Laboratory Workup for a Full Medical Evaluation
A comprehensive laboratory workup should begin with a complete blood count (CBC) with differential, comprehensive metabolic panel (CMP), and additional targeted tests based on clinical context and risk factors.
Core Laboratory Studies
Essential First-Line Tests
Complete Blood Count (CBC) with differential is the foundation of any full workup, providing critical information about red blood cells, white blood cells, and platelets that can identify anemia, infection, hematologic malignancies, and predict cardiovascular disease risk 1, 2, 3.
Comprehensive Metabolic Panel (CMP) should include serum electrolytes, blood urea nitrogen, creatinine (for renal function), glucose, calcium, liver function tests (AST, ALT, alkaline phosphatase, bilirubin), albumin, and total protein 4.
Thyroid function testing (TSH) is recommended as part of routine screening, particularly given its role in multiple disease states including pulmonary hypertension and macrocytosis 4, 5.
Additional Routine Studies
Lipid panel (total cholesterol, LDL, HDL, triglycerides) for cardiovascular risk assessment 4.
Hemoglobin A1c (HbA1c) for diabetes screening and glycemic control assessment 4.
Urinalysis to complete the minimum database and screen for renal disease, infection, and metabolic abnormalities 4.
Coagulation profile (PT/INR, PTT) when bleeding risk, liver disease, or anticoagulation is a consideration 4.
Context-Specific Laboratory Additions
When Anemia is Present or Suspected
Iron studies including serum ferritin, transferrin saturation, and total iron-binding capacity to differentiate iron deficiency from anemia of chronic disease 1, 2.
Reticulocyte count to distinguish between decreased red blood cell production versus increased destruction or loss 1, 2.
Vitamin B12 and folate levels when macrocytosis (MCV >100 fL) is present 1, 5.
Methylmalonic acid (MMA) and homocysteine if B12 deficiency is suspected but serum levels are equivocal 5.
C-reactive protein (CRP) to assess for inflammation that may alter interpretation of iron studies 1.
When Liver Disease is Suspected
Hepatitis serologies (HBsAg, hepatitis B surface antibody, hepatitis B core antibody, HCV antibodies) with viral load confirmation if positive 4.
Extended liver function panel including direct and indirect bilirubin, GGT, and prothrombin time 4.
When Malignancy is Suspected
Lactate dehydrogenase (LDH) as a marker of cell turnover and tissue damage 4.
Tumor markers when specific malignancies are suspected (e.g., AFP for hepatocellular carcinoma, though not for routine screening) 4.
Serum protein electrophoresis if multiple myeloma or other plasma cell disorders are considered 4.
When Autoimmune Disease is Suspected
Antinuclear antibody (ANA) as an initial screening test 4.
If ANA is positive, proceed with specific autoimmune antibody panel including anti-dsDNA, anti-Scl-70, anti-centromere, anti-RNP, anti-SSA, anti-SSB 4.
When Cardiovascular or Pulmonary Disease is Suspected
N-terminal pro B-type natriuretic peptide (NT-proBNP) for heart failure assessment and pulmonary hypertension workup 4.
High-sensitivity troponin if acute coronary syndrome is a consideration 4.
When Infectious Disease Risk is Present
HIV testing particularly in patients with risk factors or unexplained symptoms 4.
Hepatitis B and C serologies as noted above 4.
When Hematologic Abnormalities are Present
Peripheral blood smear examination to evaluate cell morphology, particularly when CBC shows unexplained abnormalities 1, 5.
Hypercoagulable panel when indicated by clinical history of thromboembolism 4.
Critical Interpretation Principles
Common Pitfalls to Avoid
Do not rely on single parameters in isolation: The CBC provides unique information beyond traditional risk factors, with components like white blood cell count, neutrophil count, and hemoglobin strongly associated with cardiovascular disease and mortality 3.
Consider inflammatory status when interpreting iron studies: Ferritin <30 μg/L indicates iron deficiency in non-inflammatory states, but 30-100 μg/L with inflammation may still indicate iron deficiency; always measure CRP concurrently 1.
Recognize that "normal" reticulocyte counts may be inappropriately low in anemic patients: The bone marrow should respond to anemia with increased production; a normal count suggests inadequate response 2.
Do not miss coexisting deficiencies: Normal MCV with high RDW may indicate mixed deficiency anemia where different deficiencies counterbalance each other 1.
Integration with Clinical Context
Timing matters: Complete all requisite laboratory studies before proceeding to invasive procedures like right heart catheterization or bone marrow biopsy to ensure complete disease characterization 4.
Renal function assessment is critical: Creatinine is both a prognostic marker in liver disease and essential for determining drug dosing, particularly for renally excreted medications 4.
Pregnancy status must be determined in patients of childbearing potential before initiating any treatment 4.
Special Populations
Preoperative Assessment
- Minimum blood workup before surgery includes CBC, CMP, liver function tests, alkaline phosphatase, calcium, and coagulation studies 4.