Which tests matter in this situation
Why children have their own normal values
A child's body is not a scaled-down copy of an adult's. A newborn's blood is adapted to life in the womb: hemoglobin and red blood cells are very high in the first week and then fall as expected — at 2–3 months this is called the physiological low point and is not anaemia.
The white cell differential also “switches over”: until age 4–5 lymphocytes predominate (the so-called crossover), and only then does the differential become adult-like with neutrophils dominating. So lymphocytosis in a three-year-old is usually normal, not a disease.
During periods of active growth, alkaline phosphatase in children is normally 2–3 times higher than in adults — it is produced by growing bones. Comparing it with the adult reference range makes no sense.
How children are tested: in practice
In babies, blood is taken from a finger or heel; in older children, from a vein, as in adults. Little ones do not need strict fasting: for babies a 2–3-hour gap between feeds is enough, for preschoolers 3–4 hours without food, and they may drink water.
The main source of distortion is stress and crying during the draw: they briefly raise white cells and glucose. A calm child, warm hands and a good treatment room do more for an honest result than perfect fasting.
Urine from a baby is collected into a sterile urine bag after washing the genital area. Squeezing a nappy or pouring from a potty is not allowed — the laboratory has the right to reject such a sample, and the result would be unreliable.
Common situations: what usually lies behind the arrows
A slight drop in hemoglobin at 6–24 months is the most common finding: rapid growth needs a lot of iron. The paediatrician assesses it together with ferritin and MCV and decides whether correction is needed — do not give a child iron supplements on your own.
Lymphocytosis and a moderately raised ESR during or right after a respiratory infection are a typical reaction of a child's immune system. They are judged by how the child feels, not by a single line.
Truly urgent situations are rare, but they are worth knowing: very high white cells with the child feeling unwell, platelets well below normal together with unexplained bruising and bleeding, marked pallor with lethargy and refusal to eat. Here the way to the doctor is today, not “let's wait and see”.
Retesting and trends
An unexpected deviation in a child who feels well is almost always rechecked first: children's tests are sensitive to crying, a cold the day before and the quality of the draw. A retest at the same laboratory in 2–4 weeks usually settles things.
It is worth keeping reports from birth: a child's growth curve together with the trend of their test results is the best document for any doctor.
A child's report in the app
The app recognises standard laboratory reports, including children's ones, and you always check the recognised values before the breakdown. One honest limitation: children's reference ranges depend heavily on the exact age, and if the age-specific details of the report are not recognised, conclusions about a child's test should be discussed with the paediatrician.
The breakdown is informational and does not replace a paediatrician: children are a special category where only an in-person doctor makes prescriptions.
CBC reference points by age
| Age | Hemoglobin, g/L | White blood cells, ×10⁹/L | What matters |
|---|---|---|---|
| First week of life | 140–220 | 9–30 | High numbers are normal for a newborn, not anaemia or leukocytosis |
| 1–12 months | 105–140 | 6,0–17,5 | At 2–3 months — the physiological hemoglobin low point |
| 1–5 years | 110–140 | 5,5–15,5 | Lymphocytes up to 55–65% are normal (the differential “crossover”) |
| 5–12 years | 115–145 | 5,0–13,5 | The differential gradually becomes adult-like |
| Over 12 years | 120–140 (girls) / 120–160 (boys) | 4,5–13,5 | Values approach adult ones |
Practical tips
These are everyday habits, not medical prescriptions. They do not treat anything, but they make life easier and test results more honest.
- Plan tests for the morning before the first walk: the child is calmer, and the laboratory has no queues.
- Bring water — especially before a venous draw in a preschooler: dehydration makes veins “invisible”.
- Right after a respiratory infection, routine monitoring tests are postponed for 2–3 weeks unless the doctor asked otherwise: inflammation shifts white cells and ESR.
- Do not squeeze a nappy or pour from a potty — only a urine bag from the pharmacy for a urine test.
- Before the procedure, honestly explain “there will be a prick, like a mosquito bite” rather than “it won't hurt”: trust next time is worth more.
- Keep all reports in one folder or app: at a routine check-up the trend matters more than a one-off arrow.
Frequently asked questions
Is a hemoglobin of 105 in an 8-month-old baby anaemia?
Lymphocytes at 60% in a three-year-old — is that bad?
Do children need to fast before blood tests?
How do I collect a urine sample from a baby?
Do normal values differ between boys and girls?
Sources
- Clinical guidelines “Iron deficiency anaemia” — Russian Ministry of Health (cr.minzdrav.gov.ru; in Russian). Accessed: September 13, 2026.
- Clinical guidelines “Congenital hypothyroidism in children” — Russian Ministry of Health (cr.minzdrav.gov.ru; in Russian). Accessed: September 13, 2026.
- Guideline on haemoglobin cutoffs to define anaemia in individuals and populations — World Health Organization, 2024 (replaces the 2011 document; the only change in cut-offs concerns children aged 6–23 months: <105 g/L, which matches the table above). Accessed: September 16, 2026.
- Complete Blood Count (CBC): MedlinePlus Medical Test — MedlinePlus, National Library of Medicine. Accessed: September 13, 2026.
Several markers on the report?
Your child's reports by date in one app: the trend of hemoglobin and white cells from the first months — everything at hand at the paediatrician's appointment.