What lab work should be done for a comprehensive workup?

Comprehensive Laboratory Workup for Clinical Evaluation

A comprehensive laboratory workup should include complete blood count with differential, comprehensive metabolic panel, serum lactate dehydrogenase, serum tryptase, vitamin B12 levels, and peripheral blood smear review as the core initial tests. 1

Initial Core Laboratory Tests

The following laboratory tests should be performed for a thorough initial evaluation:

• Complete Blood Count (CBC) with differential

  • Essential for detecting abnormalities in blood cell counts including eosinophilia, dysplasia, monocytosis, and circulating blasts 1
  • Provides critical baseline hematologic parameters

• Comprehensive Metabolic Panel (CMP)

  • Including liver function tests, uric acid, and renal function tests 1
  • Evaluates organ function and metabolic status

• Lactate Dehydrogenase (LDH)

  • Important prognostic marker in many hematologic conditions 1

• Serum Tryptase and Vitamin B12 levels

  • Particularly important when evaluating for myeloproliferative disorders 1
  • Elevated levels commonly observed in myeloid neoplasms with PDGFRA fusion gene

• Peripheral Blood Smear Review

  • Critical for morphologic assessment of blood cells 1
  • Evaluates for dysplasia, abnormal cells, and blasts

Disease-Specific Additional Testing

For Suspected Hematologic Malignancies

• Bone Marrow Aspirate and Biopsy with:

  • Immunohistochemistry (IHC) for CD117, CD25, tryptase, and reticulin/collagen stains 1
  • Conventional cytogenetics 1
  • Fluorescence in situ hybridization (FISH) 1
  • Reverse transcription PCR (RT-PCR) for fusion gene detection 1
  • Flow cytometry for immunophenotyping 1

• Hepatitis B and C Testing

  • Essential before initiating immunotherapy or chemotherapy 1
  • HBsAg and HBcAb testing required before anti-CD20 monoclonal antibody therapy

• Immunophenotypic Analysis

  • For lymphoid neoplasms: CD19, CD20, CD5, CD10, CD11c, CD22, CD25, CD103, CD123, cyclin D1, and CD200 1
  • For myeloid disorders: appropriate myeloid markers 1

For Suspected Cardiovascular Disorders

• Cardiac Biomarkers

  • Cardiac troponins 1
  • BNP or NT-proBNP for suspected heart failure 1

• Thyroid Function Tests

  • TSH to rule out thyroid dysfunction 1

Special Considerations

For Pediatric Patients

• Genetic Testing
  • Chromosomal microarray (CMA) and fragile X testing for developmental disorders 1
  • Metabolic testing when clinically indicated 1

For Suspected Eosinophilic Disorders

• Additional Testing Based on Clinical Presentation:
  • Serology for Strongyloides and parasitic infections
  • Antineutrophil cytoplasmic antibodies and antinuclear antibodies
  • Stool ova and parasites test
  • Quantitative serum immunoglobulin levels (including IgE)
  • Erythrocyte sedimentation rate and/or C-reactive protein
  • Aspergillus IgE to evaluate for allergic bronchopulmonary aspergillosis 1

Cost-Effective Approach

When ordering laboratory tests, consider a staged approach to minimize unnecessary testing:

1. Start with core tests (CBC, CMP, LDH)
2. Add specialized tests based on initial results and clinical suspicion
3. Consider cost implications - using BMP instead of CMP when liver function is not a concern can result in significant cost savings 2

Common Pitfalls to Avoid

• Incomplete testing: Failing to order appropriate disease-specific tests can delay diagnosis
• Over-testing: Ordering unnecessary tests increases costs without improving outcomes
• Inadequate follow-up: Abnormal results require appropriate follow-up testing
• Missing hepatitis testing: Critical before initiating immunotherapy in hematologic malignancies 1

By following this structured approach to laboratory workup, clinicians can efficiently diagnose conditions while minimizing unnecessary testing and costs.