Stable isotope studies in propionic and methylmalonic acidaemia.

Stable isotope techniques have been used to measure propionate production and disposal in patients with propionic and methylmalonic acidaemia. There are wide variations between individual patients but aminoacid catabolism accounts for approximately 50% of propionate production, bacterial activity in the gut 25% and catabolism of odd chain fatty acids 25%. Oxidation of propionate is an important route of disposal. These studies have helped to improve the management of inborn errors of propionate metabolism.