Diagnosis is by complete blood count (CBC). However, in some cases, a more accurate absolute eosinophil count may be needed. Medical history is taken, with emphasis on travel, allergies and drug use. Specific test for causative conditions are performed, often including chest x-ray, urinalysis, liver and kidney function tests, and serologic tests for parasitic and connective tissue diseases. The stool is often examined for traces of parasites (i.e. eggs, larvae, etc.) though a negative test does not rule out parasitic infection; for example, trichinosis requires a muscle biopsy. Elevated serum B12 or low white blood cell alkaline phosphatase, or leukocytic abnormalities in a peripheral smear indicates a disorder of myeloproliferation. In cases of idiopathic<unk> , the patient is followed for complications. A brief trial of corticosteroids can be diagnostic for allergic causes, as the<unk>  should resolve with suppression of the immune over-response. Neoplastic disorders are diagnosed through the usual methods, such as bone marrow aspiration and biopsy for the leukemias, MRI/CT to look for solid tumors, and tests for serum LDH and other tumor markers.
Eosinophilia
Basophilia
Eosinophiluria
Basopenia
Reticulocytosis
Lycopenemia
Leukopenia
Sarcosinemia