Children’s panel

The children’s panel comprises three basic tests most often requested by a paediatrician when a child has a fever or signs of infection: a complete blood count (CBC), C-reactive protein (CRP) and urine dipstick and sediment examination. Together, they help assess whether there is inflammation in the body, whether results are more suggestive of a bacterial or viral infection, and whether the urinary tract is the source of the fever.

Who the panel is for

• children with a fever lasting more than two to three days or without an identified cause;
• children with burning or pain on urination, frequent urination or a return to night-time urination, when a urinary tract infection is suspected;
• children with abdominal pain or cloudy, unpleasant-smelling urine;
• children who are pale, tired and have a reduced appetite;
• children after recovering from an infection, when a doctor considers a check necessary.

Do not wait for the results and contact a doctor or emergency service immediately if a child under 3 months has a temperature of 38 °C or higher, is unusually sleepy or difficult to wake, has difficulty breathing, has a rash that does not fade under the pressure of a glass, refuses fluids and passes little urine, or has seizures.

What the panel contains

Complete blood count includes the number of leucocytes (white blood cells), erythrocytes (red blood cells) and platelets, haemoglobin concentration, haematocrit, red cell indices (MCV, MCH, MCHC, RDW) and platelet indices (MPV, PDW), with an automated differential blood count (the proportion of individual leucocyte types). It shows signs of infection or inflammation, anaemia and abnormal platelet counts.

CRP is a protein produced by the liver in response to inflammation. It rises within approximately 6 hours of the onset of inflammation and peaks after about two days. High levels more often accompany bacterial infection, but CRP also rises in viral infections, so it does not identify the pathogen by itself.

Urine (dipstick and sediment): the dipstick shows, for example, leucocytes, nitrites, protein, glucose and blood in urine, while microscopic sediment examination detects cells, bacteria and crystals. In children with fever of no clear cause, it is important to check for a urinary tract infection.

Blood collection in children

A child does not need to fast for CBC and CRP, so you can feed them and give them water before blood collection; sampling is easier when a child is well hydrated. Blood collection in children is adapted to their age, and only a small amount is needed for both tests.

• Briefly and honestly explain to an older child what will happen. Promising that they “will not feel anything” undermines trust.
• Bring a favourite toy or book; you can hold a young child on your lap.
• Ask a paediatrician or pharmacist about a local skin-numbing cream; it is applied before arrival according to the instructions.
• Tell staff if the child previously found blood collection difficult or fainted.

Collecting urine from children

In older children, a midstream sample of the first morning urine or urine collected 3 to 4 hours after the last urination is best. Bring the sample as soon as possible, preferably within 2 hours, because cells break down and bacteria multiply while it stands.

• A toilet-trained child: wash the genital area with water, without disinfectant or wet wipes. Let the first part of the stream go into the toilet, collect the midstream portion in a urine container and close it tightly.
• An infant or young child in nappies: if possible, wait for the child to urinate without a nappy and catch the stream directly in a sterile container. If that does not work, use a sterile paediatric urine bag: attach it to washed, dried skin according to the manufacturer’s instructions, remove it immediately after urination and transfer the urine into a container.
• Do not squeeze urine out of a nappy, cotton wool or gauze, because such a sample is unsuitable for testing.

Urine collected in a bag is more easily contaminated by skin bacteria. If results show signs of infection, a doctor may request a new sample collected directly from the stream and a urine culture, which confirms infection and shows which antibiotic is effective. A urine culture requires a sterile container.

How to interpret the result

Reference values for children depend on age and differ from adult values, for example for leucocytes and haemoglobin. They are printed on the report. The tests are interpreted together and alongside examination of the child:

• raised leucocytes and high CRP more often accompany bacterial infection;
• normal or only slightly raised CRP in the first hours of fever does not rule out bacterial infection because CRP rises gradually, so a doctor sometimes requests a repeat;
• leucocytes and nitrites in urine and bacteria in the sediment suggest a urinary tract infection, which is confirmed by urine culture;
• low haemoglobin and small erythrocytes (low MCV) may indicate iron deficiency.

A paediatrician interprets the results because none of these tests makes a diagnosis on its own. When more information is needed, a doctor may add other tests, discussed further in the article Why CBC and CRP are not always enough.

How to arrange testing

You can have blood taken without an appointment or referral at one of our branches across Croatia (listed under Contact). Every branch accepts urine samples. Prices for all tests and panels are available in the service price list.

Frequently asked questions

Does the child need to fast?

Not for the tests in the children’s panel. If a doctor has requested other tests alongside the panel, such as glucose or lipids, check whether those require fasting.

Can CBC and CRP show whether an infection is viral or bacterial?

Only approximately. High CRP and raised leucocytes more often accompany bacterial infection, but some viruses, such as adenovirus or influenza virus, can also markedly raise CRP. The paediatrician decides on antibiotics alongside examination of the child, not from the results alone.

What CRP level is normal in children?

In healthy children CRP is very low, usually below 5 mg/L, and the limit printed on the report applies. Slightly raised CRP is common with ordinary colds; a doctor interprets it alongside the child’s symptoms.

Can I collect urine in the evening and bring it in the morning?

This is not recommended. Urine left standing for hours no longer reflects the true situation: bacteria multiply and cells break down. Collect the sample just before coming and bring it as soon as possible, preferably within 2 hours.