Acute Post Strep Glomerulonephritis

Clinical presentation

Investigations

Management

Complications

Referral

Discharge

Acute post-strep glomerulonephritis (APSGN) usually occurs 7-21 days after a streptococcal pharyngitis or skin infection (impetigo). APSGN is unusual before the age of 2 years and occurs predominantly in children 3–12 years old. APSGN is caused by an immunological response of the kidney to nephritogenic strains of streptococci, which results in immune complex deposits in the glomerular basement membrane. 

Clinical presentation

• Haematuria (initially macroscopic, then becomes microscopic) 
• Fluid overload with generalised oedema and hypertension, can progress to pulmonary oedema and hypertensive encephalopathy. Beware: Hypertensive encephalopathy and life-threatening pulmonary oedema may occur without being severely fluid overloaded or oedematous. 
• Oliguria, ±anuric renal failure 
• Impetigo is present in >50% of cases. 

Hypertensive crisis: Patient with signs of hypertensive encephalopathy, i.e.: convulsions, retinal haemorrhages, visual loss or left heart failure. 

Hypertensive urgency: Symptomatic patients with significant elevation of blood pressure with complaints of headache, blurred vision and nausea but lacks the above clinical manifestations. 

Investigations 

1. Urinalysis: Macroscopic appearance is smoky, brown, bloody. Dipstick 1+ to 3+ haematuria; trace to 2+ proteinuria). If ≥ 3+ proteinuria may indicate nephritic-nephrotic and require renal referral. 
2. Urine MC&S: Dysmorphic red cells, red cell and granular casts supports diagnosis, culture excludes UTI. 
3. Blood Tests: 
   • Electrolytes and Renal Function: Na, K, Ur, Creat. Repeat daily until renal function stabilised or starting to improve (even if first creat normal) 
   • Acid-base, calcium and phosphate if in renal failure. 
   • Total Protein , Albumin and cholesterol (exclude a Nephritic-nephrotic syndrome) 
   • Streptococcus serology: ASOT, anti-DNAse B (to confirm evidence of Strep infection) 
   • C3 and C4 level (In APSGN C3 reduced, C4 normal. If C3 normal and /or C4 reduced consider another diagnosis) 
4. CXR: Look at heart size, pulmonary oedema, pleural effusions 

Management 

1. Bed rest is necessary in children with severe hypertension or pulmonary oedema. 
2. Weigh daily and record fluid intake and output strictly. 
3. Monitor Blood Pressure: 1-2 hourly BP if raised, half hourly if Nifedipine administered. 
4. Fluid management according to urine output and fluid status : 
   • • Pulmonary oedema plus oliguria/anuria: Do not give any fluid. 
   • • Anuric patient with normal hydration: Replace insensible water losses only (25 mL/kg/day) orally. 
   • • Oliguric patient with normal hydration: Replace insensible water losses plus urine output of previous 24 hours orally. 
   • • Normal urine output with normal hydration: Give normal fluid intake. 
5. Pharmacologic therapy for hypertension (Also see hypertension section under Cardiology) 
   • Acute hypertensive emergency: 
     • Furosemide, IV, 1–2 mg/kg/dose. (If oliguric: 5 mg/kg/dose) Administer IV bolus slowly over 5 min 
     • Labetalol, IV, 0.2–1.0 mg/kg as a bolus (Max 40 mg). Continue infusion: 0.25–3.0 mg/kg/hour. Taper infusion rate up or down according to response. 
   • If no hypertensive crisis but persistent significant hypertension: 
     • Furosemide, IV, 1–2 mg/kg/dose 6 hourly 
     • Propranolol, oral, 1-2 mg/kg/dose, 6 hourly. Max dose: 8 mg/kg/24 hours. 
   • If blood pressure is not adequately controlled: 
     • ADD Amlodipine, oral, 0.2 mg/kg/dose. Max 5 mg. 
     • May be repeated 6 hours later, thereafter once every 24 hours. 
     • Crush 5 mg tablet and disperse in 5 mL water: amlodipine 1 mg/mL. 
   • Once blood pressure has normalised, taper and stop antihypertensive treatment. Monitor blood pressure over the next 48 hours to exclude rebound hypertension. 
6. Eradication of streptococci: Penicillin VK oral, 50 mg/kg/24 hours in 4 divided doses 
7. Dietary measures: Refer to dietician. 
   • • Restrict sodium, potassium intake in all patients. 
   • • Restrict protein intake to 0.5 g/kg/day. 
8. Daily urine dipstix and check if haematuria becomes microscopic 

Complications 

Pulmonary Oedema is life threatening so call for help: 

• Oxygen 
• Sit up or Semi-fowlers position 
• Fluid restrict 
• IV Lasix high dose 3-5 mg/kg IV slowly. 
• Morphine 0,1mg/kg/dose IV 
• Prepare for intubation, contact PICU for transfer 

Refer to the renal team if

Urgent (as soon as possible) 

• Anuric patient with acute volume overload and unresponsive to furosemide. 
• Uncontrolled hypertension. 
• Oliguric and progressive renal failure. 
• Cardiac failure or pulmonary oedema not responding to treatment. 
• Rapid deterioration 

Non-urgent for specialist care 

• Massive proteinuria (nephrotic range) 
• Persistent macroscopic haematuria > 6w or microscopic haematuria>12mo 
• Persistent renal failure after initial recovery. 
• Persistent hypertension 
• Query regarding diagnosis APSGN 
• Any atypical picture, nephritic/nephrotic (significant proteinuria/low albumin) etc 
• Family history of renal disease. 

Discharge when

• Passing urine with microscopic haematuria 
• Resolved oedema, normal BP 
• Normal renal functions