Serum copeptin and its diagnostic performance in schizophrenia.

Background: Inappropriate arginine vasopressin (AVP) secretion has been reported in schizophrenic patients. However, there is lack of information on serum level of copeptin and its diagnostic performance in schizophrenia. This study therefore, evaluated serum copeptin and its diagnostic performance in schizophrenic patients.

Methods: Sixty subjects (30.02 ± 7.17 years) with schizophrenia (19 drug naïve [DNS] and 41 schizophrenics on treatment [SOT]) and 30 healthy individuals (33.62 ± 9.05 years) with no history of schizophrenia were enrolled into this study. Schizophrenia was diagnosed using the Tenth edition of the International Classification of Diseases and Related Health Problems (ICD-10). Estimation of serum copeptin, plasma electrolytes (potassium, sodium and chloride) and uric acid was done using ELISA, Ion-Selective electrode (ISE) and enzymatic method respectively.

Results: Copeptin was significantly higher while uric acid, potassium and sodium levels were significantly lower in patients with schizophrenia compared with controls. Similarly, copeptin was significantly higher while sodium, potassium and uric acid levels were significantly lower in DNS and SOT compared with controls. However, insignificant elevation in copeptin level and insignificant reduction in sodium, potassium, chloride and uric acid levels were observed in DNS compared with SOT. The Area under the curve (AUROC) for copeptin was 0.686 (P = 0.004).

Conclusion: There is elevated copeptin level in patients with schizophrenia and that copeptin levels might be a valuable tool in the diagnosis of schizophrenia.