In the neonatal developmental stages, propionic acidemia, which is a medical issue defined as the lack of propionyl-CoA carboxylase, can cause impairment, mental disability, and numerous other issues. This is caused by an accumulation of propionyl-CoA because it cannot be converted to methylmalonyl-CoA. Newborns are tested for elevated propionylcarnitine. Further ways of diagnosing this disease include urine samples. Medications used help to reverse and prevent recurring symptoms include using supplements to decrease propionate production.