Appropriate Blood Work for a General Medical Evaluation
For a general medical evaluation, the recommended blood work should include complete blood count, urinalysis, serum electrolytes (including calcium and magnesium), blood urea nitrogen, serum creatinine, fasting blood glucose (glycohemoglobin), lipid profile, liver function tests, and thyroid-stimulating hormone. 1
Core Laboratory Tests
Basic Panel
- Complete blood count (CBC) with differential - provides critical information about cell components in blood that can predict risk of cardiovascular disease, metabolic disorders, and other conditions 2
- Comprehensive metabolic panel including:
- Serum electrolytes (including calcium and magnesium)
- Blood urea nitrogen
- Serum creatinine
- Liver function tests 1
- Fasting blood glucose or glycohemoglobin (HbA1c) - essential for diabetes screening and management 1
- Lipid profile (total cholesterol, LDL, HDL, triglycerides) - critical for cardiovascular risk assessment 1
- Thyroid-stimulating hormone (TSH) - important for thyroid function evaluation 1
- Urinalysis - provides information on kidney function and potential urinary tract issues 1
Additional Tests Based on Age and Risk Factors
- For patients with diabetes: vitamin B12 levels if on metformin 1
- For patients on ACE inhibitors, ARBs, or diuretics: serum potassium levels 1
- For patients at risk of nutritional deficiencies: calcium, vitamin D, and phosphorous levels 1
Value of Complete Blood Count (CBC)
The CBC provides unique information beyond traditional risk factors and is strongly associated with all-cause mortality 3. Key components include:
- White blood cell count and differential - associated with inflammation and cardiovascular risk 3
- Hemoglobin and hematocrit - identify anemia and polycythemia 1
- Red cell indices (MCV, MCH, RDW) - help classify types of anemia 1
- Platelet count - screens for bleeding or clotting disorders 2
Interpreting Results
- CBC results should be evaluated in context of the patient's stable baseline or "setpoint" rather than just population reference ranges 4
- Abnormal CBC results should be approached systematically to determine the underlying cause 5
- For anemia workup, consider red blood cell indices, reticulocyte count, and iron studies 1
Common Pitfalls to Avoid
- Relying solely on population reference ranges without considering patient-specific baselines can lead to missed diagnoses 4
- Failing to repeat abnormal values before extensive workup may lead to unnecessary testing 5
- Not considering medications that may affect laboratory values (e.g., metformin affecting vitamin B12 levels) 1
- Overlooking the need for fasting before certain tests (lipids, glucose) which can affect interpretation 1
Special Considerations
- In elderly patients (≥65 years), consider additional assessment for cognitive and functional performance 1
- For patients with risk factors for heart disease, electrocardiogram and cardiac biomarkers may be appropriate 1
- For patients with specific symptoms or risk factors, targeted additional testing should be considered rather than excessive screening 1
The CBC and basic metabolic panel provide essential information for disease screening and risk assessment, with evidence showing they can predict cardiovascular events, metabolic disorders, and mortality risk 2, 3. These tests should form the foundation of any general medical evaluation.