Story 04 · Genes and medicine
A few drops of blood from a baby's heel
Since the 1960s, a few drops of blood from a newborn's heel have been used to find rare conditions early, when treatment can prevent serious harm, though a screening result always needs confirming.
- Newborn blood spot screening
- United States, and now worldwide
- 1963
- 3 min read
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Before you readWhat would you do?
A new parent gets a call saying their baby's heel-prick screening result needs a repeat test. They ask a chatbot, which lists frightening diseases. What should they do?
Pick an answer now. The file tells you whether you were right.
01The file in one minute
1The test
In the early 1960s Robert Guthrie developed a PKU test using a few drops of a baby's blood dried on paper.
2Why it matters
Conditions like PKU and congenital hypothyroidism cause far less harm when treatment starts early.
3The limit
A screening result is not a diagnosis. A positive screen needs follow-up tests, and many are false alarms.
4The lesson for AI
AI flags work like screening: a reason to look closer, not a final answer.
02Timeline
Early 1960s
Robert Guthrie develops a blood spot test for PKU.
1968
A WHO report sets out principles for when screening makes sense.
Later decades
Countries add more conditions to newborn screening.
Today
Newborn screening is offered in many countries, including Vietnam.
03The story
In the early 1960s the American doctor Robert Guthrie developed a simple test for phenylketonuria, or PKU, using a few drops of a baby's blood dried on filter paper. Babies with PKU cannot process a substance found in many foods. Without treatment it can cause serious intellectual disability. With a special diet started early, children can grow up healthy.
The dried blood spot method spread worldwide. Today, many countries test newborns for a list of conditions, which differs by country. Common ones include PKU, congenital hypothyroidism, sickle cell disease and certain metabolic disorders. In Vietnam, many hospitals offer newborn screening, often including congenital hypothyroidism and G6PD deficiency.
The sample is usually taken a few days after birth. Most results are normal. If a result is not, the family is called back for more tests, because a screening test is designed to catch possible cases, and some of them turn out to be fine.
04What the science says
Screening works best for conditions that are serious, can be found with a simple test before symptoms appear, and can be treated better when caught early. Those rules come from public health thinking that WHO helped set out in the 1960s.
A screening test is not a diagnosis. Because the conditions are rare, a positive screen is often a false alarm, and only follow-up tests can confirm it. That is why calm, quick follow-up matters.
The AI angle: many AI tools work like screening tests. They flag cases for a closer look, and some flags will be wrong. A flag from an AI is a reason to check, not a final answer.
The idea behind this caseLesson: Check what AI tells you →
05What to take from it
- Ask your hospital which newborn screening tests your baby will have, and when results come.
- If you are called back after a screening test, go to the follow-up promptly. Many call-backs turn out to be fine.
- Treat any screening result, from a lab or an AI tool, as a reason to look closer, not a final verdict.
- Talk to your baby's doctor about any result you do not understand, and do not rely on internet searches or chatbots for the meaning.
07 — Sources
- Newborn blood spot test · NHS · 2024
- Newborn screening · Wikipedia · 2024