Baseline Laboratory Studies for Initial Patient Assessment
For any patient presenting for initial assessment, obtain a comprehensive metabolic panel including complete blood count, urinalysis, serum electrolytes (sodium, potassium, calcium, magnesium), blood urea nitrogen, serum creatinine, fasting glucose, lipid profile, liver function tests, iron studies (serum iron, ferritin, transferrin saturation), and thyroid-stimulating hormone 1.
Essential Laboratory Tests
The following labs form the foundation of initial evaluation across most clinical presentations:
- Complete blood count (CBC) - screens for anemia, infection, hematologic disorders
- Comprehensive metabolic panel - assesses renal function, electrolyte balance, glucose metabolism, liver function
- Urinalysis - detects renal disease, diabetes, infection
- Lipid profile (fasting) - evaluates cardiovascular risk
- Thyroid-stimulating hormone (TSH) - screens for thyroid dysfunction
- Iron studies (serum iron, ferritin, transferrin saturation) - identifies iron deficiency or overload 1
Next Steps After Initial Labs
Obtain a 12-lead ECG
Perform electrocardiography at the initial encounter to assess for arrhythmias, ischemia, conduction abnormalities, and structural heart disease 1. This is essential regardless of presenting complaint.
Context-Specific Additional Testing
The initial labs should trigger additional targeted evaluation based on clinical presentation:
If cardiovascular symptoms present:
- Measure BNP or NT-proBNP if dyspnea or heart failure suspected (BNP >500 pg/mL or NT-proBNP >900 pg/mL indicates high probability of heart failure) 1
- Order troponin if acute coronary syndrome suspected 2
- Obtain chest radiograph (PA and lateral views) 3
If developmental delay or neurodevelopmental concerns:
- Perform chromosomal microarray (CMA) and Fragile X testing as first-tier genetic tests 4
- Consider metabolic testing if clinical indicators suggest inborn errors of metabolism 4
If recurrent infections or immunodeficiency suspected:
- Check HIV serology in appropriate risk populations 5
- Consider immunoglobulin levels and lymphocyte subsets 6
If autoimmune disease suspected (particularly in type 1 diabetes):
- Screen for celiac disease and additional thyroid antibodies 7
Critical Pitfalls to Avoid
- Don't skip iron studies - these are now standard in initial evaluation, particularly given high prevalence of iron deficiency affecting multiple organ systems 1
- Don't order genetic testing without clinical indication - start with family history and physical examination to guide targeted testing rather than broad panels 4
- Don't forget to assess volume status and vital signs including orthostatic blood pressure changes and body mass index calculation 3
Documentation Requirements
Document a three-generation family history when cardiomyopathy, genetic disorders, or neurodevelopmental conditions are suspected, as this guides subsequent genetic testing decisions 4, 1.
The strength of these recommendations comes from consistent guidance across multiple professional societies (AHA/ACC/HFSA, AAP, ACMG) with the most recent 2022 guidelines providing the current standard 1.