What labs should I check?

Laboratory Testing Recommendations

Essential Initial Laboratory Panel

For any patient requiring laboratory evaluation, obtain a comprehensive basic metabolic panel (BMP) including electrolytes (sodium, potassium, chloride, bicarbonate), renal function tests (BUN, creatinine, eGFR), glucose, and calcium, along with a complete blood count (CBC) with differential and liver function tests (ALT, AST, alkaline phosphatase, albumin). 1

Core Laboratory Tests

• Complete Blood Count (CBC) with differential: Essential for detecting anemia, thrombocytopenia, leukocytosis, or other hematologic abnormalities 1

• Comprehensive Metabolic Panel:

  • Electrolytes (sodium, potassium, chloride, bicarbonate) 1
  • Renal function (creatinine, BUN, eGFR) 1
  • Glucose or hemoglobin A1c 1
  • Calcium 1
  • Albumin 1

• Liver Function Tests: ALT, AST, alkaline phosphatase, total bilirubin 1

• Coagulation Studies: PT/INR and aPTT if bleeding concerns, anticoagulation use, or pre-procedural evaluation 1, 2

• Lactate Dehydrogenase (LDH): Important prognostic marker for hemolysis, lymphoma, and tissue damage 1, 2

Additional Testing Based on Clinical Context

Inflammatory and Infection Markers

• C-reactive protein (CRP): Monitor disease activity, particularly in inflammatory conditions 1
• Erythrocyte sedimentation rate (ESR): Consider for inflammatory or rheumatologic conditions 1
• Troponin: If cardiac injury suspected 1

Hematologic Evaluation

• Serum tryptase and vitamin B12: Essential if myeloproliferative disorder suspected, particularly with unexplained splenomegaly or eosinophilia 1, 2
• Serum protein electrophoresis (SPEP): Evaluate for paraproteinemia if multiple myeloma or plasma cell disorder suspected 1, 2
• Serum free light chain assay: Important for monitoring plasma cell disorders 1
• β2-microglobulin: Prognostic marker for hematologic malignancies 1, 2

Metabolic and Endocrine Testing

• Thyroid function tests (TSH, free T4): Include when thyroid dysfunction suspected or in patients with metabolic disturbances 2, 3
• Lipid profile: Fasting or non-fasting for cardiovascular risk assessment 1
• Hemoglobin A1c: Screen for diabetes or monitor glycemic control 1

Bone Metabolism (if fractures or bone disease suspected)

• Serum calcium, phosphorus, alkaline phosphatase: Systematically or based on clinical context 1
• 25-hydroxy-vitamin D and parathyroid hormone: When bone metabolism disorders suspected 1
• Serum copper and ceruloplasmin: If metabolic bone disease considered 1

Specialized Testing for Specific Scenarios

Bleeding or Coagulopathy Concerns

• Extended coagulation panel: Factor VIII, IX, XI, XIII levels and von Willebrand activity if unexplained bleeding 2
• Platelet count and function: Part of CBC but critical for bleeding evaluation 1, 2

Suspected Hematologic Malignancy

• Flow cytometry: Peripheral blood immunophenotyping if lymphoproliferative disorder suspected 1, 2
• JAK2, CALR, MPL mutations: If myeloproliferative neoplasm suspected 2
• Quantitative immunoglobulins (IgG, IgA, IgM, IgE): Evaluate for immunodeficiency or paraprotein 1

Abdominal or Thoracic Injury (if trauma suspected)

• Liver enzymes (ALT, AST): Systematically for thoracoabdominal injuries 1
• Pancreatic enzymes (lipase, amylase): If abdominal trauma or pancreatitis suspected 1
• Urinalysis: Detect hematuria suggesting renal injury 1
• Creatine kinase and troponin: If cardiac or muscle injury suspected 1

Urine Studies

• 24-hour urine collection: Total protein, urine protein electrophoresis (UPEP), and immunofixation (UIFE) when plasma cell disorder or significant proteinuria suspected 1
• Urinalysis with microscopy: Routine evaluation for renal disease, infection, or hematuria 1

Critical Pitfalls to Avoid

• Do not order routine daily laboratory tests without clinical indication: Studies show that routine postoperative BMP testing in patients with normal preoperative values and no major comorbidities rarely yields actionable information 4

• Recognize non-normal distributions: Plasma potassium and bicarbonate are significantly right-skewed and may be bimodal; use nonparametric statistical methods when analyzing these values 5

• Target testing to specific risks: Patients with diabetes require glucose monitoring, those with chronic kidney disease need renal function and potassium monitoring, and those with abnormal preoperative values warrant repeat testing 4

• Consider timing of tests: Baseline testing before medication initiation is essential, with frequency adjusted based on medication toxicity profiles (e.g., methotrexate requires CBC and liver/renal function every 3-4 months) 1

• Do not delay treatment while awaiting results: In acute scenarios like severe colitis, initiate steroids without waiting for stool culture results 1