What are metabolic disorders?
Metabolism is the breaking down of food to its simpler components: proteins, carbohydrates (or sugars), and fats. Metabolic disorders occur when these normal processes become disrupted. Disorders in metabolism can be inherited, in which case they are also known as inborn errors of metabolism, or they may be acquired during your lifetime. Many metabolic disorders exist, and they are common in the United States. For, instance, diabetes is metabolic disease that affects approximately 26 million Americans (Source: CDC).
Phenylketonuria is an example of an inherited metabolic disorder characterized by an inability to break down one of the building blocks of protein, the amino acid phenylalanine. Type I diabetes, a disease in which the pancreas does not create enough insulin to maintain balanced blood sugar levels, is a metabolic disorder of sugar metabolism. An example of a metabolic disorder affecting fat metabolism is Gaucher’s disease, which is characterized by a lack of the of the enzyme glucocerebrosidase. Metabolic disorders can also be complications of severe diseases or conditions, including liver or respiratory failure, cancer, chronic obstructive pulmonary disease (COPD, includes emphysema and chronic bronchitis), and HIV/AIDS.
Enormous advances have been made in the recognition and treatment of metabolic disorders. Sometimes there are highly complex pathways that result in a metabolic disorder. At other times, one miniscule error in an individual’s DNA is solely responsible. These discoveries have permitted scientists to develop extraordinary treatments for affected individuals, and the pace of discovery continues to accelerate.
Symptoms of metabolic disorders will vary among individuals and by the type of disorder. Some metabolic disorders result in mild symptoms that can be managed with medication and lifestyle changes, while others can cause severe and life-threatening symptoms, such as breathing problems, seizure, and organ failure. Some inherited metabolic disorders can require long-term nutritional supplementation and treatment, while metabolic disorders that arise as a result of another disease or condition often resolve once the underlying condition is treated.
Seek immediate medical care (call 911) for serious symptoms, such as severe difficulty breathing; bluish coloration of the lips or fingernails; seizure; and change in level of consciousness or alertness, such as passing out or unresponsiveness.
Seek prompt medical care if you are being treated for metabolic disorders but mild symptoms recur or are persistent.
What are the symptoms of metabolic disorders?
Metabolic disorders cause disturbances in the normal chemical processes in the body and will result in different symptoms, depending on the particular disorder. The symptoms can vary in intensity among individuals.
Symptoms of inherited metabolic disorders
Symptoms of metabolic disorders that run in families include:
- Body fluids that have a maple smell
- Bone abnormalities such as osteoporosis (thinning and weakening of the bones)
- Difficulty with memory, thinking, talking, comprehension, writing or reading
- Enlarged liver, heart, kidney or spleen
- Failure to thrive in infants and children
- Frequent infections
- Hypoglycemia (low blood sugar)
- Loss of vision or changes in vision
- Muscle twitching, spasms or seizures
- Muscle weakness
Symptoms of acquired metabolic disorders
Symptoms of metabolic disorders that you can acquire during your lifetime include:
- Chronic or persistent diarrhea
- Irritability and mood changes
- Muscle cramping
- Nausea with or without vomiting
- Rapid breathing (tachypnea) or shortness of breath
Serious symptoms that might indicate a life-threatening condition
In some cases, metabolic disorders can be life threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:
Bluish coloration of the lips or fingernails
Respiratory or breathing problems, such as shortness of breath, difficulty breathing, labored breathing, wheezing, not breathing, choking
What causes metabolic disorders?
Metabolic disorders develop when normal metabolic processes are disturbed. Normally, food is broken down by the body into simpler components (proteins, fats and sugars) in a highly regulated manner. Metabolic disorders are defined by a breakdown in any one of the steps of this complex process. Disorders in metabolism can be inherited, in which case they are known as inborn errors of metabolism, or they may be acquired. They may also occur as complications of other serious diseases, such as liver or respiratory failure, cancer, end-stage chronic obstructive pulmonary disease (COPD, includes emphysema and chronic bronchitis), and HIV/AIDS.
Inherited causes of metabolic disorders
There are numerous examples of inherited metabolic disorders, which can be classified based on the type of food-related building block that they affect, including amino acids (the building block for proteins), carbohydrates, and fatty acids (the building block for fats). Inherited causes of metabolic disorders include:
Amino acid disorders; examples include Tay-Sachs disease, phenylketonuria, tyrosinemia, maple syrup urine disease, and homocystinuria
Carbohydrate disorders; examples include diabetes insipidus, hereditary fructose intolerance, galactosemia, pyruvate metabolism disorders, von Gierke’s disease, McArdle disease, Pompe’s disease, and Forbes’ disease
Fatty acid oxidation defects; examples include Gaucher’s disease, Niemann-Pick disease, Fabry’s disease, and medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency
Other causes of metabolic disorders
Metabolic disorders can be due to other factors, such as a combination of inherited and environmental factors. Other examples of conditions that can cause metabolic disorders include:
Diabetes (chronic disease that affects your body’s ability to use sugar for energy)
Ingestion of poison or toxins, including excessive aspirin, bicarbonate, alkali, ethylene glycol, or methanol
Sepsis (life-threatening bacterial blood infection)
A number of factors increase the risk of developing metabolic disorders. Not all people with risk factors will get metabolic disorders. Risk factors for metabolic disorders include:
How are metabolic disorders treated?
Treatment for metabolic disorders begins with seeking medical care from your health care provider. The treatment approach for metabolic disorders depends on the specific disorder. Inborn errors of metabolism (inherited metabolic disorders) are often treated with nutritional counseling and support, periodic assessment, physical therapy, and other supportive care options. Acquired metabolic disorder treatment will include normalizing the metabolic balance by both reversing the cause and administering medications.
Treatment options for inherited metabolic disorders
Multiple treatment options are available for inherited metabolic disorders. Examples include:
- Bone marrow transplantation
- Enzyme replacement therapy in selected patients
- Gene therapy in selected patients
- Medications to reduce symptoms, such as pain or low blood sugar
- Mineral supplementation
- Nutritional counseling
- Physical therapy
- Surgery to relieve pain or symptoms
- Vitamin supplementation
Complications of untreated metabolic disorders can be serious, even life threatening in some cases. You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of metabolic disorders include:
- Organ failure or dysfunction
- Seizures and tremors
- Unconsciousness and coma