At times, there are no symptoms of this disease, but when they do occur they are widely varied and can occur rapidly or gradually. When caused by an allergic reaction, the symptoms of acute tubulointerstitial nephritis are fever (27% of patients), rash (15% of patients), and enlarged kidneys. Some people experience dysuria, and lower back pain. In chronic tubulointerstitial nephritis the patient can experience symptoms such as nausea, vomiting, fatigue, and weight loss. Other conditions that may develop include a high concentration of potassium in the blood, metabolic acidosis, and kidney failure. Blood tests About 23% of patients have a high level of eosinophils in the blood. Urinary findings Urinary findings include: * Eosinophiluria: Original studies with Methicillin-induced AIN showed sensitivity of 67% and specificity of 83%. The sensitivity is higher in patients with<unk>  induced by methicillin or when the Hansel's stain is used. However, a 2013 study showed that the sensitivity and specificity of urine eosinophil testing are 35.6% and 68% respectively. * Isosthenuria * Blood in the urine and occasional RBC casts * Sterile pyuria: white blood cells and no bacteria. About 50% of patients with AIN have pyuria. * Nephrotic-range amount of protein in the urine may be seen with NSAID-associated AIN. Low grade proteinuria may be seen in a majority of other causes of AIN. * White blood cell (WBC) casts: Fewer than one in five patients with AIN have WBC casts in urine. Pathology While non-invasive patient evaluation (physical examination, blood and urine testing, imaging studies) can be suggestive, the only way to definitively diagnosis<unk>  is with a tissue diagnosis obtained by kidney biopsy. Pathologic examination will reveal the presence of<unk>  edema and inflammatory infiltration with various white blood cells, including neutrophils, eosinophils, and lymphocytes. Generally, blood vessels and glomeruli are not affected. Electron microscopy shows mitochondrial damage in the tubular epithelial cells, vacuoles in the cytoplasm, and enlarged endoplasmic reticulum. Gallium scan The sensitivity of an abnormal gallium scan has been reported to range from 60% to 100%. A study of Gallium scan in 76 patients 23 with AIN, 8 with biopsy-proven AIN showed an AUC of 0.75. Novel biomarkers Given the challenges with clinical diagnosis of AIN due to lack of clinical features and lack of accuracy of existing tests, there has been significant interest in identifying non-invasive biomarkers for this disease. One study showed that monocyte chemotactic protein-1 (chemokine CCL-2) and neutrophil gelatinase associated lipocalin (NGAL) were higher in patients with AIN than in controls (in this case healthy participants). A more recent study, showed that urine cytokines interleukin-9 and tumor necrosis factor-α were higher in patients with AIN than in controls without AIN who underwent a biopsy for evaluation of acute kidney injury and showed an AUC of 0.79. This study also showed that the biomarkers had higher AUC than the clinician's pre-biopsy impression of AIN and, when added to a model of clinical variables, showed an AUC of 0.84. In a subsequent study, interleukin-9 was also shown to identify patients most likely to respond to corticosteroid therapy.
Interstitial nephritis
Shunt nephritis
Lupus nephritis
Diffuse proliferative nephritis
Acute tubular necrosis
Renal papillary necrosis
Focal proliferative nephritis
Analgesic nephropathy