Case Published: March 2023
Diagnosis: Pauci-immune, ANCA negative rapidly progressive glomerulonephritis (RPGN)
Case Summary: Let’s break this case down, starting from the HPI. We have a young male patient with no significant medical history who presents with abdominal pain, vomiting, and hematuria with no other symptoms. He is hypertensive and appears unwell on exam, with significant abdominal tenderness on palpation and CVA tenderness. His labs demonstrate severely elevated creatinine of 8.93 mg/dL with hyperphosphatemia. He has an elevated BUN to 119, and with his vomiting, you could consider him uremic. Although we do not have a baseline creatinine on this patient, we can likely assume this is an acute process since this patient was at his clinical baseline prior to this illness developing, and his kidneys are normal sized on RUS.
This patient has an acute nephritis based on his hematuria and high-grade proteinuria. A differential at this point would include a rapidly progressive glomerulonephritis (RPGN) given the assumed rapid rise in creatinine. RPGN is a clinical and pathologic syndrome comprised of: rapid loss of renal function over days to weeks; urine analysis demonstrating nephritis with proteinuria, hematuria (either micro or macroscopic), dysmorphic RBCs, and RBC casts; and histopathological findings of cellular crescent formation in the glomeruli on renal biopsy. An important thing to remember is that RPGN is an umbrella syndrome that encompasses many different diseases, which can be further broken down into immune complex RPGN, pauci-immune RPGN, and anti-GBM associated RPGN. Below is a flow chart with the various disease processes that can present as a RPGN (Figure 1).
Figure 1. Breakdown of rapidly progressive glomerulonephritis (RPGN), pediatric cases
This patient has red blood cells, white blood cells, and nephrotic-range proteinuria. Beware, urine protein-to-creatinine ratios can be falsely elevated in patients with hematuria due to RBC lysis and release of hemoglobin into the urine. In addition, this patient has acute kidney injury associated with uremia and hyperphosphatemia. The next decision point in management of this patient is to consider whether or not this patient requires renal replacement therapy. Let’s review the indications for acute renal replacement therapy, using the “AEIOU”acronym (Figure 2).
Figure 2. Indications for acute kidney replacement therapy (KRT)
Given that his patient had nausea and vomiting with a BUN value of 119, the decision was made to place a temporary dialysis catheter and start acute hemodialysis. Always remember to think about dialysis disequilibrium syndrome with initiation of acute dialysis and aim to reduce BUN by only 30-50% during the first dialysis treatment.
The diagnosis of RPGN should be made as soon as possible to start treatment to stop disease progression, reverse renal injury, and prevent further renal damage. Do not let delay in obtaining a renal biopsy (which helps direct therapy) and do not delay in initiating treatment. Kidney Disease Improving Global Outcomes (KDIGO) recommends pulse methylprednisolone in combination with cyclophosphamide as the initial therapy to induce remission in pauci-immune ANCA negative RPGN.
For more, take a look below:
1.Chapter 9: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Supplement to Kidney International 100, S193–S206, October 2021.
2.Iorember, Franca; Vehaskari, V. Matti. Chapter 22: Rapidly Progressive Glomerulonephritis and vasculitis. Clinical Pediatric Nephrology, Third edition. 2017.
3. Keskinyan, Vahakn Shant; Lattanza, Brittany; Reid-Adam, Jessica. Glomerulonephritis. Pediatr Rev 44 (9):
498–512, September 2023
4.Lizarraga-Mollinedo, Esther; Martínez-Calcerrada, Jose-Maria; Padrós-Fornieles, Cristina. et al. Renal size and cardiovascular risk in prepubertal children. Scientific Reports 9, 5265, March 2019
5. Moorani, Khemchand; Aziz, Madiha; Amanullah, Farhana. Rapidly progressive glomerulonephritis in children. Pak J Med Sci. 38(2):417-425, January 2022.
Case 56 Index
Case 56 Introduction
Case 56 Physical Exam
Case 56 Diagnostic Testing
Case 56 Additional Diagnostic Testing
Case 56 Pathology
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