What is the differential diagnosis for a patient presenting with left posterior calf pain and shortness of breath, currently taking Xarelto (rivaroxaban), with laboratory results showing hypochloremia, metabolic acidosis, normal bilirubin levels, anemia, normal eosinophil count, minimal cardiac troponin elevation, slightly elevated d-dimer, and mildly elevated brain natriuretic peptide (BNP)?

From the Guidelines

For a patient with left posterior calf pain and shortness of breath who is taking Xarelto, I recommend ordering a lower extremity venous Doppler ultrasound and a CT pulmonary angiogram (CTPA) to evaluate for deep vein thrombosis (DVT) and pulmonary embolism (PE). Despite the patient being on anticoagulation therapy with Xarelto, breakthrough thrombosis can occur, as noted in studies such as 1. The slightly elevated d-dimer and minimal cardiac troponin elevation, along with the patient's symptoms, warrant further investigation.

Differential Diagnosis Considerations

• DVT and PE are primary concerns given the patient's symptoms and anticoagulation therapy, with guidance from studies like 1 and 1 emphasizing the importance of prompt diagnosis and treatment.
• Other potential causes of shortness of breath, such as pneumonia or heart failure, should be considered, but the normal troponin and BNP levels make acute coronary syndrome and heart failure less likely, as suggested by 1.
• The patient's metabolic panel showing hypochloremia and metabolic acidosis should be addressed, but these findings do not directly influence the initial diagnostic approach for the presenting symptoms.

Diagnostic Approach

• Lower extremity venous Doppler ultrasound to evaluate for DVT, as it is a non-invasive and effective method for diagnosing DVT, especially in patients with high clinical suspicion.
• CT pulmonary angiogram (CTPA) to evaluate for PE, given its high sensitivity and specificity for detecting PE, especially in patients with suspected PE and intermediate to high clinical probability, as recommended by 1.
• Additional imaging, such as a chest X-ray, may be useful to assess for alternative causes of shortness of breath.
• Laboratory tests, including a complete blood count, prothrombin time (PT), activated partial thromboplastin time (aPTT), and arterial blood gases if hypoxemia is suspected, should be considered to further evaluate the patient's condition and guide management.

Management Considerations

If DVT/PE is confirmed despite Xarelto therapy, consider checking anti-Xa levels to assess medication efficacy and potentially adjusting the anticoagulation regimen, as suggested by studies on anticoagulation management in patients with VTE, such as 1. The choice of anticoagulant and the need for adjustments should be guided by the most recent and highest quality evidence, prioritizing patient outcomes in terms of morbidity, mortality, and quality of life.

From the Research

Differential Diagnosis

The patient's presentation of left posterior calf pain and shortness of breath, while taking Xarelto (rivaroxaban), suggests several possible diagnoses. The laboratory results showing hypochloremia, metabolic acidosis, normal bilirubin levels, anemia, normal eosinophil count, minimal cardiac troponin elevation, slightly elevated d-dimer, and mildly elevated brain natriuretic peptide (BNP) should be considered in the differential diagnosis.

Possible Causes

• Deep Vein Thrombosis (DVT): The patient's symptoms of left posterior calf pain and shortness of breath, combined with the elevated d-dimer, suggest the possibility of DVT 2, 3, 4. Rivaroxaban is commonly used to treat DVT, and the patient's current treatment with this medication should be taken into account.
• Pulmonary Embolism (PE): The patient's shortness of breath and mildly elevated BNP suggest the possibility of PE 2, 3, 4. The elevated d-dimer also supports this diagnosis.
• Venous Thromboembolism (VTE): The patient's symptoms and laboratory results suggest the possibility of VTE, which includes both DVT and PE 2, 3, 5, 4.
• Other Causes: Other possible causes of the patient's symptoms, such as musculoskeletal pain or cardiac conditions, should also be considered.

Laboratory Results

• Hypochloremia and Metabolic Acidosis: These laboratory results may indicate a underlying condition such as renal impairment or gastrointestinal disorder.
• Anemia: This laboratory result may indicate a underlying condition such as blood loss or nutritional deficiency.
• Elevated d-dimer: This laboratory result suggests the possibility of VTE, but can also be elevated in other conditions such as infection or inflammation.
• Mildly Elevated BNP: This laboratory result suggests the possibility of cardiac strain or PE.

Management

The patient's management should be guided by the suspected diagnosis and laboratory results. If VTE is suspected, the patient's current treatment with rivaroxaban should be continued and monitored 2, 3, 5, 4. If other causes are suspected, further evaluation and treatment should be guided by the underlying condition.