PA27.1-7 | Renal Pathology I: Glomerular Disease & Renal Failure — Case Study

CLINICAL SCENARIO

A 7-year-old boy presents with progressive periorbital and pedal oedema for 3 weeks. Urinalysis reveals heavy proteinuria (4+) and no haematuria. You will classify his renal syndrome, interpret laboratory and biopsy findings, establish a specific diagnosis, and reason through management and long-term renal consequences. Consistent clues are embedded at each step — build systematically on earlier answers.

Section 1 — Syndrome Classification (PA27.1)

The boy has 4+ proteinuria (urine protein:creatinine ratio 8.2), serum albumin 1.4 g/dL, total cholesterol 520 mg/dL, and no haematuria or hypertension. Classify his presentation as nephrotic or nephritic syndrome. List the four cardinal features that define the syndrome he has, and explain the pathophysiological link between glomerular protein leak, hypoalbuminaemia, and oedema formation.

Guidance: Expected: nephrotic syndrome; four features = massive proteinuria (>3.5 g/day in adults or >40 mg/m²/hr in children), hypoalbuminaemia, peripheral oedema, hyperlipidaemia/lipiduria. Mechanism chain: loss of glomerular charge-barrier → proteinuria → ↓oncotic pressure → oedema + hepatic lipoprotein upregulation. ~150 words.

Section 2 — Urinary Findings & Initial Work-Up (PA27.2)

Urine microscopy: oval fat bodies, fatty casts, no red cell casts. Urine dipstick: protein 4+, glucose negative, blood trace. Serum complement C3 and C4 are normal. No recent sore throat or skin infection. Interpret each urinary finding and explain why haematuria and red cell casts are absent. What does the normal complement level tell you about the likely pathological process?

Guidance: Oval fat bodies and fatty casts = lipiduria, confirms massive proteinuria; absent red cell casts distinguish nephrotic from nephritic pattern; normal complement rules out post-infectious GN (low C3) and SLE (low C3+C4), pointing toward primary podocyte disease (MCD or FSGS). ~120 words.

Section 3 — Glomerular Pathology: LM, IF, and EM (PA27.3, PA27.4)

A renal biopsy is deferred because the patient is a first-presentation child aged 7 with classic nephrotic syndrome. Instead, a steroid trial is started. He achieves complete remission within 10 days. Predict the most likely biopsy findings had tissue been taken: describe what you would expect on (a) light microscopy (LM), (b) immunofluorescence (IF), and (c) electron microscopy (EM) for the most probable diagnosis. Then contrast these findings with what you would expect in FSGS, providing one distinguishing feature for each modality.

Guidance: MCD: LM — normal glomeruli; IF — negative/minimal staining; EM — diffuse foot-process effacement (diagnostic). FSGS contrast: LM — segmental sclerosis in some glomeruli; IF — IgM/C3 in sclerosed segments; EM — foot-process effacement + hyaline deposits. Steroid responsiveness strongly favours MCD in this age group. ~200 words.

Section 4 — Specific Diagnosis & Pathogenesis (PA27.3, PA27.5)

Based on your findings in Sections 1–3, state the specific diagnosis with justification (age, clinical features, steroid response, predicted biopsy). Briefly explain the current pathogenic hypothesis for this condition, including the role of T-cell-derived circulating permeability factors and their effect on the podocyte slit-diaphragm.

Guidance: Diagnosis: Minimal Change Disease (MCD). Pathogenesis: T-cell dysfunction → circulating factor (possibly CD80 upregulation / podocin disruption) → loss of slit-diaphragm integrity → charge and size barrier failure → proteinuria. Emphasise the functional rather than structural lesion at LM level. ~150 words.

Section 5 — Progression to Renal Failure & Uraemic Complications (PA27.6, PA27.7)

The patient relapses three times over two years and eventually develops steroid dependency. A repeat biopsy now shows segmental sclerosis in 30% of glomeruli, consistent with secondary FSGS. His eGFR declines from 110 to 58 mL/min/1.73m² over the next 5 years. (a) Classify his current CKD stage. (b) Explain the histological mechanism by which focal glomerulosclerosis leads to progressive nephron loss and CKD (include the role of glomerular hypertension and TGF-β). (c) List four uraemic complications he is at risk for, with a brief pathophysiological basis for each.

Guidance: CKD Stage 3a (eGFR 45–59). Mechanism: nephron loss → hyperfiltration in remaining glomeruli → glomerular HTN + TGF-β-driven mesangial matrix expansion → further sclerosis → progressive nephron loss (vicious cycle). Uraemic complications (any 4): anaemia (↓EPO), renal osteodystrophy (↓1,25-(OH)₂D₃ + secondary hyperPTH), hyperkalaemia, metabolic acidosis, uraemic pericarditis, encephalopathy. ~200 words.

Section 6 — Integrated Summary & Reflection (PA27.1–PA27.7)

Write a concise clinico-pathological summary (≤150 words) that connects: (1) the initial syndrome, (2) the underlying podocyte pathology, (3) the disease course and steroid response, and (4) the eventual progression to CKD. Close with one sentence reflecting on what this case taught you about the clinical significance of distinguishing nephrotic from nephritic syndrome at first presentation.

Guidance: Look for a coherent narrative arc: syndrome recognition → pathological basis → treatment prediction → long-term consequence. Reward integration across all earlier sections. Deduct marks if the summary contradicts answers in earlier sections. ~150 words for summary + 1 sentence reflection.

PEER REVIEW

You will be assigned one classmate's submission to review. Read all six sections before writing any feedback.

What to assess:
1. Is the syndrome correctly classified in Section 1, and is the mechanistic chain complete?
2. Are the urinary findings in Section 2 accurately interpreted? Is the complement reasoning logical?
3. In Section 3, do the predicted biopsy findings match the clinical context? Is the MCD vs FSGS contrast meaningful?
4. Does Section 4 name the correct diagnosis and provide an appropriate pathogenesis explanation?
5. In Section 5, is the CKD stage consistent with the eGFR given? Are uraemic complications explained (not just listed)?
6. Does the Section 6 summary build a coherent narrative from earlier sections without contradicting them?

How to give feedback:
- Write 2–3 sentences of specific, constructive feedback per section.
- Note one strength and, where applicable, one area for improvement.
- Avoid vague statements like "good job" or "needs more detail" — point to the specific finding or step.
- Tone: collegial and constructive. You are a learning partner, not an examiner.

Length: 200–300 words total. Submit your review within 48 hours of receiving the assignment.