Disorders of amino acid metabolism symptoms include muscle weakness and other problems.
The human body uses amino acids to build proteins and other chemicals that are necessary for growth and development. When the body doesn’t use up these proteins and other chemicals quickly enough, the excess can build up in the blood and cause a disorder.
Several of these disorders can be diagnosed with medical tests. These tests are used to look for abnormalities in the way a person’s body uses the amino acids in their diet and other things they eat.
Genetic Disorders
Most of these disorders are caused by mutations in a gene that codes for an enzyme needed to process the amino acids. These errors are usually passed down through families and can affect anyone.
Phenylketonuria
People who have phenylketonuria (PKU) have a defect in an enzyme called phenylalanine hydroxylase. This enzyme is important for breaking down the amino acid phenylalanine into threonine and hydroxylamine. When the body doesn’t have enough of this enzyme, it can’t break down phenylalanine and threonine efficiently. This can lead to severe complications, including brain damage and death.
Amino Acid Deficiency
Some people can’t absorb some of the essential amino acids, such as arginine and methionine. This can cause them to become dehydrated and have trouble breathing or eating. It can also cause them to have a condition called kwashiorkor, which causes vomiting and diarrhea.
Other signs of an amino acid deficiency are low blood levels of protein and a high level of urea, an end product from protein breakdown. This can cause kidney failure or even death if it isn’t treated early.
Amino Acid Analysis, Plasma and Urine
This test looks at a person’s blood for different types of amino acids. The doctor takes a sample of the blood and checks it for the presence of 36 different types of amino acids. This test is often done in a lab.
Amniocentesis
This type of test can be done before a baby is born to check the baby’s amino acid levels. The test can be done before the baby is born by pricking the heel of the baby’s foot to get a blood sample.
Newborn Screening
This newborn screening test looks at the level of methionine and homocysteine in a child’s blood. This test is sometimes done before a child is born, so it can catch disorders that might not otherwise be detected.
Maple Syrup Urine Disease
This disorder is a rare inherited condition that causes the body to break down certain amino acids into substances in the blood and urine that can be harmful. This results in a characteristic “maple syrup” odor in the patient’s urine.
The treatment for this disorder is to avoid certain foods and take special formulas that contain the missing amino acids. These diets can improve the quality of life for the patient and their family. However, some patients will not respond to this treatment. They will still need to monitor their condition. They might need to take a drug called methylfolate or vitamin B12.
