Methylsuccinic (Males Age 13 and Over)

Increased urinary levels of methylsuccinic acid (together with ethylmalonic acid) are the main biochemical measurable features in ethylmalonic encephalopathy, a rare metabolic disorder with an autosomal recessive mode of inheritance that is clinically characterized by neuromotor delay, hyperlactic acidemia, recurrent petechiae, orthostatic acrocyanosis, and chronic diarrhea. The underlying biochemical defect involves isoleucine catabolism. 

Other inborn errors:

Moreover, methylsuccinic acid is found to be associated with isovaleric acidemia, and medium-chain acyl-CoA dehydrogenase deficiency, which are also inborn errors of metabolism.

High Methylsuccinic levels may also be due to:

- carnitine deficiency, 
- fasting, 
- increased intake of the medium-chain triglycerides found in coconut oil, MCT oil, and some infant formulas. 

Regardless of cause, supplementation with L-carnitine or acetyl-L-carnitine (500-1000 mg per day) may be beneficial.

Methylsuccinic acid is a normal metabolite found in human fluids and is an intermediate metabolite in the breakdown of fatty acids.