From the Guidelines
The most reliable test for diagnosing early or subclinical acute rejection is US-guided biopsy [ 1 ]. This method is considered the standard for diagnosis of rejection and evaluation of immunosuppression, as it allows for direct examination of the graft tissue.
Key Points
- US-guided biopsy has a low complication rate, with a reported rate of 0.4% to 1% graft loss in approximately 2,500 biopsies [ 1 ].
- Other imaging modalities, such as duplex Doppler US, have limited sensitivity and specificity in identifying the cause of functional transplant dysfunction [ 1 ].
- Renal segmental or intralobar artery resistive indices (RI), measured by duplex Doppler US, are not reliable in identifying the cause of functional transplant dysfunction, with a sensitivity of 13% and a specificity of 100% [ 1 ].
- CT and CTA may be useful in evaluating renal masses, perinephric fluid collections, and posttransplant lymphoproliferative disease, but have limited data on their usefulness in evaluating transplant vascular complications [ 1 ].
From the Research
Diagnostic Biomarkers for Acute Rejection
The most reliable test for diagnosing early or subclinical acute rejection involves the use of biomarkers. Key findings include:
- Urinary kidney injury molecule-1 (KIM-1) is a sensitive and specific biomarker for early detection of kidney injury 2, 3, 4, 5, 6
- KIM-1 levels in urine can detect kidney damage earlier than traditional biomarkers such as plasma creatinine and blood urea nitrogen (BUN) 2, 3
- KIM-1 has been qualified by the Food and Drug Administration and European Medicines Agency as a biomarker to monitor drug-induced kidney injury 3
Detection Methods
Various detection methods have been developed for urinary KIM-1, including:
- Enzyme-linked immunosorbent assay (ELISA) 2, 4
- Immunochromatographic lateral flow assay 3
- Colloidal gold immunochromatographic strips 4
- These methods offer rapid and sensitive detection of urinary KIM-1, with some allowing for detection within 5-10 minutes 4 or 15 minutes 3
Clinical Applications
Urinary KIM-1 has potential clinical applications in: