whyis ketosis seen in organic acidemias?

[gulsen]

Maybe the questoin is simple but i couldn't find an answer in clinical textbooks. organic acidemias are related with amino acid catabolism and there's a block in catabolism pathway. so if the amino acids can't degrade to their end products such as pyruvate or acetyl coA, where the ketone bodies seen in these disorders come from?

[Elite Engineer]

Ketoacidosis is the result of the inability to take up glucose in the bloodstream, resulting in breakdown of lipids anc AA's making ketone bodies.

 

Organic acidmeia is a metablic disorder cause by defective genes that results in the improper breakdown of AA's. The acid's come from a defective enzyme(s).

 

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In ketoacidosis, the typical products are acetone, beta-hydroxybutrate, and acetoacetatic acid.

 

In organic acidmemia, the irregular acid products are methylmalonic acidemia, propionic acidemia, and isovaleric acidemia. These are generally not seen in ketoacidosis.

 

 

 

Ketoacidosis products aren't seen in OA. Keotacidosis and OA do not share the same mechanisms.

 

~EE

[gulsen]

thank you for the answer but ketosis is seen in some organic acidemias such as propionic acidemia. while i was looking for a reference for this information, luckily i found the answer.

organic acids can inhibit gluconeogenesis therefore fatty acid oxidation increases to meet body's energy requirement. Also organic acidemias cause hyperammonemia by inhibiting urea cycle. But thanks again, i searched a lot, but couldn't find the answer till now...

 

reference: https://books.google.com.tr/books?id=a7CqcE1ZrFkC&pg=RA3-PA987&dq=organic+acidemia+ketosis&hl=tr&sa=X&redir_esc=y#v=onepage&q=organic%20acidemia%20ketosis&f=false

[BabcockHall]

Your reference also notes that some organic acidemias are associated with hypoketotic hyperglycemia. I am not surprised that difference metabolic defects show a variety of outputs.

[gulsen]

yes you're right some of them are associated with hypoketotic hypoglycemia which was more logical for these pathway blocks. But most of them make ketosis.

[Xalatan]

I think the answer you are looking for is, in starvation, gluconeogenesis is in full steam and there is a relative lack in oxaloacetate. This may be the catabolic block you are referring to, since the tca cannot turnover. In this case the acetylcoa from beta oxidation cannot enter the krebs cycle, so it is converted to hmg coa for ketogenesis. Since keto acids are organic acids insulin deficiency will lead to organic acidaemia and will show up on your anion gap.