Which lab work is crucial in diagnosing febrile neutropenia?

The key laboratory work for diagnosing febrile neutropenia is a complete blood count (CBC). This test assesses various components of the blood, including the number of white blood cells, red blood cells, and platelets. In febrile neutropenia, a patient typically presents with a fever and a significantly reduced number of neutrophils, which are critical components of the immune system that help fight off infections.

A CBC will reveal low levels of neutrophils, confirming neutropenia and indicating the body's decreased ability to respond to infections, which is critical for diagnosing this condition. Other tests listed, such as liver function tests, B-type natriuretic peptide, and thyroid function tests, do not provide information on white blood cell counts or neutrophil levels and are thus not directly relevant to the diagnosis of febrile neutropenia.