5.2 Diagnostic criteria
Serotonin syndrome is a clinical diagnosis based primarily by evaluation
of the patient’s medical history (use of serotonergic drugs or illicit
substances, change in dose or addition of new drugs) and a physical
examination 2–4. No biomarkers have been identified
for serotonin syndrome, although certain nonspecific laboratory
abnormalities, such as leukocytosis, low bicarbonate level, elevated
creatinine level, and elevated transaminases, have been reported4.
Several diagnostic criteria have been suggested for the categorization
of serotonin syndrome. The most accurate are the Hunter Serotonin
Toxicity Criteria that have replaced the older Sternbach Criteria. The
Hunter Criteria have 84% sensitivity and 97% specificity for moderate
and severe serotonin syndrome when compared to the diagnostic gold
standard for serotonin syndrome: a diagnosis by a medical toxicologist.
Mild cases of serotonin syndrome are difficult to distinguish from
numerous other medical conditions and side effects, which is why the
Hunter Criteria cannot be used for this 3,8.
The Hunter Serotonin Toxicity Criteria appear in figure
13 below.