What are metabolic disorders?

Metabolic disorders are different conditions that affect the body’s metabolism and ability to break down food. Metabolic disorders are commonly inherited from family where they have inherited a defective gene which results in enzyme deficiency.

These are called inherited metabolic disorders. There are hundreds of different metabolic disorders and the symptoms, prognosis and treatment can differ a lot.

The metabolism is the complex set of processes and chemical reactions that allows your body to create energy. Enzymes and certain chemicals are needed for this and if these enzymes or chemicals are not available, a metabolic disorder results.

There are different categories of metabolic disorders and include:

• Disorders where a certain enzyme or chemical builds up because it cannot be broken down.
• Disorders that have too little of a certain enzyme or chemical.
• Disorders that are missing certain enzymes or chemicals.

Phenylketonuria (PKU) is one inherited metabolic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase. This can result in learning and physical disabilities if not treated.

Other inherited metabolic disorders include:

• Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)
• Maple syrup urine disease (MSUD)
• Glycogen storage disease (GSD)
• Galactosaemia
• Mitochondrial disorders

Prognosis of metabolic disorders:

Depending on the type of metabolic disorder and how well it is managed, children and adults can become quite ill and need hospitalisation with metabolic disorders. Some that are detected at birth, if treated can be managed well.

Symptoms of metabolic disorders:

The symptoms of metabolic disorders vary depending on the type of disorder and can either be chronic or come on suddenly. In inherited metabolic disorders, symptoms can present soon after birth, but some only won’t be obvious for years. Symptoms can include:

• Fatigue
• Nausea
• Weight loss
• Poor appetite
• Abdominal pain
• Seizures
• Jaundice
• Developmental delays
• Coma

Medical tests to diagnose metabolic disorders:

All babies are screened for certain inherited metabolic disorders. If a baby is suspected of having a metabolic disorder after birth, blood tests will be run to determine this.

If a metabolic disorder is not detected at birth, sometimes symptoms won’t appear for a while, which when they do will require blood tests and DNA analysis to diagnose. Specialist centres and teams are able to do this.

What are the causes of metabolic disorders?

Most metabolic disorders are caused by the fact that a single enzyme is not made by the body or does not function properly. The code required to create that specific enzyme is contained on a pair of genes, which if defective can result in a metabolic disorder. However, only children that inherit two copies of a defective gene from their parents will develop a metabolic disorder.

Can metabolic disorders be prevented?

Inherited metabolic disorders cannot be prevented, however, if managed and treated early on, the prognosis is often better.

Treatments for metabolic disorders:

There are no cures available for inherited metabolic disorders, however, treatment focuses on overcoming the problems with metabolism. However, treatments will vary depending on the type of metabolic disorder.

Treatment may involve a special diet that eliminates certain nutrients, taking enzyme replacements or detoxifying the blood of dangerous chemical that have built up as a result of impaired metabolism.

Which type of specialist treats metabolic disorders?

An endocrinologist would treat metabolic disorders.