What are the causes of elevated monocyte (white blood cell) count?

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Last updated: April 23, 2025View editorial policy

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From the Guidelines

Elevated monocytes, or monocytosis, can be caused by various conditions including infections, inflammatory disorders, and certain cancers, and a comprehensive diagnostic workup is necessary to determine the underlying cause, as recommended by the management recommendations for chronic myelomonocytic leukemia: consensus statements from the sie, sies, gitmo groups 1. The diagnostic workup of a suspected CMML should include patient’s history aimed at excluding reactive causes of monocytosis, physical examination, complete blood count and peripheral blood smear examination with differential leukocyte count, bone marrow aspiration and biopsy, conventional cytogenetic analysis, and molecular assays to exclude bcr/abl fusion gene and rearrangement of PDGFRA and PDGFRB 1. Some of the common causes of monocytosis include:

  • Bacterial infections like tuberculosis and endocarditis
  • Viral infections such as mononucleosis and HIV
  • Chronic inflammatory conditions like inflammatory bowel disease, rheumatoid arthritis, and lupus
  • Blood disorders and cancers, particularly chronic myelomonocytic leukemia, Hodgkin lymphoma, and multiple myeloma
  • Certain medications, including corticosteroids
  • Recovery from bone marrow suppression
  • Stress, both physical and psychological It is essential to note that the management recommendations for chronic myelomonocytic leukemia: consensus statements from the sie, sies, gitmo groups 1 and the guidelines on the diagnosis and management of pericardial diseases executive summary; the task force on the diagnosis and management of pericardial diseases of the european society of cardiology 1 provide valuable insights into the diagnosis and management of monocytosis, but the most recent and highest quality study, management recommendations for chronic myelomonocytic leukemia: consensus statements from the sie, sies, gitmo groups 1, should be prioritized when making a definitive recommendation. The comprehensive diagnostic criteria proposed by the FAB group in the 1980s and the WHO classification in 2001, as mentioned in the study 1, can help establish a diagnosis of CMML, but it is crucial to consider the most recent and highest quality evidence when making a recommendation. In summary, a comprehensive diagnostic workup, including patient’s history, physical examination, complete blood count, peripheral blood smear examination, bone marrow aspiration and biopsy, conventional cytogenetic analysis, and molecular assays, is necessary to determine the underlying cause of monocytosis, as recommended by the management recommendations for chronic myelomonocytic leukemia: consensus statements from the sie, sies, gitmo groups 1.

From the Research

Elevated Monocytes Causes

  • Rheumatoid arthritis (RA) is associated with an increased risk of serious infections, which can lead to elevated monocytes 2, 3, 4, 5, 6
  • The disease itself, altered immunological function, disability, immobility, joint surgery, and extra-articular manifestations can contribute to frequent infections in RA patients 3, 6
  • The use of biological drugs, such as tumor necrosis factor-alpha (TNF-α) inhibitors, can increase the risk of serious infections, including tuberculosis 3, 4, 6
  • Glucocorticoids (GCs) can also increase the risk of serious infections in a dose-dependent manner 6
  • Comorbid conditions, such as diabetes, chronic lung or kidney disease, and lifestyle factors like smoking, can further increase the risk of infections in RA patients 6
  • Premature ageing of the immune system in RA may contribute to weakened protection against infectious organisms, leading to elevated monocytes 6

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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