No one likes the idea of their precious new baby getting pricked in the heel for testing. But that test – the Newborn Metabolic Screening – is an important one that can ensure you baby can reach their full potential and spot the early signs of problems.
To understand metabolic disease, we first need to talk about how we normally digest food.
The food we eat is first broken down into small pieces by chewing. And then broken down even more by chemicals and enzymes in our digestive system. It gets broken down into large molecules. And then those large molecules are broken down into smaller molecules that your cells can actually make use of to give you energy, build and repair cells, etc.
With a metabolic disease, something goes wrong in the part of digestion that involves chemicals and enzymes to break the larger molecules into smaller ones the body’s cells can use. So instead of having something useful, the body has two problems:
- Not getting the nutrients needed into the cells
- Large unusable molecules building up in the bloodstream that can’t be used up.
These problems can cause a whole bunch of larger issues. Everything from sore muscles, to brain damage, or even death!
Some of the most common metabolic diseases include:
- PKU – Caused when the body can’t break down phenylalanine, a component of protein. The first metabolic disease there was a screening for, and sometimes this screening is called the “PKU test” even though it screens for much more these days. About 1/12,000 babies are diagnosed each year.
- Galactosemia – Caused by an inability to break down the sugars in breast milk or formula, about 55,000 babies are diagnosed each year.
- Maple syrup urine disease – Yup, makes the baby’s pee smell like maple syrup! This is caused when babies can’t break down three different components of protein, and happens in about 1/185,000 babies.
Ideally, you want to know if this is happening before it gets to the point that you have irreversible damage. Enter newborn metabolic screening!
The newborn metabolic screening is usually done a day or two after birth. It’s not done right at birth because the baby needs to have been eating before we can know how well they are able to digest food. A nurse, midwife or doctor can do the blood draw. In most areas, the screening is done by taking a small amount of blood from the baby’s heel and putting the blood in little circles on an absorbent card that is then sent to the lab for testing. The vast majority of the time, all is well and parents don’t need to worry about it again. If the test shows a potential issue, the baby will have more blood work done to definiteively say if there is a problem.
Generally the test is repeated at the first office visit with the baby’s care provider, just in case they had not eaten enough before the first screening test. This most often happens around ten days to two weeks after birth.
There are a few other screening tests done with the same sample, things that are not metabolic diseases but can be done at the same time, like testing for thyroid function or looking for toxoplasmosis. The specific tests done with the sample can vary widely based on where you live, but most of the things they are screening for with this sample are metabolic diseases.
The odds of your baby having an issue are quite low, but since early identification and treatment are key to avoiding permanent issues, metabolic testing is worth the heel prick.