Antistreptolysin “O” (ASO) – Titre Test

Description

Antistreptolysin “O” (ASO) – Titre Test – Accurate Detection of Recent Strep Infection

The Antistreptolysin O (ASO) – Titre Test from Lab Tests Dubai is a specialized blood test that measures antibodies against streptolysin O, a toxin released by Group A Streptococcus (GAS)bacteria—the same bug behind strep throat and skin infections.

While most strep infections are mild, untreated or delayed cases can trigger serious immune complications, including:

• Acute Rheumatic Fever (ARF) – heart valve damage
• Post-Streptococcal Glomerulonephritis (PSGN) – kidney inflammation

This test is essential for:

• Diagnosing recent streptococcal infection when throat swabs are negative
• Evaluating joint pain, carditis, or chorea (signs of rheumatic fever)
• Investigating hematuria, swelling, or high blood pressure (signs of kidney disease)
• Monitoring immune response in children with recent sore throat or impetigo

Using high-precision spectrophotometry, this serum-based test delivers accurate results within just 1 day, helping pediatricians, internists, and cardiologists identify post-strep complications early.

Available with home blood collection, Lab Tests Dubai ensures fast, accurate, and stress-free testing—so you can protect your heart and kidneys after a strep infection.

Why You Need This Test

If you or your child had a sore throat, scarlet fever, or skin infection weeks ago and now have joint pain, fatigue, or dark urine, this test could reveal a dangerous immune overreaction.

You need the ASO Titre Test if:

• You’ve had a recent sore throat or skin infection (impetigo)
• You’re experiencing joint pain, swelling, or fever weeks after illness
• You have shortness of breath, chest pain, or murmurs (heart involvement)
• You notice facial swelling, reduced urine output, or blood in urine
• Your child shows Sydenham’s chorea (involuntary movements)
• You’re being evaluated for acute rheumatic fever or glomerulonephritis

This test helps:

• Confirm recent Group A Strep exposure
• Diagnose ARF or PSGN when culture is negative
• Guide antibiotic or anti-inflammatory treatment
• Prevent long-term heart or kidney damage

Early detection = lifelong organ protection.

Symptoms That Indicate This Test

Consider the ASO Titre Test if you or your child experience:

✅ For Rheumatic Fever (2–4 weeks post-strep):

• Migratory joint pain (knees, ankles, elbows)
• Fever and fatigue
• Heart murmurs, chest pain, or shortness of breath
• Involuntary movements (Sydenham’s chorea)
• Skin nodules or erythema marginatum (rash)

✅ For Post-Strep Glomerulonephritis (1–2 weeks post-skin/strep throat):

• Dark, tea-colored urine (hematuria)
• Swelling in face, hands, or feet (edema)
• High blood pressure
• Reduced urine output
• Fatigue or nausea

✅ For Recent Infection:

• History of strep throat or impetigo
• Scarlet fever rash
• Untreated sore throat with lingering symptoms

These signs may point to post-streptococcal immune disease—and this test helps start life-saving treatment.

Natural Production: How ASO Antibodies Reveal Past Strep Infection

When Group A Streptococcus infects the throat or skin, it releases streptolysin O, a toxin that damages cells.

Your immune system responds by producing antistreptolysin O (ASO) antibodies—a delayed but specific response.

Key Timeline:

• Antibodies rise 1–3 weeks after infection
• Peak at 3–5 weeks
• May remain elevated for 6–12 months

Normal ASO Titre (Adults & Children):

• <200 IU/mL → Generally negative
• 200–400 IU/mL → Mild elevation (possible recent infection)
• >400 IU/mL → High likelihood of recent GAS infection

Important Notes:

• Not all strep infections raise ASO (skin infections often do)
• Negative ASO doesn’t rule out PSGN (use anti-DNase B for skin-related cases)
• Always interpret with clinical symptoms and history

What Happens If Untreated? Risks of Ignoring Post-Strep Complications

Ignoring high ASO levels with symptoms can lead to:

⚠️ Rheumatic Heart Disease – permanent valve damage, heart failure
⚠️ Chronic Kidney Disease – from untreated glomerulonephritis
⚠️ Sydenham’s Chorea – neurological disability
⚠️ Recurrent Infections & Inflammation
⚠️ Sepsis or Endocarditis – in severe carditis

The good news? Most complications are preventable with:

• Prompt penicillin treatment for active infection
• Long-term antibiotic prophylaxis (for rheumatic fever)
• Blood pressure and kidney monitoring

Early testing = prevention of lifelong disability.

How to Prepare for the Test

To ensure accurate results:

✅ No fasting required
✅ Continue your regular medications—but inform your doctor
✅ Inform your doctor of:

• Recent sore throat, skin infection, or scarlet fever
• History of rheumatic fever or kidney disease
• Antibiotic use (may reduce antibody rise)

A serum blood sample is collected via standard draw—available at our labs or via home collection.

Test Overview: Spectrophotometry Method

Interpretation:

• <200 IU/mL → Negative (no recent infection)
• 200–400 IU/mL → Equivocal (repeat if symptomatic)
• >400 IU/mL → Positive (supports recent GAS infection)

Note: Often paired with anti-DNase B for skin-related PSGN.

Benefits of the ASO Titre Blood Test

🔹 Early Detection of Rheumatic Fever
Catch heart-threatening inflammation before damage occurs.

🔹 Kidney Protection
Identify glomerulonephritis early to preserve function.

🔹 Post-Infection Clarity
Know if lingering symptoms are immune-related.

🔹 Guide Antibiotic Prophylaxis
Start long-term penicillin if ARF is confirmed.

🔹 Peace of Mind for Parents
Monitor children after strep throat or impetigo.

If you’re worried about joint pain, heart issues, or kidney problems after a sore throat, the ASO Titre Test gives you the answers you need in just 1 day.