Manuel Praga, MD
Madrid Spain

Drug-induced AIN

1. In the elderly, the incidence of AIN has increased over the last 10 years. True incidence might be higher as biopsies usually are not performed in elderly patients, and milder forms of AKI typically are not detected.
2. Urine sediment can be used to evaluate drug-induced AIN (leukocyturia in 82% of cases, microhematuria in 67%, leukocyte cast is also suggestive).
3. See Perazella and Markowitz (Nat Rev Nephrology 2010) for a nice review of this topic.
4. Noninvasive diagnostic tests, such as CT scan or renal sonogram, can be used to detect kidney enlargement. Galliam scan positive uptake in DI-AIN and negative in ATN (Linton et al Clin Nephrol, 1985), need more information.
5. Urinary biomarkers MCP-1 severe in AIN (Wu et al CJASN, 2010). Sensitivity of eosinophiluria is relatively low, and specificity is low as well.
6. UTI and RPGN can also have significant eosinophil in urine.
7. Difficult to identify the culprit drug. A significant portion patients 30-70% do not fully recover baseline kidney function.
8. Steroids: contradictory results but no RCTs done. Rossert KI 2001 analyzed 7 studies and there was no difference. González et al KI 2008 reported a multicenter retrospective study and treatment with steroids was analyzed. Group without steroids needed long-term dialysis and had higher creatinine (both statistically significant). Does the timing of steroid initiation affect the response? The patients that received steroids much earlier (<15 days) responded much better in terms of kidney function. Interstitial infiltrates quickly get replaced with fibrosis if not treated with steroids.
9. What about when you cannot stop the offending drug? For example: a patient receives acyclovir for herpetic encephalitis and then gets AIN from the acyclovir (biopsy proven). Can giving steroids along with the drug help? A case presented by speaker showed that they helped. Steroids tapered over 5 weeks and patient recovered.

Post by Dr. Kenar Jhaveri, eAJKD Blog Editor.

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