What laboratory tests are used for the diagnosis and management of lymphoma?

Laboratory Tests for Lymphoma Diagnosis and Management

Complete blood count, lactate dehydrogenase (LDH), uric acid, beta-2-microglobulin, protein electrophoresis, and screening for HIV, hepatitis B and C are the essential laboratory tests required for lymphoma evaluation. 1

Initial Diagnostic Laboratory Panel

Mandatory Blood Tests

• Complete blood count (CBC) with differential to assess for cytopenias, leukocytosis, or abnormal cells 1
• Lactate dehydrogenase (LDH) - critical prognostic marker that reflects tumor burden and cell turnover 1
• Uric acid - important for assessing tumor lysis syndrome risk, particularly in high tumor burden cases 1
• Routine blood chemistry including electrolytes, renal function (BUN, creatinine), and liver function tests 1

Strongly Recommended Tests

• Beta-2-microglobulin (B2M) - independent prognostic factor that correlates with tumor burden and survival 2, 3
• Protein electrophoresis - recommended for B-cell lymphomas to detect monoclonal proteins 1

Infectious Disease Screening

• HIV serology - mandatory screening as HIV affects prognosis and treatment selection 1
• Hepatitis B and C screening - required before initiating immunochemotherapy, particularly rituximab-containing regimens 1

Prognostic Significance of Key Laboratory Markers

LDH as a Prognostic Tool

Elevated LDH is the single most important serologic prognostic marker in lymphoma, incorporated into the International Prognostic Index (IPI) scoring system. 1 LDH levels correlate directly with disease burden, treatment response, and overall survival. 2 Patients with markedly elevated LDH (>2 times normal) have significantly worse outcomes and require more aggressive treatment approaches. 1

Beta-2-Microglobulin

B2M combined with LDH provides superior risk stratification compared to either marker alone. 2, 3 The combination of these two markers can define three distinct prognostic groups with dramatically different outcomes - from 100% survival in low-risk patients to only 26% survival in high-risk patients. 2

Additional Tissue-Based Testing

Bone Marrow Evaluation

• Bone marrow aspirate and biopsy - required for all patients amenable to curative therapy to complete staging 1
• Should be repeated at end of treatment only if initially involved 1

Immunohistochemistry Requirements

Minimal mandatory antibody panel includes CD45, CD20, and CD3 on tissue specimens. 1 Optional markers include CD10, BCL-2, and MUM1 for germinal center versus activated B-cell subtype differentiation, though this does not currently influence treatment decisions. 1

Special Circumstances

High-Risk Features Requiring Additional Testing

• Lumbar puncture with CSF analysis should be considered in high-risk patients (IPI ≥2, bone marrow involvement, testicular involvement, or involvement of spine/skull base) 1
• First diagnostic spinal tap should be combined with prophylactic intrathecal chemotherapy (cytarabine and/or methotrexate) 1

Cardiac Assessment

• Left ventricular ejection fraction (LVEF) assessment required before anthracycline-based chemotherapy 1
• Performance status evaluation mandatory before treatment initiation 1

Monitoring During Treatment

Serial LDH measurements are useful for monitoring disease activity and treatment response, as declining levels correlate with therapeutic efficacy. 4 Repeat imaging and laboratory studies should occur after 2-4 cycles of chemotherapy and after completion of treatment. 1

Common Pitfalls to Avoid

• Do not rely on core needle biopsies alone - excisional lymph node biopsy providing adequate tissue is strongly preferred for accurate diagnosis and immunohistochemistry 1
• Do not delay infectious disease screening - hepatitis B reactivation can be fatal during rituximab therapy if not identified and managed prophylactically 1
• Do not ignore mildly elevated LDH - even high-normal LDH levels (compared to low-normal) predict shorter survival regardless of tumor mass 5