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

From the Guidelines

Elevated monocyte count, also known as monocytosis, is a condition that requires prompt medical evaluation to determine the underlying cause, as it can be associated with various conditions, including infections, inflammatory diseases, and certain types of cancer. The total white blood cell count and differential may provide a suggestion of a bacterial etiology when viral or parasitic etiologies are also being considered, and monocyte predominance may suggest the presence of an intracellular pathogen such as Salmonella 1. Some of the key points to consider when evaluating a patient with elevated monocytes include:

• The patient's medical history and symptoms, such as fever, weight loss, and fatigue
• The results of additional tests, including a complete blood count with differential, inflammatory markers, and possibly imaging or bone marrow examination
• The potential for underlying conditions, such as chronic infections, inflammatory diseases, and certain types of cancer, including leukemia and lymphoma 1
• The importance of maintaining good general health through adequate rest, hydration, and nutrition while waiting for medical evaluation It is essential to note that monocytes are an important type of white blood cell that help fight infections and remove damaged tissues, so their elevation typically represents the body's immune response to some challenge. In some cases, persistent monocytosis without an identified cause may require follow-up monitoring, as it occasionally may be an early sign of myeloid disorders, such as chronic myeloid leukemia (CML), which can progress from a chronic phase to an accelerated phase and eventually to a blast phase 1. Therefore, it is crucial to consult with a healthcare provider for proper evaluation and treatment of the underlying cause of elevated monocytes, rather than focusing solely on the elevated monocyte count itself.

From the Research

Implications of Elevated Monocyte Count

• Elevated monocyte count has been associated with various inflammatory disorders and alterations to these cells can have pathological significance 2
• Studies have shown that monocyte subsets, including classical, intermediate, and non-classical monocytes, play a crucial role in the disruption of the homeostasis of the normal bone marrow microenvironment 3
• Elevated monocyte count has been linked to poor outcomes in intracerebral hemorrhage, with higher monocyte counts being independently associated with 30-day case fatality 4
• In multiple myeloma, peripheral blood monocyte count is a dynamic prognostic biomarker, with abnormal monocyte counts at diagnosis being associated with inferior overall survival 5
• Elevated mature monocytes in bone marrow have been shown to predict a poor prognosis in myelodysplastic syndromes, with a higher IPSS-R score and inferior overall survival 6

Association with Diseases

• Monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma have been associated with alterations in monocyte subsets, including decreased classical monocytes and increased intermediate and non-classical monocytes 3
• Intracerebral hemorrhage has been linked to elevated monocyte counts, with higher counts being associated with poor outcomes 4
• Multiple myeloma has been associated with abnormal monocyte counts, with peripheral blood monocyte count being a dynamic prognostic biomarker 5
• Myelodysplastic syndromes have been associated with elevated mature monocytes in bone marrow, with a higher IPSS-R score and inferior overall survival 6

Prognostic Value

• Elevated monocyte count has been shown to be a prognostic biomarker in multiple myeloma, with abnormal monocyte counts at diagnosis being associated with inferior overall survival 5
• Elevated mature monocytes in bone marrow have been shown to be an independent adverse prognostic factor for overall survival in myelodysplastic syndromes 6
• Monocyte subsets, including classical, intermediate, and non-classical monocytes, may provide a novel evaluation factor for MDS patients, especially when their karyotype analyses fail 6