There are certain diseases whose diagnosis improves if they are detected early. On the other hand, if they are allowed to pass, the symptoms may appear when a treatment is not started and their prognosis is but. The so-called “heel test” are tests to detect and be able to treat certain metabolic diseases early .
Neonatal screening, neonatal screening or heel test is a blood test that seeks a very early diagnosis of diseases that have a very good prognosis if detected early, such as hypothyroidism, phenylketonuria, cystic fibrosis … If these diseases were diagnosed late, we could talk of serious complications, even irreversible in certain cases.
That is why the heel test is so important in newborns, all of them are performed in the hospital environment and in this way the test becomes a very important preventive puncture.
Diseases detected by the heel test
As we have commented, neonatal screening is a metabolic test , and within all metabolic diseases, those that are more frequent and that have a treatment that considerably improve the prognosis of the disease if applied early are sought.
These metabolic diseases are characterized by a malfunction of the body’s internal chemistry (metabolism), resulting in an increase or a lack of certain substances. The consequences would be a malfunction of various organs (depending on the type of disease it can be the heart, liver, lungs …), alterations in the development of the brain and mental retardation and growth and development disorders or anemia. Most of these diseases have a genetic basis and are inherited, even if they are not suffered by the parents.
However, depending on the country and even the autonomous community and the different protocols, the diseases that are sought with the test are not the same . In Spain, the detection of phenylketonuria and congenital hypothyroidism is included in all metabolic screening programs. Cystic fibrosis of the pancreas and congenital adrenal hyperplasia are also included in many communities.
In three communities there is a screening program for congenital hemoglobinopathies, which are diseases that are born at birth and cause anemia. Some communities have analysis technologies such as mass spectrometry, which allow the detection of many more metabolic diseases.
Hyperphenylalaninemias, galactosemia, biotinidase deficiency, maple syrup disease, homocystinuria, medium chain fatty acid beta-oxidation defects, and tyrosinemia are other metabolic diseases that are detected in the heel test in different European countries.
When and how to do the heel test
The heel test is performed by puncturing the baby’s heel with a lancet , a surgical instrument to make small incisions. It is a capillary blood sample, that is, taken superficially, it is not a deep incision. The heel is slightly compressed by the puncture area and blood is allowed to drip, impregnating a special absorbent paper that will be sent to the laboratory for analysis.
The test is uncomfortable and may hurt the baby. To alleviate this pain, nothing better than “tetanalgesia”, breastfeeding while the puncture is being performed, being in contact with the baby. If this is not possible, the AEP recommends administering a sugar water solution and always contacting the mother, talking to her, caressing her.
Depending on the different programs, one or two tests are usually done. You can ask your hospital center or midwife what the exact procedure is in your case and what diseases are detected in your community or region.
The Commission on Congenital Metabolic Errors of the Society for Clinical Biochemistry and Molecular Pathology recommends that, as a general rule, the extraction of blood from the heel should be carried out as soon as possible after 48 hours of life. It recommends two strategies according to the different geographical and infrastructure conditions of each autonomous community in order to guarantee 100% coverage of newborns in their area:
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Single extraction . From 48 hours of life of the newborn, with established protein feeding, obtaining a single sample for the detection of hypothyroidism, phenylketonuria and congenital adrenal hyperplasia.
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Double extraction . The first extraction from 48 hours of life, before hospital discharge, for the detection of hypothyroidism and congenital adrenal hyperplasia and the second from the fifth day of life for the detection of phenylketonuria.
In some countries a test is carried out between 48 hours and 72 hours of the child. The optimal moment for obtaining the sample is controversial and therefore we observe these differences.
Together with the collection of the impregnated blood on paper, the data of the family and the baby are collected in a file that, later, will be used to send the results obtained and contact the parents if necessary.
If the heel test is positive , it will be repeated to verify that there is no error and if a metabolic disease is finally confirmed, treatment will be started and the parents will be guided by genetic counseling as to whether successive children may suffer from the same problem .
In short, the heel test is a test that is performed on the newborn and that can reduce complications and save the life of the baby . All newborns have the right to this free study, which is carried out in all hospitals and, although we are sorry that they have to prick him, so tiny, it is highly recommended to prevent.
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More information | AEPED
In Babies and more | The heel test a preventive prick, The heel test in newborns
