Any procedures that take place before the sample is analysed is known as preanalytic. This includes all steps from patient prepartion to the removal of the sample material, labelling, storage, and processing of the material, and the transport to the laboratory. Patient preparation can begin days before blood is drawn (such as taking medication, fasting, or exercise).

Many errors are possible in Preanalytics that cannot be corrected in the later analysis. This is why the reliabilty of the laboratory results is always dependent on the quality of the materials. Errors can be avoided by standardizing procedures such as patient preparation, taking of samples, among others and having the same procedures carried out where ever possible in the same way or methods.

Influence and Interference Factors

The term influence size refers to the patient. Influence sizes cause changes in vivo and are independent from the analysis method. Many cannot be influenced such as gender, race, pregnancy, age, sea level, and circadian or seasonal changes. Knowledge of these factors are important for good laboratory diagnostics with the indication of correct reference values. Factors influenceable to varying degrees by the doctor include mental stress, physical stress, smoking, drugs, and body position.

Interference factors lead in vitro after the taking of test samples to a result that does not correspond to the in-vivo concentration of the analyte. Interference factors are usually avoidable. Often the wrong sample type is selected (plasma instead of serum) or anti-coagulants, contaminants, infusions, hemolysis, lipemia interfere with the analysis. An eye on the durability of the analytes in storage and transport, as well as temperature influences, glycolysis, and clotting processes should always be kept.

Analysis Directory

 You can find specific information on the prenalaysis for each analyte in our analysis directory with details regaring the taking of the sample, materials, storage, transport, durabilty, interference factors and influences. Please note these guidelines to prevent too high or too low values. If a pre-analytical specification is violated and recognized by our lab as leading to an expected deviation of the measurement value from the true value, thus resulting in a diagnostic misinterpretion, then the lab will not perform the analysis.

If an interference factor is suspected to be the cause of an abnormal reading, the result will be commented on to that effect by a laboratory doctor. If the prescribed shelf life of a late registration is exceeded, the stability of the analyte cannot be guaranteed and therefore will not be accepted. Exceptions to the rules must be discussed with the laboratory doctors.

We will gladly advise you on questions relating to the preanalytic and interpretation of analysis results, even on the phone. You can reach us during our business hours or on mobile phone. For this purpose however, we are required to observe all data privacy laws.