When should monocyte (white blood cell) counts be re-checked?

From the Guidelines

Monocytes should be rechecked every 2-4 weeks in patients with abnormal counts, but in the context of chronic myeloid leukaemia, monitoring every 2 weeks or monthly until month 3 is advised, as per the European LeukemiaNet recommendations 1. When considering the re-checking of monocytes, it's crucial to take into account the clinical context and the specific guidelines for the condition being managed.

• In chronic phase chronic myeloid leukaemia, during the first 4–6 weeks, blood counts, including monocytes, should be monitored weekly 1.
• Later and in the absence of stability of blood counts, monitoring every 2 weeks or monthly until month 3, depending on the stability of blood counts, is advised 1.
• After month 3, monitoring every 3 months is advised, but more frequent monitoring is recommended for patients with advanced disease 1. The decision on when to re-check monocytes should prioritize the patient's overall clinical condition, the severity of any abnormalities in monocyte counts, and the specific treatment or management plan in place.
• For example, in cases where monocytes are being monitored due to concerns about infection or inflammatory conditions, retesting may be warranted after the resolution of these conditions.
• Similarly, for patients on medications that can affect monocyte counts, monitoring should be tailored to the individual's response to treatment and the known effects of the medication on the immune system. Ultimately, the timing of rechecking monocytes is guided by the need to balance the monitoring of potential adverse events with the optimization of treatment outcomes, particularly in the context of conditions like chronic myeloid leukaemia, where dose intensity and response to treatment are critical factors 1.

From the Research

Re-Checking Monocytes

• Monocytosis is a common finding that can be caused by a wide variety of neoplastic and non-neoplastic conditions 2.
• The adequate evaluation of monocytosis involves the integration of laboratory data, morphology, clinical findings, and the judicious use of ancillary studies 2.
• A stepwise diagnostic approach for a patient presenting with monocytosis is recommended, including basic studies and flow cytometry to distinguish between different etiologies 3.
• Monocytosis is associated with an increased risk of all types of haematological malignancy, with the greatest relative risk increase observed in chronic myelomonocytic leukaemia (CMML) 4.
• Sustained monocytosis (at least two requisitions in 3 months) further increases CMML risk, and haematological malignancy should mainly be suspected when monocytosis is sustained or the clinical presentation raises suspicion of malignancy 4.
• A laboratory-based approach to neoplastic monocytosis is recommended, including in-depth elucidation of the genomic landscape of myeloid neoplasms 5.
• Genetic findings can shed light on potential disease response to various therapeutic agents used in the setting of myeloid neoplasms 5.

Timing of Re-Check

• Re-check monocytes when there is sustained monocytosis (at least two requisitions in 3 months) 4.
• Re-check monocytes when the clinical presentation raises suspicion of malignancy 4.
• Re-check monocytes as part of a stepwise diagnostic approach for a patient presenting with monocytosis 3.