What question does the test solve?
Elevated blood amylase does not always mean pancreatitis. There is a condition - macroamylasemia, in which amylase binds to large plasma proteins, ceases to be filtered by the kidneys and accumulates in the blood. The person is healthy, but the analysis looks alarming for years and leads to unnecessary examinations. The clearance ratio distinguishes these situations: in acute pancreatitis, the excretion of amylase in the urine increases and the rate increases, in macroamylasemia it sharply decreases. For the calculation, you need both blood and a portion of urine with the determination of amylase and creatinine in both media.
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.