Title: Understanding AcuteInterstitial Nephritis: A Modern Family Physician's Guide
Overview: Acute interstitial nephritis (AIN), also known as acute tubulointerstitial nephritis, is an acute kidney disease characterized by renal interstitial inflammatory cell infiltration and tubular lesions. This article delves into the causes, diagnosis, and treatment of AIN, with a focus on drug-induced AIN, which is the most common form.
Understanding AcuteInterstitial Nephritis:
Acute interstitial nephritis (AIN) is a condition caused by various factors, primarily leading to inflammation in the kidney's interstitium and tubular damage. Common causes include drug allergies, infections, autoimmune diseases, malignancies, metabolic disorders, and unknown etiologies. Drug-induced AIN often results from an immune response to medication, leading to tubulointerstitial inflammation.
Diagnosis:
1. Symptoms: - Allergic reactions, such as rash (e.g., multiform erythema and urticaria), fever, peripheral eosinophilia, joint pain, or lymphadenopathy. - Urinary symptoms, including asymptomatic leukocyturia, hematuria, and proteinuria. - Renal dysfunction, often presenting as oliguric or non-oliguric acute renal failure. - Renal tubular dysfunction may cause renal glycosuria, low specific gravity, and low osmolality urine. - Palpable tenderness at bilateral costovertebral angles and costal spine points, and renal percussion tenderness.
2. Investigations: - Routine blood and urine tests, stool tests, liver and kidney function tests, electrolytes, blood glucose, coagulation function, blood gas analysis, urine β2-microglobulin, 24-hour urine protein quantification, urological ultrasound, electrocardiogram, and chest X-ray. - Renal biopsy may be performed if diagnosis is in doubt.
Treatment:
Treatment aims to remove the cause, provide supportive care, prevent complications, and promote renal function recovery.
1. General Treatment: - Discontinue the suspected drug and control infections. - Rest, adequate caloric and protein intake, correction of fluid and electrolyte imbalances, blood pressure control, and treatment of anemia.
2. Immunosuppression: - Early severe cases of drug-induced AIN may benefit from corticosteroids (e.g., prednisone 30-40 mg daily, or 1 mg/kg body weight daily if necessary). - Gradual reduction in dosage over 2-3 months. - For cases not responding to corticosteroids or progressive renal function deterioration, consider cytotoxic drugs like cyclophosphamide (1-2 mg/kg body weight daily). - Continue treatment for 1-2 months, then reduce dosage or use intermittent therapy for up to 1 year.
3. Dialysis Treatment: - Indicated for patients with significantly elevated blood creatinine levels, hyperkalemia, heart failure, pulmonary edema, or other indications for hemodialysis.
Conclusion: Most patients with AIN can recover, but a few may develop chronic kidney disease. Renal failure that does not resolve after 2 weeks and pathologic findings indicating chronicization suggest a poor prognosis. Early diagnosis and appropriate treatment are crucial for managing AIN effectively.