Children's Health: What Blood Tests Can Tell You

Children are not small adults, and a blood test for a child answers a narrower set of questions than an adult panel does. The questions worth asking are about growth, nutrition and a handful of conditions that are common, treatable, and easy to miss because their early symptoms look like ordinary childhood. Iron deficiency is the clearest example.

School lunches are skipped or eaten selectively, fussy eating is common, and adolescent girls lose iron every month once periods begin. Low iron affects attention, memory and mood well before it becomes anaemia, and a child who is irritable, struggling to concentrate in class or unusually tired is often assumed to be tired, distracted or difficult rather than short of iron.

Parents who contact us often have a feeling that something is not right, even though their child is not ill. Vitamin D deficiency is close to universal in Swedish children through the darker months. Coeliac disease affects roughly one to two percent of Swedish children and frequently presents as poor growth, stomach complaints or low energy rather than anything dramatic.

None of this is a reason to test every child routinely. It is a reason to test when something is not right and you want an objective answer rather than a guess.

What We Measure and Why

Iron status

Full iron studies are the core of a children's panel, and they mean four markers, not one. Ferritin measures stored iron, but it is an acute-phase reactant that rises during any infection, so a child who has recently had a cold can show a normal ferritin with empty stores. Serum iron, transferrin and transferrin saturation together reveal what ferritin alone can hide.

A complete blood count shows whether iron deficiency has progressed to anaemia and gives red cell size, which is often the first thing to change.

Vitamin D, B12 and folate

Vitamin D matters in Sweden more than almost anywhere, and it affects bone development during the years when bone is actually being built. Vitamin B12 and folate support growth, red cell production and neurological development; homocysteine rises when either is functionally low, so it acts as a check that the levels being reported are actually sufficient.

The thyroid

Thyroid function, through TSH and free T4, is worth knowing because thyroid problems in children affect growth and school performance and are easy to attribute to other things.

Coeliac disease

Coeliac screening uses transglutaminase antibodies (tTG-IgA), the standard first-line test.

Other markers

Calcium and zinc cover bone and immune function, and liver markers with creatinine give a baseline of organ function. Inflammation is measured with high-sensitivity CRP.

Children's Health Panel →Iron & nutrient tests →

When Testing a Child Is Worth It

  • Tiredness that does not improve with a normal amount of sleep
  • Difficulty concentrating at school, or a teacher raising concerns
  • Irritability, low mood or anxiety without an obvious cause
  • Poor appetite, restricted eating, or a vegetarian or vegan diet
  • Growth that has slowed or fallen away from the expected curve
  • Recurrent stomach pain, bloating or loose stools
  • Frequent infections or slow recovery from ordinary illness
  • Pale skin, unusual breathlessness, or fatigue during sport
  • Heavy periods in an adolescent girl
  • A family history of coeliac disease, thyroid or autoimmune conditions

What the Results Might Show, and What They Do Not

Low ferritin

Low ferritin with normal haemoglobin is the most common finding and the most useful, because it identifies iron deficiency at the stage where correcting it is simple. Where iron is low alongside difficulties with attention or mood, it is worth saying clearly what this does and does not mean.

Symptoms that resemble ADHD — inattention, restlessness, irritability — can also arise from disrupted sleep, low iron, or vitamin D and B12 deficiency, and these are worth identifying and correcting. That is not the same as saying they cause ADHD, and a blood test cannot rule ADHD in or out. What it can do is remove treatable contributors from the picture, either before an assessment or alongside one.

Vitamin D

Low vitamin D is expected between October and April and is straightforward to correct.

Coeliac disease and the thyroid

Positive coeliac antibodies are not a diagnosis on their own and require referral for confirmation, usually by a paediatric gastroenterologist. An abnormal TSH warrants a conversation with your doctor rather than any action at home.

Our review

Every result is reviewed by Wellth, and where something needs clinical care we will say so plainly rather than leaving you to interpret a number.

Children change

Children's needs change quickly as they grow. A growth spurt, a picky phase or a teenage girl's first periods can use up iron faster than food replaces it. When a parent feels that something has changed, it is worth taking seriously.

Order a Children's Health Panel

Frequently Asked Questions

What age is this panel suitable for?
It is designed for school-age children and adolescents. For infants and toddlers, testing should be arranged through your paediatrician or BVC rather than ordered directly, because the reference ranges and the clinical questions are different at that age.
Can low iron really affect concentration and mood?
Iron is required for the enzymes that produce dopamine and other neurotransmitters, and low iron is associated in the research literature with reduced attention, poorer memory and low mood in children — including at levels above the threshold for anaemia. Correcting a deficiency will not resolve every difficulty, but leaving one uncorrected makes everything else harder.
Does my child need to fast?
Not for this panel. Testing in the morning is preferable for the most consistent thyroid readings, but food does not need to be withheld. Making the visit easy matters more than a marginal gain in precision.
Should I test my child if nothing seems wrong?
Generally, no. Routine screening of healthy children is not recommended and can produce findings that cause worry without improving anything. This panel is for when there is a reason — a symptom, a dietary restriction, a family history, or a change you cannot explain.
What are the symptoms of iron deficiency in children?
Children with low iron are often tired, pale and irritable, find it hard to concentrate and may have a poor appetite or get infections more often. Some have restless legs at night. Because these signs are easy to put down to other things, a blood test is often the only way to know.
Do children need vitamin D?
In Sweden, all children up to the age of two are recommended vitamin D drops. Older children may also need extra, for example if they have darker skin, spend little time outdoors or seldom eat fish or foods with added vitamin D. A blood test shows whether your child's level is enough.
How do I know if my child has coeliac disease?
Coeliac disease can cause stomach pain, diarrhoea or constipation, poor growth, tiredness and iron deficiency, but some children have few obvious symptoms. It is screened for with a blood test that is only reliable while your child is still eating gluten, and the diagnosis is confirmed by a paediatrician.
Do vegetarian or vegan children need B12?
B12 is found almost only in animal foods, and it is essential for the nervous system and for growth. Children on a vegan diet need a B12 supplement, and vegetarian children may need one depending on how much dairy and egg they eat. Testing shows whether they are getting enough.
Why is my child tired all the time?
Short or late sleep, screens in the evening, recent infections, growth spurts and stress at school are common reasons. Low iron, low vitamin D and coeliac disease are among the causes a blood test can find. Contact a doctor if the tiredness comes with fever, weight loss, unusual bruising or pain. We often hear that the tiredness crept in over the course of a school term.
NW

Reviewed by

Wellth Team

Wellth

Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.

Learn more about our team →

Important to know

Wellth does not diagnose or treat disease. We work with diet, lifestyle and preventive health, alongside the care you already have.

Our reports and sessions do not replace medical advice, and a test result should not be read as a diagnosis. We use both standard healthcare reference ranges and optimal ranges. A value can therefore be normal by healthcare standards and still fall outside the range associated with good health. That does not mean disease, but it can be a chance to act early.

Supplements are only recommended by a nutritional therapist as part of a consultation, never automatically from a test result.

If anything in your results needs to be looked at by a doctor, we will tell you clearly. Contact your healthcare provider if you are worried about your health. Call 1177 for advice, or 112 in an emergency.