What labs are recommended for the evaluation of retinal hemorrhage?

Laboratory Evaluation for Retinal Hemorrhage

For patients with retinal hemorrhage, a comprehensive laboratory workup should include complete blood count, coagulation studies, inflammatory markers, and metabolic testing to identify underlying systemic causes and guide appropriate management.

Initial Diagnostic Approach

The evaluation of retinal hemorrhage requires both ophthalmic examination and laboratory testing to determine the underlying cause, which is essential for appropriate management and prevention of vision loss. The laboratory workup should be tailored based on clinical presentation and suspected etiology.

Essential Laboratory Tests

1. Complete Blood Count (CBC)

   • Evaluates for thrombocytopenia or other hematologic abnormalities
   • Includes hemoglobin, hematocrit, white blood cell count, and platelet count

2. Coagulation Studies

   • Prothrombin time (PT) and International Normalized Ratio (INR)
   • Activated partial thromboplastin time (APTT)
   • These tests help identify bleeding disorders that may contribute to retinal hemorrhage 1

3. Inflammatory Markers

   • Erythrocyte sedimentation rate (ESR)
   • C-reactive protein (CRP)
   • Critical for patients over 50 years to screen for giant cell arteritis 2

4. Metabolic Testing

   • Fasting blood glucose
   • Hemoglobin A1C
   • Lipid panel
   • Chemistry panel
   • These tests help identify diabetes, hyperlipidemia, and other metabolic disorders associated with retinal hemorrhage 2

Additional Testing Based on Clinical Presentation

For Suspected Vascular Causes

1. Cardiovascular Assessment

   • Electrocardiography (ECG)
   • Consider prolonged cardiac monitoring (inpatient telemetry or Holter monitor) if initial evaluation is unclear 2

2. Vascular Imaging

   • Carotid ultrasound/transcranial Doppler
   • Consider MRA or CTA of cervicocephalic vessels 2

3. Echocardiography

   • Transthoracic echocardiography to evaluate for cardiac sources of emboli
   • Consider transesophageal echocardiography for better visualization of left atrial thrombus, patent foramen ovale, aortic arch atherosclerosis, and valvular disease 2

For Suspected Thrombophilia

1. Thrombophilia Screening
   • Protein C and Protein S levels
   • Activated protein C resistance
   • Factor V Leiden mutation
   • Factor VIII activity 3

For Suspected Arteritic Causes

1. Temporal Artery Biopsy
   • Consider in patients over 50 with elevated ESR/CRP and symptoms suggestive of giant cell arteritis 2

Special Considerations

Age-Related Considerations

• Patients over 50 years: Prioritize ESR and CRP to rule out giant cell arteritis, which requires immediate steroid therapy to preserve vision in the contralateral eye 2
• Younger patients: Consider thrombophilia workup, as activated protein C resistance appears to be more common in younger patients with retinal vascular occlusions 3

Timing of Laboratory Testing

• Acute presentation: Laboratory testing should be performed urgently, especially for suspected arteritic causes 2
• Non-acute presentation: Laboratory testing can be performed on an outpatient basis

Clinical Pearls and Pitfalls

Pearls

• Always consider giant cell arteritis in patients over 50 years with retinal hemorrhage, as prompt treatment is essential to prevent vision loss in the contralateral eye
• A normal ESR does not completely rule out giant cell arteritis; clinical judgment is essential
• Consider both ocular and systemic causes of retinal hemorrhage

Pitfalls

• Delaying evaluation for giant cell arteritis can lead to irreversible vision loss
• Focusing solely on ocular causes without considering systemic disorders
• Overlooking coagulation disorders as potential contributors to retinal hemorrhage

Conclusion

Laboratory evaluation for retinal hemorrhage should be comprehensive and guided by clinical presentation. Early identification of underlying causes is essential for appropriate management and prevention of vision loss. In cases of acute retinal ischemia, urgent evaluation and management are critical to preserve vision and prevent systemic complications.

Remember that laboratory testing should complement, not replace, a thorough ophthalmic examination including fundus photography, optical coherence tomography, and possibly fluorescein angiography to document the extent and characteristics of retinal hemorrhage 4.