Procalcitonon

Procalcitonin (PCT) is a precursor of the hormone calcitonin and is produced by the thyroid gland under normal conditions. However, in response to a systemic bacterial infection, various tissues start producing PCT, leading to elevated levels in the blood. PCT is a highly specific biomarker for bacterial infections and sepsis.

PCT levels rise rapidly within 2-4 hours of bacterial infection onset. Higher PCT levels correlate with the severity of sepsis and the systemic inflammatory response, providing insight into the patient's condition.

Unlike other inflammatory markers such as C-reactive protein (CRP) or white blood cell count, PCT levels are more specifically elevated in bacterial infections rather than viral infections or non-infectious inflammatory conditions.

PCT assays are useful in guiding the initiation and discontinuation of antibiotic therapy. Elevated PCT levels can indicate the need for starting antibiotic treatment in patients with suspected bacterial infections. Declining PCT levels during treatment suggest a response to antibiotics and can help guide the safe discontinuation of antibiotics, reducing unnecessary antibiotic use and resistance.