The role of biochemical markers in pathology
A biochemical blood test helps diagnose various conditions in children, including infectious and hematological diseases. For example, at the height of the icteric period of viral hepatitis, a sharp increase in the activity of aminotransferases is recorded, especially alanine aminotransferase (ALT), as well as a decrease in the prothrombin index. These markers reflect the degree of liver tissue damage and allow monitoring the dynamics of recovery along with bilirubin levels.
Laboratory diagnosis of iron deficiency
The diagnosis of iron deficiency anemia (IDA) is based on a comprehensive study of iron metabolism parameters, which change long before the appearance of pronounced clinical symptoms of anemia.
- Serum iron: decreases when stores are depleted.
- TIBC: compensatory increase to values above 65 µmol/L.
- Ferritin: drops below 12 µg/L (according to WHO/UNICEF criteria).
- Transferrin: iron saturation drops to 15% or less.
Modern indicators of iron-deficient erythropoiesis
In addition to classical biochemical tests, modern hematological analyzers use innovative parameters that are not affected by concomitant inflammatory processes:
- Ret-He — reticulocyte hemoglobin content (a drop below 30.6 pg indicates deficiency).
- HYPO-He — percentage of hypochromic erythrocytes (an increase above 5% indicates impaired erythropoiesis).
These indicators are indispensable for the early assessment of the effectiveness of ongoing iron therapy.
Biochemical screening in respiratory infections
The general therapeutic blood biochemistry profile for severe infections (including COVID-19) includes mandatory determination of total bilirubin, albumin, urea, creatinine, and glucose levels. Electrolytes (potassium, sodium, chlorides), ferritin level, and liver enzymes — AST and ALT — are also assessed. This allows timely detection of multiple organ dysfunction and correction of treatment strategy.
Ferritin is a «safe» for iron: if the safe is empty (<12 µg/L), the body experiences a deficiency, and TIBC (the transport system) works at maximum capacity trying to catch at least something.
Class and exam questions
Which blood biochemistry parameters will be the first to indicate liver damage in a child?
The most sensitive marker is the activity of aminotransferases, especially alanine aminotransferase (ALT), which increases sharply upon hepatocyte damage.
What are the ferritin cutoff values for diagnosing iron deficiency anemia?
According to international WHO and UNICEF criteria, a decrease in serum ferritin levels below 12 µg/L indicates the depletion of iron stores.
What are the advantages of the Ret-He indicator over standard ferritin?
The Ret-He indicator (reticulocyte hemoglobin content) does not depend on inflammatory processes, uremia, and pregnancy, unlike ferritin, which is an acute-phase protein.
What else to study on this topic
- Differential diagnosis between latent iron deficiency and manifest IDA
- Evaluation of coagulogram and hemostasis system in hemophilia
- Dynamics of bilirubin and aminotransferases in the 2nd week of the icteric period
- The role of erythrocyte indices (MCV, MCH, MCHC) in pediatric practice
- Features of the complete blood count and platelet count in viral infections
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