Full blood count – in early stages of the disease, there is a mature lymphocytosis with smear cells without perturbation of other cell lineages. Cytopenias may develop in later stages with progressive bone marrow infiltration.
Blood film may occasionally show cytopenias due to immune destruction (eg, haemolysis, immune thrombocytopenia), or if splenomegaly is present (from splenic sequestration).
Flow cytometry on lymphocytes shows a typical immunophenotype (CD5/19 coexpressing cells with CD23 positivity and weak light chain restriction).
Bone marrow aspiration and trephine biopsy are not always required if a definite diagnosis is available on immunophenotyping. However, may be indicated when therapy for CLL is to be commenced to assess tumour burden and for prognostic cytogenetic studies.
Immunoglobulins levels of IgG, A, M; Protein electrophoresis - serum with immunofixation to detect a paraprotein.
See Table 2.
Immunoglobin heavy chain mutation status or Zap-70 assessment have been shown to correlate with clinical outcome, however, tests such as ZAP-70 are not readily available at all laboratories, and are not standardised across laboratories..
Beta-2-microglobulin and Lactate dehydrogenase in serum.
Lymph node biopsy is rarely indicated.
See Table 1.