D‑dimer is a protein fragment formed when fibrin clots are broken down in the body.

Elevated levels indicate active clot formation and breakdown.

Clinical uses include:

Supporting diagnosis of DVT and PE.

Monitoring patients with DIC.

Helping rule out thrombotic events in patients with low clinical probability.

The test is performed on a blood sample using immunoassay methods.

It is highly sensitive but not specific—elevated levels can occur in infection, inflammation, pregnancy, or after surgery.

Analyte: D‑dimer fragments in plasma.

Normal Range (varies by lab): < 0.5 µg/mL FEU (Fibrinogen Equivalent Units).

Abnormal Findings:

Elevated D‑dimer: Suggests clotting disorder (DVT, PE, DIC) or secondary causes (infection, trauma, pregnancy).

Normal/low D‑dimer: Helps rule out thrombotic events in low‑risk patients.

Clinical Use:

Provides a rapid screening tool for thrombotic conditions.

Helps guide imaging studies (e.g., Doppler ultrasound, CT angiography).

Monitors coagulation status in critically ill patients.