Dengue blood-test timeline — Quick takeaways for patients

A closer look at what’s happening inside your body

1. Two kinds of dengue blood tests

2. Platelets and hematocrit: the leakage story

• Platelets are cells that help your blood clot.

  • They often drop sharply between Days 4-6 (sometimes to <50 × 10⁹/L).

• Hematocrit is the percentage of red blood cells in your blood.

  • When plasma leaks out of tiny vessels, your blood becomes “thicker,” so hematocrit rises (≥20 % above your usual value).

• Why it matters: The combination of falling platelets and rising hematocrit is the strongest laboratory warning that you might slip into shock or serious bleeding. This is why doctors repeat CBCs daily—or even twice daily—around Day 4-6.

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3. The three clinical phases

4. Why secondary dengue can be trickier

If you’ve had dengue before (even years ago) your IgG antibodies jump up very early in the new infection. That early surge can accidentally help the virus enter cells (a process called antibody-dependent enhancement), making plasma leakage more likely. Result: monitoring is even more crucial. Doctors may admit you sooner, even if your platelet count is not yet low.

5. Practical tips for patients & families

1. Don’t wait to test: An early NS1/PCR saves days of uncertainty.

2. Track your own “platelet trend” if you get outpatient CBCs—downward slopes matter more than single numbers.

3. Fluid intake: Sip oral rehydration or salted soups. Aim for pale-yellow urine.

4. Avoid NSAIDs: Ibuprofen, aspirin, and diclofenac can worsen bleeding. Stick to paracetamol for fever.

5. Red-flag symptoms (go to hospital immediately):

   • Sudden severe abdominal pain

   • Continuous vomiting

   • Bleeding from nose or gums, black stools, or red urine

   • Feeling faint, cold extremities, or restlessness after the fever subsides

6. After recovery: Your IgG stays positive for life. Carry a copy of your dengue report; it helps doctors interpret future serology correctly.

   
   

Take-home message

Dengue is usually self-limiting—but timing is everything. Early testing confirms the diagnosis, and close monitoring of platelets and hematocrit around Days 4-6 catches complications before they turn serious. Stay hydrated, avoid anti-inflammatory painkillers, and never ignore warning signs once the fever starts to fade.