Low monocyte count, known as monocytopenia, can be caused by various factors. It can result from certain viral infections, autoimmune diseases, bone marrow disorders, chemotherapy or radiation treatment, certain medications, or inherited immune deficiencies. Additionally, nutritional deficiencies, such as vitamin B12 or folate deficiency, can affect monocyte production. Identifying the underlying cause of monocytopenia is crucial, and a healthcare professional can perform further investigations to determine the specific reason and recommend appropriate treatment, if necessary.