Abstract: SA-PO0117
Diagnostic Utility of Renal Hypertrophy on CT Imaging for Differentiating Acute Interstitial Nephritis from Other Causes of AKI
Session Information
- AKI: Clinical Diagnostics and Biomarkers
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Tanabe, Jun, Sei Marianna Ika Daigaku, Kawasaki, Kanagawa Prefecture, Japan
- Yazawa, Masahiko, Sei Marianna Ika Daigaku, Kawasaki, Kanagawa Prefecture, Japan
- Ogata, Masatomo, Sei Marianna Ika Daigaku, Kawasaki, Kanagawa Prefecture, Japan
- Shibagaki, Yugo, Sei Marianna Ika Daigaku, Kawasaki, Kanagawa Prefecture, Japan
Background
Early treatment of acute interstitial nephritis (AIN) is effective; however, kidney biopsy, the gold standard for diagnosis, is often unfeasible in critically ill patients. Although kidney hypertrophy is a well-recognized feature of AIN, its diagnostic utility remains unclear. We evaluated CT-based kidney hypertrophy as a non-invasive AIN predictor.
Methods
We retrospectively analyzed 40 adults who undergoing kidney biopsy for AKI (2010-2024) with pre- and post-AKI CT scans (AIN=16; non-AIN=24). Kidney hypertrophy rate was defined as the percentage increase in kidney volume. We evaluated five predictors: the classic triad, urinary white blood cells >10/high-power field, peripheral eosinophils >500/μL, drug exposure (antibiotics, nonsteroidal anti-inflammatory drugs, or proton pump inhibitors), and kidney hypertrophy >20%. A logistic regression model and weighted diagnostic score were constructed, and discrimination was assessed using the area under the receiver operating characteristic curve (AUC).
Results
There was no significant difference in age (67.7 vs. 65.6 years) or estimated glomerular filtration rate (26.8 vs. 23.7 mL/min/1.73 m2) between the groups. The AIN group had higher eosinophils (477 vs. 153/µL, P = 0.02), triad positivity (56% vs. 25%, P=0.046), and kidney hypertrophy (140.0 vs. 108.8 %, P < 0.01). Stepwise variables inclusion increased the AUC to 0.85 with all five predictors. A scoring system (range 0–4.5; triad 0.5, eosinophils 1, drug exposure 1, hypertrophy 2) showed good discrimination. At a cutoff of 2.5, sensitivity was 75.0%, specificity 79.2%, positive predictive value (PPV) 70.6%, and negative predictive value 82.6%. A score ≥4.0 yielded 100% specificity and PPV (Figure).
Conclusion
Kidney hypertrophy rate was 40% in AIN patients. A combined clinical-imaging score showed good discrimination, potentially aiding early diagnosis when biopsy is unfeasible.