Basic Guide to Pediatric Hemogram

The complete blood count (CBC) is a fundamental diagnostic tool in pediatrics, offering valuable information about the three main components of blood: the red series (red blood cells), the white series (white blood cells) and platelets.

Its correct interpretation is crucial, since reference values vary significantly with the age of the child, from the neonatal period to adolescence. This guide seeks to facilitate the understanding of these parameters and their clinical implications.

The Hemoglobin It is the protein that transports oxygen. He Hematocrit It is the percentage of blood volume occupied by red blood cells.

Low values: Suggest anemia, with multiple causes in pediatrics (iron deficiency, chronic diseases, hemolysis, etc.).
High values: May indicate polycythemia (common in newborns or due to dehydration) or less common pathologies.

He VCM measures the average size of red blood cells.

Low MCV (microcytic): Suspected iron deficiency anemia (the most common cause), thalassemias.
High MCV (macrocytic): May be due to B12 or folate deficiency, liver diseases, hypothyroidism, myelodysplastic syndromes.
Normal MCV (normocytic): Anemias due to chronic disease, hemolysis, renal failure.

The CHCM indicates the concentration of hemoglobin in red blood cells. The ADE measures the variation in the size of red blood cells.

Low MCHC: Typically associated with microcytic and hypochromic anemias (iron deficiency, thalassemias).
High ADE: Indicates anisocytosis (red blood cells of varying sizes), characteristic of deficiency anemias (especially early iron deficiency).

The leukocytes They are the body's defense cells. Your total count and differential are key.

Leukocytosis: Increased white blood cells, common in infections (especially bacterial), inflammation, stress, or malignant conditions.
Leukopenia: Decrease in white blood cells, which may be due to viral infections, bone marrow suppression (drugs, diseases), or autoimmune diseases.

Important in defense against bacteria. The absolute count and percentage are evaluated.

Neutrophilia: Increase in neutrophils, an indicator of acute bacterial infection, inflammation, stress.
Neutropenia: Decrease in neutrophils, risk of infections. Causes: viral infections, drugs, bone marrow disorders.

Key in antiviral and cellular immunity.

Lymphocytosis: Increase in lymphocytes, common in viral infections (mononucleosis, chickenpox), whooping cough.
Lymphopenia: Decrease in lymphocytes, can be seen in immunodeficiencies, corticosteroid treatments, severe stress.

Eosinophils: They increase in allergies, parasitic infections, certain skin diseases.
Monocytes: They increase in chronic infections (tuberculosis), viral infections, inflammatory diseases.
Basophils: Less common, they can increase in severe allergic reactions, myeloproliferative syndromes.

The platelets They are essential for blood clotting.

Thrombocytosis: Increased platelets, common after infections, inflammation, iron deficiency. Less common in myeloproliferative disorders.
Thrombocytopenia: Decrease in platelets, risk of bleeding. Causes: Idiopathic thrombocytopenic purpura (ITP), viral infections, bone marrow suppression, sepsis.

Blood count values:

Hb: 9.8 g/dL (Normal for 2-6 years: 11.5-14.5 g/dL)
MCV: 68 fL (Normal for 2-6 years: 75-87 fL)
MCHC: 27 g/dL (Normal for 2-6 years: 31-37 g/dL)
ADE: 17.5% (Normal for 2-6 years: 11.5-15.0%)
Leukocytes and platelets: Normal

Interpretation:

The decrease in Hb, MCV and MCHC, together with an elevated RDW, is highly suggestive of iron deficiency anemia. Low MCV indicates that the red blood cells are small (microcytic) and low MCV indicates that they are pale (hypochromic). Elevated RDW reflects variability in red blood cell size, an early characteristic of iron deficiency. It is the most common type of anemia in childhood.

Blood count values:

Hb: 12.5 g/dL (Normal for 2-6 years: 11.5-14.5 g/dL)
Leukocytes: 18.0 x10⁹/L (Normal for 2-6 years: 5.0-15.0 x10⁹/L)
Neutrophils: 30% (Normal for 2-6 years: 35-55%)
Lymphocytes: 65% (Normal for 2-6 years: 35-55%)
Platelets: Normal

Interpretation:

Leukocytosis with a relative and absolute lymphocytosis (although the percentage of neutrophils decreases, the total leukocyte count is high) is typical of a viral infection. In young children, it is common to see more marked lymphocytosis in response to viral infections. The red blood cell count and platelets are within normal limits, supporting the absence of anemia or associated coagulation problems.

Blood count values:

Hb: 11.0 g/dL (Normal for 6 months - 2 years: 10.5-14.5 g/dL)
Leukocytes: 22.0 x10⁹/L (Normal for 6 months - 2 years: 6.0-17.0 x10⁹/L)
Neutrophils: 80% (Normal for 6 months - 2 years: 30-50%)
Lymphocytes: 15% (Normal for 6 months - 2 years: 40-60%)
Platelets: 550 x10⁹/L (Normal for all ages: 150-450 x10⁹/L)

Interpretation:

Leukocytosis marked with a significant neutrophilia (deviation to the left) strongly suggests a acute bacterial infection. Mild to moderate thrombocytosis is also a common response to inflammatory or infectious processes, especially bacterial ones. This pattern is a red flag for an infection that requires immediate attention.

Reference ranges in pediatrics vary significantly with age. The following table presents approximate values. Always consult your laboratory's specific reference ranges.

Age	Hb (g/dL)	Leukocytes (x10⁹/L)	Platelets (x10⁹/L)	Neutrophils (%)	Lymphocytes (%)	MCV (fL)	MCHC (g/dL)	ADE (%)

Note: These values are approximate and may vary between different laboratories and populations. Always use the reference ranges provided by the laboratory that performed the test.