Keyword: Acute Tubulointerstitial Nephritis (ATIN)
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Congress Abstract
Central Asian Journal of Nephrology, 2(2, Suppl. 1), 2026, cajn_A35, https://doi.org/10.63946/cajn/19541
ABSTRACT:
Background & Objective: Acute tubulointerstitial nephritis (ATIN) is a potentially reversible cause of acute kidney injury (AKI). However, when presenting with rapid loss of renal function and fever of unknown origin, ATIN frequently mimics rapidly progressive glomerulonephritis (RPGN). In Kazakhstan, patients presenting with severe renal dysfunction (eGFR <10 mL/min/1.73m²) are frequently denied or delayed from undergoing diagnostic kidney biopsy due to institutional safety concerns, procedural hesitation, and a regional deficit in subspecialized nephropathology services. This abstract demonstrates the critical diagnostic value of renal biopsy in advanced AKI with clinicopathological dissociation and highlights systemic diagnostic barriers in Central Asia.
Case Presentation: A 41-year-old female with no prior history of kidney disease presented in June 2026 with an unexplained persistent fever (37.0–38.0°C). Despite empirical antibacterial therapy ('ex juvantibus'), her fever persisted. Over 8 weeks, serial laboratory testing revealed a dramatic, rapidly progressive decline in kidney function (Table 1): serum creatinine escalated from a baseline of 70 µmol/L (eGFR 96 mL/min/1.73m²) in June 2026 to 130 µmol/L (09.07.2026), 381 µmol/L (31.07.2026), 441 µmol/L (06.08.2026), and peaked at 524 µmol/L (20.08.2026, eGFR 8.6 mL/min/1.73m²). Remarkably, diuresis remained fully preserved, and urinary abnormalities were strikingly mild (proteinuria 0.13–0.60 g/L, absence of active urinary sediment/hematuria). Immunological evaluation showed positive immunoblot reactivity to SS-B, RP11, and Mi-2α; however, classic systemic connective tissue disease criteria were not met, and ANCA, anti-GBM, and C3/C4 levels were unremarkable. Due to severe renal failure (eGFR <10 mL/min), local clinical evaluation in Kazakhstan hesitated to perform a kidney biopsy, categorizing the condition as RPGN vs. ESRD (CKD Stage 5). The patient subsequently traveled to Turkiye (Istanbul) for an urgent ultrasound-guided renal biopsy on August 20, 2026. Light microscopy (22 glomeruli) revealed intact glomeruli without crescents or necrosis, but severe active interstitial inflammation (mononuclear and neutrophilic infiltrate, tubulitis, leukocyte casts) and acute tubular injury, alongside early chronic tubulointerstitial changes. Direct immunofluorescence was negative. Immediate high-dose corticosteroid therapy (IV Methylprednisolone pulse 80 mg followed by oral Prednisolone 32 mg/day with gradual taper) was initiated. Renal function responded dramatically: serum creatinine dropped from 524 µmol/L to 294.1 µmol/L within 7 days (27.08.2026), 218.9 µmol/L (02.09.2026), and reached 148.2 µmol/L (10.09.2026, eGFR 39.0 mL/min/1.73m²), with complete normalization of inflammatory markers (CRP 1.1 mg/L). Hemodialysis was completely avoided.
Conclusions & Policy Implications: Discrepancy between profound renal failure and mild urinary sediment (clinicopathological dissociation) strongly points toward acute tubulointerstitial disease rather than RPGN. Severe reduction in eGFR should not be considered an absolute contraindication to diagnostic kidney biopsy. Without biopsy, this patient would likely have been mislabeled as end-stage renal disease (ESRD) and initiated on lifelong maintenance dialysis. There is an urgent health policy imperative in Kazakhstan to modernize nephrobiopsy protocols, invest in state-of-the-art biopsy technology, and establish dedicated nephropathology training to prevent irreversible progression of treatable renal diseases.
Case Presentation: A 41-year-old female with no prior history of kidney disease presented in June 2026 with an unexplained persistent fever (37.0–38.0°C). Despite empirical antibacterial therapy ('ex juvantibus'), her fever persisted. Over 8 weeks, serial laboratory testing revealed a dramatic, rapidly progressive decline in kidney function (Table 1): serum creatinine escalated from a baseline of 70 µmol/L (eGFR 96 mL/min/1.73m²) in June 2026 to 130 µmol/L (09.07.2026), 381 µmol/L (31.07.2026), 441 µmol/L (06.08.2026), and peaked at 524 µmol/L (20.08.2026, eGFR 8.6 mL/min/1.73m²). Remarkably, diuresis remained fully preserved, and urinary abnormalities were strikingly mild (proteinuria 0.13–0.60 g/L, absence of active urinary sediment/hematuria). Immunological evaluation showed positive immunoblot reactivity to SS-B, RP11, and Mi-2α; however, classic systemic connective tissue disease criteria were not met, and ANCA, anti-GBM, and C3/C4 levels were unremarkable. Due to severe renal failure (eGFR <10 mL/min), local clinical evaluation in Kazakhstan hesitated to perform a kidney biopsy, categorizing the condition as RPGN vs. ESRD (CKD Stage 5). The patient subsequently traveled to Turkiye (Istanbul) for an urgent ultrasound-guided renal biopsy on August 20, 2026. Light microscopy (22 glomeruli) revealed intact glomeruli without crescents or necrosis, but severe active interstitial inflammation (mononuclear and neutrophilic infiltrate, tubulitis, leukocyte casts) and acute tubular injury, alongside early chronic tubulointerstitial changes. Direct immunofluorescence was negative. Immediate high-dose corticosteroid therapy (IV Methylprednisolone pulse 80 mg followed by oral Prednisolone 32 mg/day with gradual taper) was initiated. Renal function responded dramatically: serum creatinine dropped from 524 µmol/L to 294.1 µmol/L within 7 days (27.08.2026), 218.9 µmol/L (02.09.2026), and reached 148.2 µmol/L (10.09.2026, eGFR 39.0 mL/min/1.73m²), with complete normalization of inflammatory markers (CRP 1.1 mg/L). Hemodialysis was completely avoided.
Conclusions & Policy Implications: Discrepancy between profound renal failure and mild urinary sediment (clinicopathological dissociation) strongly points toward acute tubulointerstitial disease rather than RPGN. Severe reduction in eGFR should not be considered an absolute contraindication to diagnostic kidney biopsy. Without biopsy, this patient would likely have been mislabeled as end-stage renal disease (ESRD) and initiated on lifelong maintenance dialysis. There is an urgent health policy imperative in Kazakhstan to modernize nephrobiopsy protocols, invest in state-of-the-art biopsy technology, and establish dedicated nephropathology training to prevent irreversible progression of treatable renal diseases.
