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There are many diseases that depend on early diagnosis for successful treatment. Due to this, there are many types of tests or examinations whose objective is to detect diseases that may be congenital in time and that, therefore, are performed on newborns.

Such is the case of the well-known heel test, a test that is carried out on babies who have just arrived in the world and that allows the detection of some hereditary metabolic diseases. This test is not mandatory for all neonates, but it does help to detect some diseases early before they show symptoms.

What is the heel test?

The heel test is the name by which a neonatal test that is performed after the first 48 hours of birth is known. This test is called neonatal screening and is characterized by its ability to detect some inherited metabolic diseases early.

It consists of taking blood samples from the baby to look for any possible inherited metabolic disease . The reason why it is known as a heel test is because the blood is obtained by pricking the baby’s heel, and then passing it to a special absorbent paper that is previously prepared for neonatal screening.

This test is not mandatory in all countries and is usually performed in maternity wards, clinics or hospitals. In those cases where this test is not mandatory, it is advisable to ask for it, since if a disease is detected, it is possible to act in time.

How is the heel test performed?

The heel test is a two-stage blood test . The first stage takes place between the 2nd and 5th day after the baby is born. During this stage, a puncture is carried out in the baby’s heel to extract some drops of blood, which are subsequently dropped on a special filter paper. Once this is done, it is necessary to take it to a neonatal laboratory where the blood will be tested.

The amount of blood tests done will depend on the type of heel test done. Since, depending on the place where it is carried out, some diseases or others may be analyzed. In some cases, an extended heel test can be performed, which is a more comprehensive version of the heel test and allows the detection of other diseases that common neonatal screening does not detect. The average duration of these analyzes is approximately 3 to 5 days ; depending on the place where they take place.

Once the corresponding analyzes are completed, the parents are informed of the results. If it is negative and no hereditary metabolic disease has been seen, it is most likely that only an email will be sent with the test results. However, if the test is positive and the baby has such a disease, it is likely that they will call the family or medical center where the baby is directly to carry out the second stage of the test.

The second stage consists of a verification test. That is, if the first blood sample tests positive for any of the diseases, a second test is performed to confirm that it is not a false positive . If the second test again turns out to be positive, doctors will proceed to instruct the baby’s parents on the treatment they should use to control the effects of the disease that is present.

Despite being common for a second neonatal screening to be performed, there are cases in which this second verification test is not performed , either because no abnormality was observed with the first tests or because the medical center where they were performed is not in the habit. to do so.

Double extraction

Another method by which this test is performed is through a double extraction. In this case, two individual tests are performed to detect different diseases. The first blood draw is done 48 hours after the first. Its objective is to detect metabolic diseases such as hypothyroidism and congenital adrenal dysplasia.

On the other hand, the second blood draw is carried out after 5 days of birth. Through it, it seeks to detect diseases such as phenylketonuria . Because in this case the test is done in two parts, the results may take time to come out. However, they are a bit more specific and reliable, although it will also depend on the center where the analyzes are performed.

Heel test results

The results of the heel test are direct, determining only if the tests are positive or negative for each of the diseases studied. When neonatal screening tests positive for any of the diseases, it means that these diseases are present and therefore there is a need to act immediately and begin the necessary treatments for the detected diseases. In the case of negative, it means that the diseases are not present in the baby.

If for some reason, the results obtained during the heel test seem strange, or it is suspected that something went wrong during the test, the test will be repeated, giving more importance to those cases in which the result is positive.

What factors can alter the results of neonatal screening?

Although it is a simple test to perform, there are factors that can alter the final result, so care must be taken when performing it to ensure the reliability of neonatal screening. Among the most common factors that affect the results of this test we find:

  • Bad extraction : If a bad extraction is carried out at the time of obtaining the blood samples, contaminated samples can be obtained, which significantly alters the results.
  • Contact of the baby with its environment : Generally, during the first days of life, the baby is usually kept in controlled environments or in incubators. However, there may be cases in which the baby has direct contact with objects and people. If this contact is made prior to obtaining the sample, there is a probability that the results will be altered.
  • Low amount of sample : Just as a poor extraction influences, so does a scarcity of the sample. Depending on the number of diseases that are searched for during the test, more or less blood will be needed. If the sample is not sufficient, the results will not be very reliable or, even, the neonatal screening could not be completed.
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There are also other factors such as the misuse of the analysis equipment or the use of a paper other than the special paper used for this test. In this case, the problem lies with those responsible for carrying out the analysis.

