Medical expert of the article
New publications
The causes of increase and decrease in monocytes
Last reviewed: 22.11.2021
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
Monocytosis - an increase in the number of monocytes in the blood more than 0.8 × 10 9 / l - accompanies a number of diseases. Monocytes are elevated in tuberculosis; the appearance of monocytosis is considered a proof of the active spread of the tuberculosis process. An important indicator is the ratio of the absolute number of monocytes to lymphocytes, which is normally 0.3-1.0. This ratio is more than 1 in the active phase of the disease and decreases with recovery, which is used to assess the course of tuberculosis.
Diseases and conditions in which monocytosis is possible
Main reasons | Clinical forms |
Infections |
Subacute infective endocarditis; period of recovery after acute infections; viral ( infectious mononucleosis ), fungal, rickettsial and protozoal infections ( malaria, leishmaniasis ) |
Granulomatosis |
Tuberculosis, especially active; syphilis; brucellosis; sarcoidosis; ulcerative colitis |
Diseases of the blood | Acute monoblastic and myelomonoblastic leukemia; chronic monocytic, myelomonocytic and myeloid leukemia; lymphogranulomatosis |
Collagenoses |
Systemic lupus erythematosus, rheumatoid arthritis, nodular polyarteritis |
Also, monocytes are elevated in infectious endocarditis, sluggish sepsis, which is often observed in the absence of leukocytosis. Relative or absolute monocytosis is noted in 50% of patients with systemic vasculitis. Short-term monocytosis can develop in patients with acute infections during convalescence.
Monocytopenia - a decrease in the number of monocytes less than 0.09 × 10 9 / l. Monocytes are lowered by hypoplasia of hematopoiesis.