Abstract

INTERPRETING PCR CYCLE THRESHOLD (Ct) VALUES IN CLINICAL DIAGNOSIS BEYOND THE SCOPE OF COVID-19

Aparna J., M.Sc and Amita Ajit, PhD*

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Abstract

The emergence of technology to rapidly and specifically detect early clinical prognosis of diseases, causative pathogens and the rate of infection result in timely therapeutic intervention, driving decisions in patient care and outcomes. This detection is facilitated by reliable, accurate diagnostic tools; of which, reverse transcriptase polymerase chain reaction (RT-PCR) has become prominent. RT-PCR reports cycle threshold (Ct), a numerical value, which is inversely related to the quantity of target genetic material detected in the patient specimen. Even though PCR testing and Ct values provide a deeper clinical understanding of disease prognosis, various limitations surround its interpretation. Ct value being dependent on multiple factors including the sample type and its quality, careful interpretation in relation to clinical findings is required. This review discusses the complexity, challenges and considerations involved in interpreting Ct value at the laboratory setting and its associated use in patient management decisions.

Keywords: Polymerase Chain Reaction, Cycle threshold, Ct Value, Cycle quantification, RT PCR, Clinical diagnostics.