What is CT value in RT-PCR Test ?

CT or Cycle Threshold is the number of cycles, after which the virus in the collected sample is detected in an RT-PCR Test.

Can a person remain RT-PCR positive even after recovery?

Yes. Even in mild cases, RT-PCR can remain positive even after 14 days, although, no real virus can be isolated.

How is it measured?

Viral RNA from the swab sample is converted into DNA, which is amplified through various cycles until a detectable virus level is attained. The number of cycles needed here to detect the virus is the CT value.

What does CT value mean ?

It is inversely proportional to the amount of viral load in the sample. Lower the value, higher the viral load and vice versa. A value lower than 25 means high viral load, and above 25 implies lower viral load.

Does CT value indicate severity?

No. Disease manifestation depends largely on the host body and other factors.

RNA : Ribonucleic Acid

DNA : Deoxyribonucleic Acid

RT-PCR : Reverse Transcription-Polymerase Chain Reaction

Source : ICMR, Dr Rajeev Jayadevan (Scientific Advisor & Post President, Indian Medical Association)

Dr. Debraj Jash
Consultant Pulmonologist
Apollo Multispeciality Hospitals
58 Canal Circular Road, Kolkata 700054
Website : https://drdebrajjash.co.in/
Call : 7044050556/9231918309/8708205139
Email :  jash.debraj@gmail.com