What laboratory tests would you order for a 45-year-old patient with decreased appetite?

Laboratory Tests for a 45-Year-Old Patient with Poor Appetite

For a 45-year-old patient with poor appetite, a complete blood count and comprehensive metabolic panel, including electrolytes, liver enzymes, and renal function tests, should be ordered as the initial laboratory assessment. 1

Initial Laboratory Workup

The American Psychiatric Association (APA) recommends the following laboratory tests for patients presenting with appetite disturbances:

1. Complete Blood Count (CBC)

   • Evaluates for anemia, infection, and other hematologic abnormalities
   • Hemoglobin levels can correlate with appetite status 2

2. Comprehensive Metabolic Panel (CMP)

   • Electrolytes (sodium, potassium, chloride, bicarbonate)
   • Liver function tests (ALT, AST, bilirubin)
   • Renal function tests (BUN, creatinine)
   • Glucose measurement
   • Albumin (important nutritional marker that correlates with appetite) 2

Additional Recommended Tests

1. Thyroid Function Tests

   • TSH, free T4 to rule out thyroid disorders that can affect appetite 3

2. Inflammatory Markers

   • C-reactive protein (CRP)
   • Erythrocyte sedimentation rate (ESR)
   • These can identify inflammatory conditions that may cause decreased appetite 3

3. Lactate Dehydrogenase (LDH)

   • May indicate cellular damage or malignancy 3

4. Urinalysis

   • To screen for renal disease or infection 3

Imaging and Additional Testing

• Chest Radiography

  • Recommended to rule out pulmonary pathology 3

• Fecal Occult Blood Test

  • To screen for gastrointestinal bleeding 3

• Abdominal Ultrasonography

  • May be considered to evaluate for abdominal pathology 3

• Electrocardiogram (ECG)

  • Consider if there are concerns about cardiac issues affecting appetite 1

Clinical Considerations

Potential Causes of Poor Appetite

Poor appetite in a 45-year-old could be due to:

• Malignancy - one of the most common causes of unintentional weight loss and decreased appetite 3
• Gastrointestinal disorders - including gastritis, peptic ulcer disease, H. pylori infection 1
• Psychiatric conditions - depression, anxiety, eating disorders 1
• Medication side effects - polypharmacy can interfere with taste or cause nausea 3
• Metabolic disorders - thyroid dysfunction, diabetes
• Inflammatory conditions - systemic inflammation can trigger anorexia 1

Important Pitfalls to Avoid

• Don't assume age-related anorexia - While appetite decline is common in older adults, a 45-year-old with new-onset poor appetite warrants thorough investigation 4
• Don't overlook medication effects - Review current medications as they may contribute to appetite changes 3
• Don't miss eating disorders - Screen for eating disorders as part of the initial evaluation 1
• Don't delay evaluation - If baseline evaluation is unremarkable, a three- to six-month observation period is justified, but follow-up is essential 3

When to Consider Specialized Testing

If initial laboratory results are unremarkable but symptoms persist, consider:

• Gastroenterology referral for endoscopy if there are alarm symptoms (weight loss, anemia, dysphagia) 1
• Psychiatric evaluation if screening suggests mental health concerns 1
• Nutritional assessment including body mass index (BMI) and other anthropometric measurements 2

By following this systematic laboratory approach, you can effectively identify the underlying cause of poor appetite in your 45-year-old patient and develop an appropriate treatment plan to address the root cause and prevent complications.