Table 1.
Comparison of clinical and laboratory features between acute interstitial nephritis and acute tubular injury
| Variable | AIN (N=32) | ATI (N=41) | P-value |
|---|---|---|---|
| Clinical features | |||
| Age (years) | 58 (40, 68) | 56 (42, 65) | 0.70 |
| Female | 18 (56%) | 16 (39%) | 0.14 |
| African-American race | 10 (31%) | 9 (22%) | 0.37 |
| Diabetes | 7 (22%) | 9 (22%) | 0.99 |
| Cirrhosis | 0 (0%) | 6 (15%) | 0.02 |
| Acute kidney injury (AKI) | 18 (56%) | 26 (63%) | 0.53 |
| Severe AKI (Stage 2 or higher) | 2 (7%) | 8 (20%) | 0.12 |
| Dialysis at biopsy | 1 (3%) | 4 (10%) | 0.26 |
| Laboratory features at biopsy | |||
| Serum Creatinine, mg/dl | 4.4 (2.8, 6.3) | 4.1 (2.4, 6.7) | 0.71 |
| Blood Urea Nitrogen, mg/dl | 40 (27, 57) | 37 (28, 61) | 0.85 |
| Hemoglobin level, g/dl | 9.8 (8.1, 10.7) | 10.7 (9.3, 12.4) | 0.02 |
| Platelet count (*1000 per mm3) | 247 (202, 290) | 211 (169, 253) | 0.07 |
| Blood eosinophil count | 234 (149, 466) | 198 (95, 400) | 0.24 |
| Urine albumin to creatinine, mg/g | 157 (44, 1452) | 109 (20, 682) | 0.12 |
| Serum bicarbonate level | 19.7 (17, 22.5) | 21 (18.4, 23.9) | 0.29 |
| Urine dipstick | |||
| Specific gravity | 1.015 (1.015, 1.020) | 1.015 (1.015, 1.025) | 0.58 |
| pH | 6 (5.5, 7) | 6 (5.5, 6.5) | 0.02 |
| Protein, ≥2+ | 19 (59%) | 20 (49%) | 0.65 |
| Leukocytes, ≥2+ | 10 (32%) | 11 (28%) | 0.71 |
| Urine Microscopy | |||
| White blood cell, ≥1/HPF | 8 (27%) | 8 (22%) | 0.63 |
| White blood cell cast, ≥1/HPF | 1 (3%) | 1 (3%) | 0.88 |
| RTE cell, ≥1/HPF | 14 (47%) | 12 (32%) | 0.23 |
| RTE cast, ≥1/HPF | 2 (7%) | 4 (11%) | 0.58 |
| Granular cast, ≥1/HPF | 10 (33%) | 17 (46%) | 0.29 |
| Red blood cells, >5/HPF | 5 (29%) | 10 (39%) | 0.54 |
| Red blood cell cast, ≥1/HPF | 0 (0%) | 3 (12%) | 0.14 |
Fisher’s exact test or Wilcoxon Ranksum test. Median (interquartile range) or n (%) shown. HPF, high power field