My one year old has high monocytes (1.8 absolute) and low neutrophils (0.5 absolute) could this be an indication of leukemia?

Viral more likely: The low neutrophils should be followed. The most common cause for the low neutrophils is some type of infection (usually viral infection). If this is so, i would expect things to get better within a month's time. Leukemia often causes other blood counts to be low (platelets, hemoglobin). But do have the blood counts followed in a few weeks.

Unlikely...: As mentioned, viruses can transiently cause low neutrophils. Another cause could be auto-antibodies directed toward neutrophils (also temporary). An increased monocyte count is usually the body's natural response to low neutrophils to help fight infection. If other counts (red blood cells or platelets) go low or new concerning symptoms (unexplained fevers), may need further evaluation (peds heme).

Probably not: At this age, the most likely cause for neutropenia (low neutrophils) accompanied by mild absolute monocytosis (normal is about 1) is an infection, most commonly viral. Consulting with your pediatrician is recommended.