The basis of long-term immunity
IgG makes up about 75 percent of all blood antibodies and is responsible for long-term protection: it is these antibodies that persist for years after an infection or vaccination. IgG is the only class of antibodies that passes through the placenta, due to which the newborn is protected by maternal immunity during the first months of life. The determination of total IgG is used to assess the humoral component of immunity: a persistent decrease is characteristic of primary immunodeficiencies and indicates the risk of severe bacterial infections, an increase is for chronic infections, autoimmune diseases and monoclonal gammopathies. Specific IgG to specific pathogens is used to confirm previous infection and assess post-vaccination immunity.
Why preparation is so important
The laboratory result is a number, but the correct number can only be obtained if the rules are followed. Eating changes the levels of glucose, lipids and a number of enzymes significantly; physical activity the day before increases CK and AST; smoking affects hormones; time of day is critical for cortisol and testosterone.
Therefore, a “bad analysis” often turns out to be a consequence of impaired preparation, and not an illness, and leads to unnecessary examinations and prescriptions.
General rules for donating blood
- on an empty stomach 8–12 hours, you can drink water
- Eliminate alcohol and intense exercise per day
- no smoking in an hour
- donate blood before physiotherapy, x-rays and massage
- Take medications in advance by agreeing with your doctor
- for hormones in women, take into account the day of the cycle
How to read the result
Reference values depend on the method and equipment of the laboratory, so it is correct to compare results only within the same laboratory. A deviation of a few percent from the normal limit in itself rarely matters - the overall picture and dynamics are important. It is up to the physician to interpret the analysis: an isolated indicator without a clinical context is often misleading.