The value of serum uric acid levels to differentiate causes of transient loss of consciousness

Background: Generalized tonic-clonic seizures (GTCS), syncope, and psychogenic nonepileptic seizures (PNES) are common emergent neurological conditions that cause transient disturbances of consciousness; however, it is sometimes difficult to distinguish them.

Objective: This study aimed to explore the value of serum uric acid levels in differentiating among GTCS, syncope, and PNES by analyzing serum uric acid levels in patients with GTCS, syncope, and PNES.

Methods: A total of 391 patients were retrospectively analyzed. Venous blood was drawn from the patients within 20 min of their arrival to the emergency department; serum uric acid levels were measured using the uricase method.

Results: Serum uric acid levels and the percentage of patients with elevated uric acid (elevation percentage) were significantly higher in the group with GTCS (n = 179) than in the groups with syncope (n = 156) (p < 0.001) and PNES (n = 56) (p < 0.001). The result remained the same when the serum uric acid level of male or female patients in the group with GTCS were compared separately with that in the other two groups (all p < 0.001). In the group with GTCS, both the serum uric acid level (p < 0.001) and elevation percentage (p < 0.05) were significantly higher in males than in females. The receiver operating characteristics (ROC) analysis in male patients yielded a serum uric acid value of 428.50 μmol/L with a sensitivity of 0.78 and a specificity of 0.99 as the optimal cutoff value to distinguish GTCS from other events. In female patients, a cutoff value of 338.00 μmol/L had a sensitivity of 0.69 and a specificity of 0.91 to distinguish GTCS from other events. For the group with GTCS, the period of time between the onset of seizure and serum uric acid levels dropping to normal were analyzed in 40 patients. The duration was 44.56 ± 11.46 h for males (n = 23) and 40.37 ± 9.78 h for females (n = 17) with no significant difference (p = 0.325).

Conclusion: Serum uric acid levels provided certain clinical value for the differentiation of GTCS, syncope, and PNES; however, this requires verification in prospective studies with larger sample sizes.