Präanalytik

Präanalytik is the phase before the analysis: how the person was prepared, how the sample was identified, how it was collected, how it was stored and how it reached the laboratory. It is where the large majority of laboratory errors originate.

The failures repeat themselves across pharmacies and they are all avoidable. Tubes filled in the wrong order or filled short. Vigorous shaking instead of gentle inversion, which causes Hämolyse and can make several markers unreportable. Samples left at room temperature too long, or exposed to heat in a car. A label that does not match the request form. A person who should have been nüchtern and was not.

Any one of those turns into a rejected sample. For a pharmacy that means calling the customer back for a second venöse Blutentnahme, which costs goodwill as well as the consumables.

The controls are unglamorous and effective. Written Standardarbeitsanweisungen covering identification, tube order, mixing, labelling, storage and dispatch. A documented collection window that matches the courier. Training that is refreshed rather than assumed.

The akkreditiertes Labor receiving the sample sets the requirements, and they are not negotiable. Asking for the laboratory's Präanalytik handbook before the first draw is the single most useful preparation step, because it defines tube types, volumes, transport times and temperatures for every analysis the pharmacy plans to offer.

A value close to a Referenzbereich limit deserves a Präanalytik question before it deserves a clinical one.