Differentials
Acute glomerulonephritis
SIGNS / SYMPTOMS
May be asymptomatic, presenting symptoms are indistinguishable from AIN.
Will not respond to withdrawal of triggering medication.
INVESTIGATIONS
Urine shows red blood cell (RBC) casts, dysmorphic RBCs, and/or large amounts of proteinuria.
Renal biopsy can distinguish from AIN.
Acute tubular necrosis
SIGNS / SYMPTOMS
May be asymptomatic, presenting symptoms are indistinguishable from AIN.
A history of hypotension, fluid depletion, or exposure to a nephrotoxin known to cause acute tubular necrosis is usually present.
Will not respond to withdrawal of triggering medication.
INVESTIGATIONS
Urine shows sloughed tubular epithelial cells or bland urinary sediment.
Acute vascular injury
SIGNS / SYMPTOMS
Flank pain with gross hematuria is usually present. There may be evidence of vasculitis elsewhere.
Will not respond to withdrawal of triggering medication.
INVESTIGATIONS
Renal blood flow scans or magnetic resonance angiography shows large vessel vascular lesions such as emboli or renal vein thrombosis.
Acute pyelonephritis
SIGNS / SYMPTOMS
Symptoms of fever, chills, flank pain, nausea, and vomiting are present.
Will not respond to withdrawal of triggering medication.
INVESTIGATIONS
Patients have pyuria with positive urine culture. WBC casts may also be present.
Diabetic kidney disease
SIGNS / SYMPTOMS
Nephrotic syndrome is usually present.
Patient usually has a history of diabetes and diabetes-related complications (e.g., retinopathy).
Will not respond to withdrawal of triggering medication.
INVESTIGATIONS
HbA1c is elevated.
Renal biopsy is diagnostic and shows mesangiolysis, glomerulosclerosis, and Kimmelstiel-Wilson nodules.
Focal segmental glomerulosclerosis
SIGNS / SYMPTOMS
Nephrotic syndrome is usually present.
Will not respond to withdrawal of triggering medication.
INVESTIGATIONS
Renal biopsy shows focal and segmental sclerosis of the glomeruli.
Membranous nephropathy
SIGNS / SYMPTOMS
Nephrotic syndrome is usually present.
Malignancy and viral hepatitis are known associations.
INVESTIGATIONS
Renal biopsy shows thickening of basement with subepithelial electron-dense deposits.
Chest x-ray or CT scan may show a mass consistent with a lung tumor or other malignancy.
Stools may be heme-positive in cases of gastrointestinal malignancy.
Hepatitis B and C serologies may be positive.
IgA nephropathy
SIGNS / SYMPTOMS
Hematuria and red blood cell casts are predominant features.
INVESTIGATIONS
Renal biopsy shows IgA deposits on immunofluorescent exam.
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