What diseases does the heel test detect?

Depending on the site where this test is performed, more or less diseases can be detected. However, there are some that are common and are usually analyzed in all health centers where neonatal screening is performed. These diseases are:

Congenital hypothyroidism

A metabolic disease in which the thyroid gland does not produce enough thyroid hormones. In the long term, this disease can have serious consequences for the development of babies, especially during the first stages of growth, where these hormones play fundamental roles in musculoskeletal development.


Phenylketonuria is a disease that prevents the body from correctly processing phenylalanine , an essential amino acid that plays an important role in proper neuronal function. This disease can represent a great risk for the baby if it is not treated in time, having consequences that range from depression to sleep disturbances or even other serious psychological disorders such as bipolar disorder .

These two previous ones are, at least in Spain, the main diseases that are detected during the heel test and, no matter in which part of the country you are located, the test will always be carried out to detect these diseases. However, this does not mean that they are the only ones, since, as we mentioned before, in general the number of diseases that are detected will depend on the site where the test is performed.

Other diseases that are detected in neonatal screening

What you will see next are the possible diseases that can be detected through neonatal screening. We recommend that you always ask your doctor what are the diseases that are detected during the test, in this way you will have more accurate information.


Hemoglobinopathies refer to all those diseases that directly affect the blood, such as sickle cell anemia. The treatment of these diseases plays an important role in the health of babies, which is why the existence of these diseases is usually looked for in most of the heel tests that are performed.

Cystic fibrosis

A serious disease that if not treated in time can be fatal. This disease is characterized by the accumulation of mucous substances, usually very dark and sticky, in the digestive and respiratory channels, mainly in the lungs. There may also be the presence of these snotty substances in other parts of the body.

Adrenal Hyperplasia

This is another metabolic disease that can be detected through the heel test. Adrenal Hyperplasia causes a deficit in the production of hormones by the adrenal glands. This causes poor production of metabolic hormones such as cortisol. If not treated in time, this disease can cause irreversible damage to children, especially during their growth stage.

Biotinidase deficiency

This is another serious condition that can be detected through the heel test. This condition is that the body is not able to process biotinidase, a vitamin that intervenes in the body’s nervous processes. By not being able to process this vitamin, babies can present serious nervous problems, such as seizures or even psychomotor failures.


A metabolic disease in which the body is unable to process glucose from breast milk. This is a serious point especially during the first moments of the baby’s life, since it is during this stage where breast milk plays an important role during its development.

These are only a small part of the diseases that can be detected through neonatal screening. Most of these are metabolic or blood diseases. Some of them may be more serious than others. We remind you that not all health centers perform an extended test and that, in general, only about 4 or 5 diseases are detected per test, with congenital hypothyroidism and phenylketonuria being the most common in all countries of the world. world.

Heel test in babies

As you have seen, the heel test is an early detection test for a large number of congenital diseases that have a very good prognosis as long as they are treated in time. This test is very important for babies, so it is recommended to always do it during their first days of life. Even so, if the medical center where you are born does not perform this practice, it is best to find another place where you can perform neonatal screening.

Surely at this moment you are wondering if this test presents any risk to the baby, or if it hurts him in any way. Do not worry, because it is a totally safe test in which the newborn does not suffer any type of severe damage. At most, you will feel a little pain in the area where the puncture is done, although this is temporary and there are ways to distract your baby to avoid pain.

In most cases, everything ends very quickly and the only thing the baby feels is a slight discomfort in the heel. Remember that babies don’t even crawl at that age, so heel contact with solid surfaces is almost non-existent. This means that there will be almost no pain for the first few hours after taking the blood sample.

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Hello Readers, I am Nikki Bella a Psychology student. I have always been concerned about human behavior and the mental processes that lead us to act and think the way we do. My collaboration as an editor in the psychology area of ​​Well Being Pole has allowed me to investigate further and expand my knowledge in the field of mental health; I have also acquired great knowledge about physical health and well-being, two fundamental bases that are directly related and are part of all mental health.

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