Serumgewinnung is what happens to a sample between the draw and the analysis when serum is wanted. The blood is collected into a tube that contains no Antikoagulans, it is allowed to clot completely while standing upright, it is centrifuged, and the clear serum is then held away from the cells, either by the gel in a Serum-Gel-Röhrchen or by being pipetted off into a secondary tube. Serum is plasma without the clotting factors, which is why several routine parameters are specified for it.
Each step exists for a reason and each one can be got wrong. Clotting has to finish before the spin, because a tube centrifuged too early continues to clot afterwards and produces fibrin threads that block the analyser and cost the sample. The spin has to follow within the window the laboratory states, because as long as serum sits on the cells the two exchange material and potassium in particular rises while glucose falls, so the number reported afterwards describes the transport rather than the person. Excessive force at any point produces Hämolyse, and a haemolytic serum is rejected for several analytes no matter how carefully everything else was done.
In most pharmacy settings the centrifugation and the separation are not done on the premises, and there is no reason they should be. The laboratory has the equipment, the validation and the documented procedure for it. The pharmacy performs the draw, mixes as instructed, labels the tube and then holds the sample under the conditions the laboratory has specified until collection.
That is the point worth being blunt about. The processing is not the pharmacy responsibility, but the window before the processing entirely is. Time and temperature are set at the pharmacy counter, not in the laboratory, and once a tube has stood too long or been carried in a hot car no later care can repair it. So the collection times, the storage place and the courier rhythm are agreed as part of Probenlogistik before the service is offered, and the agreed window is written down rather than remembered.
This glossary entry is general information about German pharmacy law and practice. It is not legal advice. For binding guidance on your own pharmacy, contact your Landesapothekerkammer.
