Procalcitonin

From greek.doctor

Procalcitonin (PCT) is a prohormone for calcitonin, a calcium-regulating hormone. The level of PCT increases in case of some infections. PCT used to look very promising as a tool to distinguish between bacterial infection and other causes of inflammation (as a more specific alternative to CRP), but more recent research have dampened these hopes as it turns out to not be as specific for bacterial infections as previously thought. It's also a very expensive test. Still, it has some clinical uses.

PCT increases 3 - 4 hours after the infection, and peaks after 24 hours. The normal level is < 0,10 µg/L.

Clinical uses

  • For patients treated with antibiotics for infections in intensive care units, a reduction in PCT level by 80% or to < 0,5 µg/L means that discontinuation of the antibiotics is recommended
  • For patients in whom bacterial respiratory tract infection (like pneumonia) is suspected, a PCT level of < 0,25 µg/L means that antibiotics are not recommended, and a PCT level above that means that antibiotics may be recommended

However, using procalcitonin may also lead to overprescription of antibiotics, as many interpret an elevated PCT as a sign of bacterial infection requiring antibiotics, when there are actually many causes of falsely elevated PCT.

Interfering factors

Many conditions can cause falsely elevated PCT levels, including: