Acute Kidney Injury: Diagnostic Approach

The diagnostic approach to Acute Kidney Injury (AKI) involves identifying sudden changes in Serum creatinine or urine output. Clinicians use patient history, physical exams, blood and urine tests, and imaging to classify the condition as prerenal, intrinsic, or postrenal to guide fast treatment.

• A twenty-six-year-old previously healthy male presented with persistent fever, cough, and sore throat unresponsive to a five-day course of cefpodoxime. While physical examination was unremarkable for peripheral edema, rash, or arthritis, he demonstrated newly detected severe hypertension measuring one hundred seventy over one hundred ten millimeters of mercury. Laboratory evaluation revealed acute kidney injury with a serum creatinine of two milligrams per deciliter, an estimated glomerular filtration rate of forty-three milliliters per minute, and a urine protein-to-creatinine ratio of four point four. Urinalysis confirmed microscopic hematuria. Infectious and autoimmune serologies demonstrated an antistreptolysin O titer markedly elevated at one to thirty-two hundred, while antinuclear antibodies and complement levels were normal. Renal ultrasonography showed structurally normal kidneys without hydronephrosis. Given the unexplained nephritic picture, a percutaneous renal biopsy was performed, demonstrating an immune complex-mediated, infection-related glomerulonephritis triggered by recent streptococcal pharyngitis through a type three hypersensitivity mechanism.