count in someone not on steroids, particularly with low neutrophils or an enlarged spleen, is a clue to hairy cell leukemia or marrow failure and should be looked into.

Can high monocytes mean leukemia?

Rarely, yes. Chronic myelomonocytic leukemia is defined by a persistent monocyte count above 0.5 ×10³/µL making up more than 10 percent of white cells for over 3 months, with reactive causes excluded and marrow or genetic confirmation; it mostly affects people over 60 and usually comes with anemia, low platelets or an enlarged spleen. Acute leukemias with monocytic features and some lymphomas also raise monocytes. The overwhelming majority of high monocyte counts, however, are from infection, inflammation, smoking or obesity.

Can stress or anxiety raise monocytes?

Acute stress and hard exercise release adrenaline, which mobilizes monocytes from the spleen and blood vessel walls for a few hours, so a sample taken straight after a stressful event or a workout may read slightly high. Chronic psychological stress, poor sleep and depression are associated with modestly higher monocyte counts and inflammatory monocyte activity in population studies, but they do not produce counts well above 1.0 ×10³/µL; those need another explanation.

What is the monocyte-to-lymphocyte ratio?

It is the absolute monocyte count divided by the absolute lymphocyte count; a typical value is around 0.2 to 0.3. Higher ratios are seen in tuberculosis, chronic inflammation and cardiovascular disease, and a high ratio is an adverse prognostic marker in several cancers and in COVID-19. It is a research and prognostic tool rather than a diagnostic test, and it is not routinely reported.

Do I need to fast for a monocyte count?

No. Monocytes are measured as part of the CBC with differential and are not affected by food. They are affected by recent illness, corticosteroids, smoking, pregnancy and hard exercise within the previous few hours, so mention these to your clinician and, for a repeat test, try to be at least 4 weeks past any acute infection.

References

Blood differential test. MedlinePlus, US National Library of Medicine (2023)View source
Monocytosis. Merck Manual Professional Version (2024)
Monocytopenia. Merck Manual Professional Version (2024)
Riley LK, Rupert J. Evaluation of patients with leukocytosis. American Family Physician (2015)
Lynch DT, Hall J, Foucar K. How I investigate monocytosis. International Journal of Laboratory Hematology (2018)
Patnaik MM, Tefferi A. Chronic myelomonocytic leukemia: 2022 update on diagnosis, risk stratification, and management. American Journal of Hematology (2022)
Khoury JD, Solary E, Abla O, et al.. The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and Histiocytic/Dendritic Neoplasms. Leukemia (2022)
Grever MR, Abdel-Wahab O, Andritsos LA, et al.. Consensus guidelines for the diagnosis and management of patients with classic hairy cell leukemia. Blood (2017)
Dale DC, Boxer L, Liles WC. The phagocytes: neutrophils and monocytes. Blood (2008)
Schwartz J, Weiss ST. Cigarette smoking and peripheral blood leukocyte differentials. Annals of Epidemiology (1994)
Poitou C, Dalmas E, Renovato M, et al.. CD14dimCD16+ and CD14+CD16+ monocytes in obesity and during weight loss: relationships with fat mass and subclinical atherosclerosis. Arteriosclerosis, Thrombosis, and Vascular Biology (2011)
Timmerman KL, Flynn MG, Coen PM, Markofski MM, Pence BD. Exercise training-induced lowering of inflammatory (CD14+CD16+) monocytes: a role in the anti-inflammatory influence of exercise?. Journal of Leukocyte Biology (2008)

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.