Emergency Regimens for Inherited Metabolic Disorders (IMD)

Inherited metabolic disorders (IMD) encompass disorders across a myriad of metabolic pathways. Some of these pathways and disorders can be significantly affected in times of catabolism or metabolic stress (e.g. surgery, acute illness/infection, dehydration/volume depletion). This can result in life-threatening clinical and biochemical syndromes which can include:

- Hyper-ammonaemia

- Rhabdomyolysis

- Metabolic acidosis

IMD which result in these life-threatening clinical situations arising can sometimes be referred to as decompensating disorders. In all cases, patients with an IMD at risk of metabolic decomensation should have an emergency plan in place that summarises the key features of a decompensating episode, as well as the immediate management steps to take. This is because where patients present to a hospital A&E where their metabolic team is not present, or it is out of hours, clinical teams need an easy to follow plan that can be followed immediately.

Emergency plans are disorder specific but certain groups of disorders follow basic principles of treatment plans:

- Fatty Acid Oxidation Disorders (FAOx) - stop catabolism by giving glucose source (IV Dextrose), rehydrate to counteract the metabolic acidosis, consider escalation to intensive care if signs of acute rhabdomyolysis and monitoring of complications

- Urea Cycle disorders (UCDs) - IV ammonia scavengers, consider dialysis if encephalopathic of ammonia significantly high, stop catabolism

- Oragnic Acidaemias (OAs) - halt catabolism by giving IV Dextrose, consider ammonia levels and dietary protein intake

Reflective exercise

Review a couple of emergency regimens published by the BIMDG website and summarise some principles of management across a number of disorder groups.