Laboratory Tests for a 66-Year-Old Man with Hemolytic Anemia, Diverticulitis, and CAD Presenting with Feeling "Off" and Tachycardia
A comprehensive laboratory panel including complete blood count, cardiac biomarkers, electrolytes, renal function, and hemolysis markers should be ordered immediately for this patient with multiple risk factors presenting with tachycardia and feeling unwell.
Initial Laboratory Evaluation
Cardiac and Vital Assessment
- High-sensitivity troponin (preferably serial measurements) to rule out acute myocardial injury 1
- 12-lead ECG (immediately, especially during symptoms) 1
- Basic metabolic panel (electrolytes, renal function) 1
- BNP or NT-proBNP to assess for heart failure
Hemolysis Evaluation
- Complete blood count with differential and reticulocyte count 1, 2
- Peripheral blood smear (to assess for schistocytes and abnormal RBC morphology) 3, 4
- Hemolysis panel:
- Direct antiglobulin test (Coombs test) to differentiate immune from non-immune hemolysis 4
Additional Tests Based on Clinical Presentation
- Creatinine with estimation of renal function (GFR) 1
- Liver function tests 1
- Thyroid function tests (TSH, free T4) 1
- Glycemic status (HbA1c and/or fasting plasma glucose) 1
- Iron studies (serum iron, ferritin, TIBC, transferrin saturation) 1, 5
- Inflammatory markers (hs-CRP and/or fibrinogen) 1
Rationale and Interpretation
Cardiac Considerations
The patient's history of CAD and current tachycardia with "skipped beats" raises concern for an acute coronary syndrome or arrhythmia. The 2024 ESC guidelines recommend immediate troponin measurement using high-sensitivity assays to rule out acute myocardial injury 1. Serial measurements may be necessary as a single normal value doesn't exclude ACS.
Hemolytic Anemia Evaluation
For a patient with known hemolytic anemia who is feeling unwell, it's critical to assess the current status of hemolysis. Reticulocytosis, increased LDH and unconjugated bilirubin, and decreased haptoglobin are the hallmarks of ongoing hemolysis 3, 4. The peripheral smear can provide clues to the specific type of hemolytic anemia and whether there's an acute exacerbation.
Renal Function
Renal dysfunction increases the likelihood of CAD and negatively impacts prognosis 1. Additionally, patients with CKD are at high risk for further ischemic events 1. Creatinine clearance is essential for medication dosing and risk stratification.
Special Considerations
Anemia and CAD: Anemia is associated with worse prognosis across the spectrum of CAD. The probability of cardiovascular death, MI, or recurrent ischemia increases as hemoglobin falls below 11 g/dL 1.
Hemolytic Crisis: In a patient with known hemolytic anemia, an acute hemolytic crisis can present with tachycardia and feeling unwell. The hemolysis panel will help determine if there's an acute exacerbation.
Arrhythmia Evaluation: The "skipped beats" may indicate premature atrial or ventricular contractions, which can be associated with electrolyte abnormalities, anemia, or cardiac ischemia.
Pitfall to Avoid: Don't attribute all symptoms to hemolytic anemia without ruling out acute cardiac pathology in a patient with CAD history. The feeling of being "off" with tachycardia could represent an acute coronary syndrome requiring immediate intervention.
By systematically evaluating cardiac, hematologic, and metabolic parameters, you can determine whether the patient's presentation represents an exacerbation of hemolytic anemia, an acute cardiac event, or another process related to his multiple comorbidities.