From the Guidelines
A D-dimer level of 1.51 μg/mL is concerning and warrants further medical evaluation, as it is elevated above the normal range (typically <0.50 μg/mL). This elevation could indicate the presence of abnormal blood clotting in the body, such as deep vein thrombosis (DVT) or pulmonary embolism (PE) 1. However, D-dimer can also be elevated in many other conditions including pregnancy, recent surgery, infection, inflammation, cancer, or advanced age.
Clinical Significance
The clinical significance of a D-dimer level of 1.51 μg/mL depends on the context, including the patient's symptoms, medical history, and risk factors. According to the American College of Physicians, clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered 1.
Diagnostic Approach
If you have this result, you should contact your healthcare provider promptly for evaluation, especially if you're experiencing symptoms like leg pain/swelling, chest pain, or shortness of breath. Your doctor will likely consider your clinical presentation, risk factors, and possibly order additional tests such as ultrasound or CT scans to determine if a blood clot is present 1.
Importance of Clinical Judgment
It's essential to understand that while an elevated D-dimer raises concern, it's not specific enough to diagnose a clot on its own - it's more valuable as a screening tool when negative, as it can help rule out clotting disorders 1. Clinicians should use age-adjusted d-dimer thresholds (age × 10 ng/mL rather than a generic 500 ng/mL) in patients older than 50 years to determine whether imaging is warranted 1.
Next Steps
Patients with a D-dimer level of 1.51 μg/mL should undergo further evaluation, including a thorough medical history, physical examination, and possibly additional diagnostic tests, to determine the cause of the elevated D-dimer level and to rule out or confirm the presence of a blood clot. This approach will help minimize the risk of morbidity and mortality associated with blood clots, while also avoiding unnecessary testing and treatment in patients without a clot.
From the Research
D-Dimer Levels and Concerns
- A D-dimer level of 1.51 may be concerning, as it is above the typical threshold for ruling out pulmonary embolism (PE) or deep vein thrombosis (DVT) in patients with low clinical pretest probability 2.
- However, the concern level depends on the clinical context, including the patient's symptoms, medical history, and other diagnostic test results.
Comparison to Study Thresholds
- A study found that a D-dimer threshold of < 0.5 μg mL(-1) was used to rule out PE in patients with unlikely probability, while a threshold of < 1.0 μg mL(-1) was used for patients with low clinical probability 2.
- Another study suggested that a D-dimer level of < 1000 ng per milliliter could be used to rule out PE in patients with low clinical pretest probability, and < 500 ng per milliliter for those with moderate clinical pretest probability 3.
- In comparison, a D-dimer level of 1.51 is above these thresholds, which may indicate an increased risk of thrombotic events.
Association with Thrombotic Events
- Elevated D-dimer levels have been associated with an increased risk of major adverse cardiovascular events (MACE) and non-CABG major bleeding in patients with acute myocardial infarction 4.
- A study also found that a transient increase in D-dimer levels after anticoagulant therapy was correlated with thrombus changes and thrombolysis at 30 days in patients with pulmonary embolism 5.