Every newborn is screened for hormonal, metabolic and genetic disorders that are collectively termed as newborn screening tests. These tests are part of public health service in the United States. Most of the illness that is identified through these tests is rare, but an early diagnosis can help treat better. Lets have a look on how these tests are done and which diseases are diagnosed in these screening tests.
Last Updated: Oct 22, 2020 11:29 GMT
The screening tests may vary from state to state. There are certain national recommendations for newborn screening and the state decides on what tests need to be included. Approximately 4 million newborns in the United States are tested for congenital conditions (each year) through newborn screening tests and nearly 5000 babies are detected with severe disorders. Newborn screening can save babies from disability and premature death.
The following categories of tests are included in newborn screening.
1. Metabolic problems: Metabolism is the process of converting food into energy so that the body can use for day to day activities. There are enzymes (special proteins) that are responsible for this conversion process. When there is a defect in the enzymes, there can be problems in the metabolism. These disorders are termed “inborn errors of metabolism”. Metabolic disorders that are part of newborn screening include:
Phenylketonuria: This is a rare condition that affects 1 in 10,000 babies. In this disorder, there is an accumulation of an amino acid called phenylalanine in blood that results in brain damage. Early initiation of treatment like a special diet can help prevent disabilities and allow babies to lead a normal life.
The other common metabolic problems include methylmalonic acidemia, maple syrup urine disease (MSUD), tyrosinemia, citrullinemia and medium chain acyl CoA dehydrogenase (MCAD) deficiency
2. Hormone problems: Hormones are chemical messengers secreted by glands. There can be problems when the glands make too much or too low hormones. Congenital hypothyroidism and congenital adrenal hyperplasia are the two hormonal disorders screened in newborn screening.
Congenital hypothyroidism: This disorder is seen in 1 in 3,500 babies. There is a malfunction in the thyroid gland and there is too little thyroid hormone. The disorder can affect physical and mental development.
Congenital adrenal hyperplasia: This condition is seen in 1 in 15,000 babies. Babies born with this condition cannot make enough hormones called cortisol which helps control energy levels, sugar and blood pressure.
3. Hemoglobin problems: Hemoglobin is a vital protein present in red blood cells which carries oxygen throughout the body. Some of the hemoglobin disorders that are diagnosed in newborn screening are
· Sickle cell disease: The disease causes severe anemia and occurs in 1 in 500 African Americans and 1 in 36,000 Hispanic American births. Early diagnosis can help prevent infections, blood clots and stroke
Other hemoglobin diseases identified through newborn screening include hemoglobin SC disease and Beta Thalassemia.
4. Lysosomal storage disorders: Babies born with these disorders cannot break down some complex sugars. Examples of these disorders include mucopolysaccharidosis type 1and Pompe disease (glycogen storage disease type II)
Some of the other problems that are identified in newborn screening include:
· Galactosemia: This condition is seen in 1 in 40,000 babies and there is an accumulation of galactose in blood. Treatment involves diet with galactose free milk. Untreated galactosemia can be life threatening.
· Cystic fibrosis: 1 in 2,500 babies have cystic fibrosis. In this condition the mucus produced by the lungs and intestines is thicker than normal. Babies with this condition may have infection in the lungs and have difficulties in digesting the food.
· Biotinidase deficiency
· Severe combined immunodeficiency (SCID)
· X-linked adrenoleukodystrophy
· Spinal muscle atrophy (SMA)
5. Hearing loss: To test for hearing loss, a healthcare provider places a tiny earpiece or microphone in the infant's ear. Another method involves placing electrodes on the baby's head while the baby is quiet or asleep.
6. Critical Congenital Heart Disease (CCHD) Screen (also called “Pulse oximetry”): A soft sensor is placed on the baby’s skin that is attached to an oximeter. The oximeter measures the levels of oxygen in the baby’s hand and foot.How is the test done?
Before the sample is collected, a verbal or written agreement is collected from parents of the child. A small amount of blood sample is collected from the baby’s heel on a special filter paper. The filter paper is allowed to dry and will be sent to the laboratory for testing.
The sample is usually collected before the baby leaves the hospital, at one to two days of age. In most cases, a second test at one to two weeks of age is also done in some states.Results
The results of hearing loss and congenital heart disease are disclosed to the parents immediately after the test is done. The results of blood tests for hormonal, genetic and metabolic disorders are reported in another 3 to 4 days interval. The parents are contacted if the test results are positive. If a positive test result is identified, some additional tests are done to confirm a diagnosis. Treatment will be initiated as early as possible and the babies will be referred to the respective speciality departments.