A topic that unfortunately often receives too little attention is preanalytics, i.e. all the partial steps from obtaining the sample to its measurement. Errors during this time are the most common cause of clinically implausible results.
Since most of the sub-steps are beyond the control of the laboratory, it must be pointed out that the analytical results and findings of the IKC, HAD and AKI are only valid under the restriction that the specifications for preanalytics have been implemented correctly.
The quality of laboratory tests is strongly influenced by parameters and interfering factors, which can be controlled or excluded by correct procedures during patient preparation, blood collection, sample storage and transport.
Collection of test blood: Blood units will only be issued after two independent blood group determinations. The exception is an acute emergency with an immediate need for transfusion.
Out-of-town blood group determinations are accepted.
This form of urine is particularly suitable for bacterial testing.
The sampling time corresponds to a defined collection period, usually 24 hours. Collected urine is suitable for clinical chemistry studies, but it is unsuitable for bacterial or microscopic studies.
Spontaneous urine samples are more suitable for qualitative statements. For most questions, midstream urine is required. Precise instructions from the patient are necessary here in particular:
To ensure the determination of correct and plausible results, it is essential to comply with the relevant collection regulations. In particular, the patient must be instructed precisely:
In some cases it is necessary to collect the urine protected from light and/or cooled (see UZL analysis information system).
For several tests in collected urine, special additives are needed to prevent it from precipitating or being metabolized during collection. The table provides an overview. Exact regulations can be found at the respective parameters in the UZL analysis information system.
Summary overview of urine collection:
|Analyses that can only be performed with hydrochloric acid addition:
|Analyses that can also be performed from acidified urine:
|Analyses that can only be performed without addition :
|Ammonium (alternatively thymol/paraffin oil)
Phosphate + Clearance
VMS and HVS
Creatinine + Clearance
Delta aminolevulinic acid
Trace elements and lead (special vessel)
If analyses from urine with and without acid addition are necessary, the urine must be collected on two different days.
In the following cases, the ordered analyses are not performed: