Rapidly progressive glomerulonephritis (RPGN)’s clinical presentation including acute onset of macroscopic hematuria, decreased urine output, acute onset of hypertension, and edema. Other clinical findings include nephritis presentation on urine analysis with proteinuria, micro and macroscopic hematuria, red blood cells, dysmorphic RBC and RBC casts. Pathological findings characterized extensive crescent formation. Untreated patients can rapidly progress to end-stage kidney disease over a very short periods (days to months). Renal biopsy can further differentiate the types of crescentic glomerulonephritis. There are three major types of RPGN: 1. Anti-glomerular basement membrane (GBM) disease cause by anti-GBM antibodies. It is also associated with pulmonary component with cross-reaction of the antibodies with membrane of the pulmonary capillaries. 1. Immune complexes RPGN associated with immune complexes in the glomeruli such as IgA deposits, antistreptococcal antibodies and subepithelial humps, and antinuclear antibodies and subepithelial deposits in lupus nephritis. 3. Pauci immune RPGN associated with small vessel vasculitis, a necrotizing GN with few or negative immune deposits. It is often antineutrophil cytoplasmic antibody (ANCA) positive. An urgent diagnosis is important in the patient who presenting with clinical findings of RPGN. Serologic tests such as a ANCA, anti-BGM antibodies, ANA, and others with biopsy results. Prompt diagnosis with kidney biopsy and serological test with early therapy is the key to minimize the kidney injury. Specific treatment can be given once the diagnosis is made. Patient is a 51 years old female with history of hypothyroidism and iron deficiency anemia presented with nosebleed and generalized weakness for 2 months. Her baseline creatine was 0.6 back in August 2022. On admission, her creatine was 17.9 along with hyperkalemia which required urgent hemodialysis. Serological studies and renal biopsy were done and confirmed with Pauci Immune Glomerulonephritis with positive P-ANCA, negative anti-GBM antibodies. Patient was treated with IV Solu Medrol 1 gram daily. Hem/Onc was consulted and patient was transferred to Presbyterian [REDACTED] for emergent chemotherapy.