Neutropenic Fever is defined as a single temperature above 38.3°C taken in the mouth or a body temperature greater than 38.0°C sustained for more than one hour in a child with neutropenia1. Neutropenia commonly occurs post chemotherapy because the number of neutrophils (a type of white blood cell) in the bloodstream decreases after a child receives chemotherapy. A child has neutropenia when his or her Absolute Neutrophil Count (ANC) is less than 1500/mm3.
Our white blood cells are the soldiers of our body against invaders such as bacteria, fungi and viruses. Amongst them is an important soldier – neutrophil.
When a child undergoes chemotherapy and radiation therapy, these agents cause the bone marrow function to become poorer. In addition, certain cancers that invade the bone marrow cause a decrease in the number of blood cells.
When the effect of the cancer or the therapeutic agents is severe enough, the number of soldiers in our body including neutrophils is greatly reduced and the child becomes vulnerable to infection. The risk of a serious infection in a child receiving treatment for cancer is related to the degree and duration of neutropenia.
A normal ANC is more than 1500/mm3. Children with brief periods of neutropenia (ANC 200/mm3 to 500/mm3) and fever for less than 7 days respond better than those with severe neutropenia (ANC less than or equal to 200/mm3) lasting more than 7 days. Lung infections, skin infections and blood infections occur more frequently when the ANC falls below 500/mm3. The risk of a life-threatening infection increases further when the ANC is less than 200/mm3.
Neutropenia and its nadir (lowest point that one's blood cell count will reach) often occur between 7 and 14 days after a child receives chemotherapy. This period can be different depending on the underlying condition and chemotherapy received. Depending on the chemotherapy regimen given, the immune system is suppressed to varying degrees. For example, patients with acute myeloid leukaemia may have periods of severe neutropenia for up to 4 weeks as compared to patients with standard risk acute lymphoblastic leukaemia in which the neutrophil counts usually recover by day 10.
Neutropenic Fever is the most common side effect from cancer treatment. Fever in a neutropenic child should be managed as a medical emergency as he or she is at risk of bacterial sepsis (bacterial infection) if left untreated. Children who have any form of immunodeficiency or recently received chemotherapy are at risk of developing Neutropenic Fever and hence a full blood count (FBC) should be performed urgently in these patients at the onset of fever.