Objectives. The present study was to examine the relationship between serum levels of prolactin and the inflammatory status in drug-naive, first-episode schizophrenia patients with normal weight.

Methods. Patients with normal weight, drug-naive, first-episode schizophrenia and healthy controls were enrolled in the study. Serum levels of prolactin (PRL) were measured using electrical chemiluminescence immunoassay. Serum levels of interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were examined using enzyme-linked immunosorbent assay (ELISA).

Results. Sixty patients with normal weight, drug-naive, first-episode schizophrenia and 60 healthy controls were enrolled. The schizophrenia group had higher serum levels of PRL, IL-1beta, IL-6 and TNF-alpha compared with the control group. There was a gender difference of hyperprolactinemia in schizophrenia group. There were positive relationships between serum levels of PRL and serum levels of IL-1beta, IL-6 and TNF-alpha within the schizophrenia group. Within the schizophrenia group, TNF-alpha was the strongest predictor among the three cytokines for serum levels of prolactin after controlling for gender, age, education, smoking status and disease duration.

Conclusions. Patients with normal weight, drug-naive, first-episode schizophrenia present elevated serum levels of PRL, which might be related to the up-regulated inflammatory status in this patient population.