Autism and lactic acidosis.

Doctors wrote up four kids with autism who also had lactic acidosis. The paper is a short case series from 1985. No treatment was tested; the team just noted the double diagnosis.

All four children had high blood lactate, low muscle tone, and developmental delays. The authors suggest these kids might form a rare “metabolic” subgroup within autism.

Kang et al. (2014), LeBlanc et al. (2003), and Chandler et al. (2013) each counted GI complaints in larger ASD samples. They found chronic constipation or diarrhea in roughly one out of every two kids. Malouff et al. (1985) looks like an outlier because it points to lactic acidosis, not gut pain. The difference is method: the 1985 paper is a tiny case series hunting rare metabolic signs, while the later studies used surveys and clinics to capture common GI symptoms. Both lines tell the same story—look past behavior for hidden medical issues—but they screen for different body systems.

Barnhill et al. (2020) adds a twist: one preschooler with ASD and Fragile X felt better on a Specific Carbohydrate Diet. That single case hints that carb metabolism can matter for some kids, giving indirect support to the 1985 “metabolic subgroup” idea.

When a client looks weak, flushed, or extra lethargic, ask the pediatrician to check a lactate level—especially if standard GI screens are clear. Catching lactic acidosis early can spare pain and cut problem behavior that looks “autistic” but is actually metabolic.