What blood work is indicated for an 85-year-old female with pleuritic chest pain and a tiny left effusion?

Diagnostic Workup for Pleuritic Chest Pain with Tiny Left Effusion in an 85-Year-Old Female

For an 85-year-old female with pleuritic chest pain and a tiny left effusion, the essential blood work should include complete blood count with differential, comprehensive metabolic panel, D-dimer, cardiac biomarkers (troponin), NT-proBNP, and inflammatory markers (ESR, CRP). 1, 2

Initial Diagnostic Approach

• A chest X-ray should be the first imaging study to confirm the presence and size of the pleural effusion 2, 1
• Thoracentesis is indicated for this unilateral pleural effusion to establish etiology, as this will guide appropriate treatment 2, 1
• Standard pleural fluid tests should include:
  • Protein and LDH (to differentiate exudate from transudate using Light's criteria) 2, 1
  • Cell count with differential (lymphocytic predominance suggests tuberculosis, malignancy) 1
  • pH (important if infection is suspected) 2
  • Glucose 1
  • Cytology (essential to rule out malignancy, especially in elderly patients) 2, 1
  • Gram stain and culture (to identify infectious causes) 2
  • AAFB stain and TB culture (particularly important in elderly patients) 2

Blood Work Essentials

• Complete blood count with differential:

  • Elevated WBC may indicate infection or inflammation 1
  • Anemia may suggest chronic disease or malignancy 1

• D-dimer:

  • Critical for ruling out pulmonary embolism, which is the most common potentially life-threatening cause of pleuritic chest pain (found in 5-20% of emergency department presentations) 3, 4
  • A negative D-dimer in a low-risk patient can effectively rule out PE 5

• Cardiac biomarkers:

  • Troponin to rule out myocardial infarction, which can present with pleuritic pain 3, 4
  • NT-proBNP ≥1500 μg·mL−1 strongly supports heart failure as the cause of the effusion 2

• Inflammatory markers:

  • ESR and CRP to assess for inflammatory conditions 2, 6
  • Elevated values suggest infection or inflammatory process 2

• Comprehensive metabolic panel:

  • Assess renal and hepatic function which may contribute to effusion formation 1
  • Albumin levels help evaluate for hypoalbuminemia as a cause of transudative effusion 2

Additional Considerations for Elderly Patients

• Pulmonary embolism should be strongly considered in this age group with pleuritic pain and effusion 7, 5

  • PE-related effusions are usually exudative, often hemorrhagic, and typically occupy less than one-third of the hemithorax 7, 5
  • Dyspnea is often disproportionate to the size of the effusion in PE 5

• Malignancy must be ruled out, as it is a common cause of unilateral effusions in elderly patients 6

  • Only 60% of malignant effusions can be diagnosed by cytological examination 2
  • If initial cytology is negative but suspicion remains high, consider CT thorax with contrast 2

• Heart failure can present with unilateral effusions, particularly on the right side, but left-sided effusions should raise suspicion for alternative diagnoses 2, 1

Common Pitfalls to Avoid

• Not all unilateral effusions in patients with heart failure are due to heart failure; diagnostic thoracentesis is essential to rule out other etiologies 1

• Relying solely on clinical assessment without thoracentesis can lead to missed diagnoses, especially in elderly patients where multiple etiologies may coexist 2, 1

• Failing to consider pulmonary embolism in elderly patients with pleuritic pain, as PE is frequently overlooked in patients with pleural effusion 7