22 year old female no co morbidies came with facial puffiness for 1 week, limb edema 3 days, breathlessness since 1 day. No fever cough, chest pain. O/e bp 150/90 rest all vitals normal. Edema + ,pallor,+. Minimal abd wall edema +, periorbital fullness+. Labs anemia+. Urine protine 1+. Rest lft, rft, rlecg normal. Cxr b/l lower zone haziness+. H/o fever sore throat 1 month ago and sore throat 15 days ago+ . How should further evaluate?
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Clinical Evaluation: Likely Post-Streptococcal Glomerulonephritis (PSGN) / Acute Nephritic Syndrome
Working Diagnosis
This presentation is classic Acute Nephritic Syndrome most likely secondary to Post-Streptococcal Glomerulonephritis (PSGN):
| Feature | This Patient |
|---|---|
| Age / Sex | 22F (typical range 2-18y, but occurs in young adults) |
| Antecedent throat infection | Two episodes: 1 month and 15 days ago |
| Latent period | 7-10 days after pharyngitis (fits perfectly) |
| Edema | Periorbital + facial + limb + abdominal wall |
| Hypertension | 150/90 |
| Urine protein | 1+ (non-nephrotic range - typical for nephritic) |
| Anemia | Present |
| CXR bilateral lower zone haziness | Suggests volume overload / pulmonary edema |
- Goldman-Cecil Medicine notes: PSGN is immune complex-mediated GN following Group A streptococcal throat/skin infection with a latent period of 7-10 days for pharyngitis. Presentation is hematuria, edema, hypertension, oliguria - this fits. - Comprehensive Clinical Nephrology, p. 243: In nephritic syndrome, proteinuria is rarely in nephrotic range, serum albumin is normal, and circulating volume increases causing hypertension and pulmonary edema - exactly as seen here.
Further Evaluation: Step-by-Step
1. CONFIRM STREPTOCOCCAL INFECTION (Most Important)
| Test | What to look for | Notes |
|---|---|---|
| ASO titer (Anti-Streptolysin O) | Elevated (>200 Todd units) | Rises 7-14 days after pharyngitis, peaks 3-4 weeks |
| Anti-DNase B | Elevated | More sensitive for throat infection; stays elevated longer |
| Anti-hyaluronidase | Elevated | Supplementary; confirms recent strep infection |
| Throat swab culture | Group A beta-hemolytic streptococci | Useful if active sore throat still present |
| Rapid strep test (RADT) | Positive for Strep pyogenes | Quick bedside tool |
Serial rising titers are more significant than a single determination. - Tietz Textbook of Laboratory Medicine, p. 1886
2. CONFIRM COMPLEMENT ACTIVATION
| Test | Expected finding | Significance |
|---|---|---|
| Serum C3 | LOW | Most characteristic - activation of alternate complement pathway |
| Serum C4 | Normal (in PSGN) | If C4 also low, think SLE or MPGN |
| CH50 | Low | Total hemolytic complement reduced |
Goldman-Cecil: "The serum complement level, especially C3, is low" in PSGN. C3 typically normalizes within 8-12 weeks.
3. URINALYSIS & URINE MICROSCOPY (Mandatory)
| Test | Expected finding |
|---|---|
| Urine microscopy | Red cell casts (pathognomonic of glomerulonephritis) |
| Dysmorphic RBCs (acanthocytes) | Confirms glomerular origin of hematuria |
| Urine protein: creatinine ratio (UPCR) | Quantify proteinuria (nephrotic threshold >3.5g/day) |
| 24-hour urine protein | Quantify - expect <3.5g/day in nephritic |
| Urine specific gravity / osmolality | Assess concentrating ability |
| Urine sodium | Low FENa if volume-depleted GFR |
Note: The urine dipstick shows 1+ protein - this is non-nephrotic range, consistent with nephritic syndrome. Importantly, hematuria may be microscopic or macroscopic (cola/tea-colored urine - ask specifically).
