Acute Interstitial Nephritis in the setting of Volume Overload. A Rash Diagnosis? Witt, Lucy MD MPH; Liles Jr., E. Allen MD; Stephens, John R MD Internal Medicine Residency Program University of North Carolina School of Medicine. Chapel Hill, North Carolina

Objectives: Discussion: 1.Identify common medications that can cause acute interstitial nephritis. • All loop diuretics, with the exception of ethacrynic acid, are sulfonamides. (Fig 1) 2.Recognize sulfa-containing drugs that Allergic skin eruptions are common in are not antibiotics. those allergic to these drugs, but acute interstitial nephritis is rare.1 Case: A 49 year-old man presented with • Exfoliative erythroderma is associated with shortness of breath and worsening rash. He sulfonamide allergy reaction, and is had been discharged from the hospital four distinguishable from chronic dermatitis by days earlier after a nine day admission for the predominance of eosinophils.2 cellulitis and heart failure. During that • Vancomycin and sulfonamide antibiotics are known to cause acute interstitial admission he had been diagnosed with Fig 1. Structure of sulfonamide 3 acute interstitial nephritis thought to be Image 1. Rash and Edema antibiotics and diuretics nephritis, therefore it is not surprising that secondary to vancomycin and had this was the first drug thought to be developed a pruritic rash. He was causing his rash. A closer examination of his history indicated that the rash had discharged on oral prednisone and Clinical Course: furosemide. started before the patient was started on The patient was treated for atrial fibrillation vancomycin. His dyspnea progressed to occur with any with metoprolol and amiodarone. He was activity. His diffuse rash became more • It is important for the general internist to diuresed using IV furosemide. His rash remember that all loop diuretics, except pruritic and red. continued to be intensely pruritic and spread ethacrynic acid, are sulfa-containing and to his scalp. The patient’s creatinine therefore carry allergic risks. Objective Findings: increased, and he developed worsened Pulse was 153. Bibasilar crackles were peripheral eosinophilia of 42%. present. Heart was irregularly irregular. He On the second day of admission, furosemide Common Drugs Causing had diffuse, maculo-papular rash with was discontinue and ethacrynic acid was Interstitial Nephritis desquamation, worst on lower extremities, initiated for ongoing diuresis. Subsequently, along with 3+ pitting edema to the knee. the patient’s creatinine fell to 2.7 on Proton Pump Inhibitors discharge from a high of 3.48, and his Labs: Creatnine 3.48 (2.47 four days prior) eosinophil percentage was zero four days NSAIDs WBC 14 , 42% eosinophils after admission. His rash improved Penicillins and Cephalosporins Urinanalysis: WBC and hematuria significantly. He was discharged on oral steroids with a diagnosis of interstitial References Sulfa antibiotics 1. Ives HE. Chapter 15. Diuretic Agents. In: Katzung BG, Masters SB, Trevor AJ, editors. Basic nephritis due to furosemide. & Clinical Pharmacology, 12e. New York, NY: The McGraw-Hill Companies; 2012. 2. Cohen B. Pediatric Dermatology. 7 ed: Elsevier Limited; 2013. Loop and Thiazide diuretics 3. Phipatanaku, Wanda et. al. “Cross-Reactivity Between Sulfonamides and Loop or Thiazide Diuretics: Is it a theoretical or Actual Risk?”. Allergy Clin Immunol. 2000;12(1):26-28.