The immune system's first response
At the first meeting with the pathogen, the body begins to produce IgM - large antibodies that effectively bind microbes, but do not last long in the blood. After a few weeks, they are replaced by IgG, which provides long-term protection. This pattern underlies the diagnosis of infections: the detection of specific IgM indicates acute or recent infection, while the presence of only IgG indicates a previous infection or formed immunity. The determination of total IgM is used to assess the state of the immune system: a decrease is typical for immunodeficiencies, a significant increase is for Waldenström's macroglobulinemia and chronic infections. In newborns, their own IgM in the blood is a sign of intrauterine infection, since it does not pass through the placenta.
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.