4. RENAL FUNCTION & METABOLIC PANEL
| Test | Why needed |
|---|---|
| Serum creatinine / BUN | Baseline - to detect any azotemia |
| eGFR | Quantify kidney function |
| Serum electrolytes (Na, K, Cl, HCO3) | Detect hyperkalemia, acidosis |
| Serum albumin | Normal in nephritic, low in nephrotic |
| Uric acid | May be elevated due to reduced GFR |
5. EXCLUDE OTHER CAUSES (Differential Diagnosis Workup)
Since this is a 22-year-old female with edema and hypertension, SLE is a critical differential and must be excluded:
| Test | For |
|---|---|
| ANA (Anti-nuclear antibody) | Screen for SLE |
| Anti-dsDNA antibody | SLE-specific (high specificity) |
| Anti-Sm antibody | SLE-specific |
| C3, C4 | Both low in SLE-GN (Class III/IV lupus nephritis) |
| ANCA (c-ANCA, p-ANCA) | Vasculitis (GPA, MPA) |
| Anti-GBM antibody | Goodpasture's syndrome |
| Hepatitis B surface antigen (HBsAg) | Membranoproliferative GN |
| Hepatitis C antibody | Cryoglobulinemic GN |
| Cryoglobulins | If hep C positive |
| Serum protein electrophoresis (SPEP) | Myeloma (less likely at this age) |
The serologic table from Tietz (Table 49.13) specifically highlights ANA/anti-dsDNA for SLE, ANCA for vasculitis, and anti-GBM for Goodpasture's as the key discriminating tests.
6. IMAGING
| Study | Purpose |
|---|---|
| Renal ultrasound | Kidney size and echogenicity; enlarged echogenic kidneys suggest acute GN; exclude obstruction |
| Chest X-ray (already done) | Bilateral lower zone haziness - likely pulmonary edema from volume overload - monitor |
| Echocardiogram | If concerned about cardiac involvement (less likely here) |
7. ASSESS SEVERITY / MONITOR FOR COMPLICATIONS
| Test | Complication to detect |
|---|---|
| ECG (already normal) | Hyperkalemia-related arrhythmia |
| Repeat serum K+ | Hyperkalemia (if oliguric) |
| Blood gas (ABG/VBG) | Metabolic acidosis |
| Daily urine output monitoring | Oliguria (<400 mL/day = severe) |
| Daily weight | Monitor fluid overload |
| Fundus examination | Hypertensive retinopathy grade |
8. RENAL BIOPSY - When to Consider?
Not needed routinely in classic PSGN, but indicated if:
- No evidence of antecedent strep infection (ASO/DNase B negative)
- C3 does NOT normalize within 8-12 weeks
- Rapidly deteriorating renal function (RPGN pattern)
- Nephrotic-range proteinuria develops
- Diagnostic uncertainty remains after serology
- Strong suspicion of SLE nephritis (young female with multi-system features)
Goldman-Cecil: "Renal biopsy is rarely necessary, but it should be considered when there is diagnostic doubt."
Priority Order for Workup
- Urine microscopy - look for RBC casts (confirms GN)
- ASO titer + Anti-DNase B - confirm strep etiology
- Serum C3, C4, CH50 - complement profile
- ANA, anti-dsDNA - exclude SLE (young female, mandatory)
- Serum creatinine, electrolytes, albumin - severity
- Renal ultrasound - structural assessment
- ANCA, anti-GBM - if atypical features or rapidly worsening
Quick Differential Diagnosis Summary
| Diagnosis | Key distinguishing feature |
|---|---|
| PSGN (most likely) | +ASO, low C3 normal C4, antecedent pharyngitis |
| SLE nephritis | ANA+, anti-dsDNA+, both C3 and C4 low, young female |
| IgA nephropathy | Concurrent (not post-) hematuria with URTI, normal complement |
| MPGN | Persistent low C3+C4, chronic course |
| Goodpasture's | Hemoptysis, anti-GBM+, no strep history |
| ANCA vasculitis | ANCA+, systemic vasculitis features |
Clinical Note
The bilateral lower zone haziness on CXR in the context of hypertension and edema indicates pulmonary congestion/early pulmonary edema - this means the patient may need urgent loop diuretic therapy while investigations are being sent. Do not delay treatment while awaiting results if there is respiratory distress.
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