A total of 1,104 articles examining serotonin (5-HT; 5-Hydroxytryptamine) measurements in autistic children have been analyzed. In 59% of these articles, elevated serotonin levels were identified in children with autism. In 25% of the articles that reported high serotonin levels, a correlation between elevated serotonin and speech disorders and behavioral problems observed in autism was mentioned.

So, is it possible to measure serotonin levels? Yes, serotonin levels can be measured. There are two methods for measurement:

1. Measurement of serotonin levels in the blood.
2. Measurement of serotonin metabolic product (5-HIAA; 5-Hydroxyindoleacetic Acid) in urine.

Which method would you recommend for measurement? Which measurement is healthier and more accurately reflects serotonin levels? Blood measurement of serotonin levels provides more accurate results. Urinary measurement of metabolic products may not fully reflect the actual serotonin amount. This is because some serotonin is converted into melatonin hormone after completing its functions in our body, while the remaining portion is converted into a metabolic product (5-HIAA) through an enzyme (MAO; Monoamine Oxidase) and excreted in urine. In summary, the final product measured in urine does not accurately reflect the total serotonin amount in our body, as some of it has already been converted to melatonin.

After measuring serotonin levels, the results should be accurately interpreted in conjunction with the case. This way, appropriate interventions can be applied for high values, ensuring they remain within normal ranges.