Präanalytik

Präanalytik is the phase before the analysis, which covers 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 every one of them is avoidable:

• Tubes are filled in the wrong order or filled short.
• Vigorous shaking instead of gentle inversion causes Hämolyse, which can make several markers unreportable.
• Samples stay at room temperature too long, or are left in the heat of a car.
• A label does not match the accompanying request form.
• A person who should have been nüchtern was not fasting.

Any one of those means 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 that prevent all of this are unglamorous and effective:

• Written Standardarbeitsanweisungen cover identification and tube order, then mixing and labelling, then storage and dispatch.
• A documented collection window matches the hours the courier actually comes.
• Training is refreshed on a schedule rather than assumed to be in place.

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.