Procalcitonin (PCT) in Sepsis Diagnosis: Levels, Significance & Clinical Use
02-09-2026 By Beacon Group

Sepsis is whole body inflammatory response to an infection. Sepsis is caused by an immune response triggered by an infection. The infection is most commonly by bacteria, but can also be by fungi, viruses, or parasites. Common locations for the primary infection include: lungs, brain, urinary tract, skin, and abdominal organs. Risk population include young or old age, a weakened immune system from conditions such as cancer or diabetes, and major trauma or burns. 

Epidemiology: Sepsis causes millions of deaths worldwide and it is one of the most common cause of death in people who have been hospitalized. Worldwide the estimated deaths due to sepsis are about 18 million per year. According to a recent report from Times Of India Mumbai 1 out of the 4 patients admitted to ICU are effected with Sepsis and 1 out of the 2 patient with sepsis dies due to the ailment. According to a study by Indian Intensive Care Case Mix and Practice Patterns (INDICAPS) Mortality in patients with sepsis was 42.2%. 
Symptoms: Along with the symptoms related to the provoking causes sepsis is frequently associated with the symptoms like, Fever, or Lower Body Temp. Elevated Heart Rates, rapid breathing, confusion, edema etc. In addition to these decreased urination, high blood sugar, lowering of Blood Pressure as well as dysfunction of Blood coagulation can also occur in varying degree. 

Diagnosis of Sepsis: A blood sample for sepsis can be tested for Evidences of Infection, Clotting Problems, impaired Lever of Kidney, Function, Blood Counts, Impaired Oxygen availability or Electrolyte imbalance. However, in recent past a need for specific biomarkers has been established and it suggests the use of some Biomarkers like, Procalcitonine(PCT), Some Interleukins (IL), adrenomedullin (ADM) and pro-ADM, atrial natriuretic peptide (ANP) and pro-ANP, pro-vasopressin (copeptin), interferon-γ (IFN-γ), triggering receptor expressed on myeloid cells 1 (TREM-1), and resisting. Of these and others, PCT has been the most studied and, in some countries, is now being included in routine clinical practice and guideline.

Procalcitonin (PCT) is a peptide precursor of the hormone calcitonin. Calcitonin is involved with calcium homeostasis. PCT is composed of 116 amino acids and is produced by parafollicular cells (C cells) of the thyroid and by the neuroendocrine cells of the lung and the intestine.

The level of procalcitonin in the blood stream of healthy individuals is below the limit of detection (0.01 µg/L) of clinical assays. The level of procalcitonin rises in a response to a proinflammatory stimulus, especially of bacterial origin. In this case, it is produced mainly by the cells of the lung and the intestine. It does not rise significantly with viral or non-infectious inflammations. With the imbalances that a severe infection with an associated systemic response brings, the blood levels of procalcitonin may rise to 100 µg/L. In serum, procalcitonin has a half-life of 25 to 30 hours. Remarkably the high procalcitonin levels produced during infections are not followed by a parallel increase in calcitonin or a decrease in serum calcium levels.

Measurement of PCT can be used as a marker of severe sepsis and generally grades well with the degree of sepsis, although levels of PCT in the blood are very low. PCT has the greatest sensitivity and specificity for differentiating patients with systemic inflammatory response syndrome (SIRS) from those with sepsis.

PCT levels may be useful to distinguish bacterial infections from nonbacterial infections. It has shown that PCT may help guide therapy and reduce antibiotic use, which can help save on cost of antibiotic prescriptions and drug resistance.