What initial laboratory tests should be ordered for a new patient at a family medicine clinic?

Initial Laboratory Tests for New Family Medicine Patients

For new patients at a family medicine clinic, the recommended initial laboratory tests 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 Initial Laboratory Panel

The following laboratory tests should be ordered for all new adult patients:

1. Complete Blood Count (CBC) with platelets

   • Screens for anemia, infections, and hematologic disorders
   • Includes white blood cell count, hemoglobin, hematocrit, and platelet count

2. Comprehensive Metabolic Panel (CMP)

   • Serum electrolytes (sodium, potassium, chloride, bicarbonate)
   • Calcium and magnesium
   • Blood urea nitrogen (BUN) and creatinine
   • Estimated glomerular filtration rate (eGFR)
   • Fasting blood glucose
   • Liver function tests (ALT, AST, alkaline phosphatase, total bilirubin)
   • Total protein and albumin

3. Lipid Profile

   • Total cholesterol
   • LDL cholesterol
   • HDL cholesterol
   • Triglycerides

4. Thyroid-Stimulating Hormone (TSH)

   • Screens for thyroid dysfunction

5. Urinalysis

   • Screens for urinary tract infections, kidney disease, and diabetes

Additional Considerations Based on Patient Factors

Age-Specific Testing

• Adults ≥65 years:
  • Consider assessment for cognitive performance
  • Consider assessment for functional performance 1

Medication-Specific Testing

• For patients on or starting specific medications:
  • Vitamin B12 if on metformin
  • Serum potassium for patients on ACE inhibitors, ARBs, or diuretics 1

Disease-Specific Testing

• For patients with diabetes:
  • Hemoglobin A1C (if not done in past 3 months)
  • Spot urinary albumin-to-creatinine ratio 1

Practical Implementation Tips

• Order these tests prior to the patient's first visit when possible to have results available for discussion during the initial encounter
• Consider point-of-care testing for certain analytes (like comprehensive metabolic panel) which can reduce wait times and improve clinic flow 2
• Ensure proper fasting instructions are given for lipid profile and glucose testing
• Document clearly which tests were ordered at the initial visit to avoid unnecessary duplication at follow-up visits

Common Pitfalls to Avoid

1. Over-testing: Ordering tests without clear clinical indications can lead to unnecessary follow-up testing, patient anxiety, and increased costs
2. Under-testing: Missing important baseline laboratory values may delay diagnosis of common conditions
3. Pre-analytical errors: Ensure proper patient preparation (e.g., fasting status) and sample handling to avoid erroneous results
4. Failure to follow up: Establish a clear protocol for reviewing and acting upon all test results

By following these guidelines for initial laboratory testing, family medicine physicians can establish an important baseline for new patients that facilitates early detection of common conditions and supports ongoing preventive care.