Platelet size, number, and serotonin content in blood of autistic, childhood schizophrenic, and normal children.

Bachman et al. (1988) drew blood from three groups of children: kids with autism, kids with childhood schizophrenia, and typical kids.

They measured how big the platelets were and how much serotonin each platelet held.

The goal was to see if bigger platelets might hold more serotonin and explain why many autistic children have high blood serotonin.

Platelet size did not differ among the three groups.

Serotonin levels were also unrelated to platelet size.

In short, platelet volume is not the reason serotonin runs high in autism.

Thompson et al. (1986) had already shown that autistic children move serotonin into platelets faster, so the machinery works differently even if platelets are not bigger.

Northup et al. (1991) later found the highest serotonin in autistic children who also have an affected sibling, turning the neutral 1988 result into a possible family-risk marker.

Hranilovic et al. (2007) extended the work to adults and linked higher serotonin to poorer speech, showing the biomarker lasts beyond childhood.

Cohrs et al. (2017) added that the spike is mainly seen in pre-pubertal boys, explaining why a mixed child sample might miss smaller effects.

You can stop wondering if platelet size causes high serotonin in autism. When you order lab work, focus on serotonin level itself, not platelet volume. If the level is high, consider family history and language goals rather than general autism severity.