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Procalcitonin levels predict cyst infections in autosomal dominant polycystic kidney disease, offering a valuable early biomarker to support diagnosis.

Researchers have successfully established thresholds for using procalcitonin as a biomarker for cyst infections in autosomal dominant polycystic kidney disease (ADPKD), according to findings published in Acta Clinica Belgica.

“The diagnosis of cyst infection in ADPKD is difficult,” Francois Jouret, MD, PhD, and colleagues wrote. “[18F]FDG PET/CT imaging is helpful, but early diagnosis remains challenging. Procalcitonin (PCT), a serum biomarker for bacterial infections, has not been evaluated in ADPKD-related cyst infections.”

Dr. Jouret and colleagues conducted a retrospective review to identify patients with ADPKD who were hospitalized and had available PCT measurements. They identified cyst infections and used univariate and multivariate logistic regression analyses to examine the association between PCT and the risk of cyst infection.

The analysis included 104 patients (mean age, 65.5 years), about half of whom (49.0%) had received a kidney transplant. Results also indicated that 16.3% of patients were on chronic dialysis.

Cyst Infections & PCT Levels

Dr. Jouret and colleagues identified cyst infections in 24 cases. [18F]FDG PET/CT was done in 47 patients and detected cyst infection in 17 cases and non-cystic inflammation in 11.

In all patients, CRP levels at admission reached 97.3 mg/L. The study team measured serum PCT levels within 72 hours after admission in 79% of cases, with a median value of 0.47 µg/L. A significant correlation was seen between serum levels of PCT and creatinine at admission (r, 0.37; P<0.05), and PCT levels of more than 0.59 µg/L significantly predicted cyst infection (OR, 6.30; P=0.0047).

Antibiotics were given 48 hours or more prior to PCT measurements in 9 out of 24 patients with cyst infection. The researchers found that PCT levels did not significantly differ between patients given antibiotics (0.98 [range, 0.43–2.19] µg/L) or not (1.42 [range, 0.94–3.81] µg/L; P=0.39). However, higher PCT was associated with cyst [18F]FDG uptake above the pathological threshold (OR, 2.01; P=0.0028).

Based on the findings, Dr. Jouret and colleagues noted that PCT levels of more than 0.59 µg/L within 72 hours after admission are a significant biomarker for cyst infection in patients with ADPKD.