Urine Tests

The shipment of biological specimens must comply with the protocols established by the courier or transport service used. In some cases, air transport requires compliance with the regulations of the International Air Transport Association (IATA) for dangerous goods.

Urine samples must be clearly labelled with the specimen type because urine and serum can be grossly indistinguishable.

Noting the method by which the urine was obtained (free catch, catheterisation, cystocentesis, etc.) can be useful for interpreting the findings; for example, free-catch samples may have bacterial contaminants from the external genitalia and perineum, and catheterised samples often have a higher number of transitional or urothelial epithelial cells due to mechanical exfoliation from the passage of the catheter.

Transparent sample containers can facilitate macroscopic examination of the urine. However, if the urine is not evaluated within 30 minutes of collection, care must be taken to protect it from exposure to ultraviolet light, which causes degradation of urine components, including bilirubin.

The lids must be screwed on tightly to prevent leaks, evaporation or volatilisation of ketones (if present). Containers must not be reused because detergent residues can interfere with chemical analysis and bacterial contaminants can proliferate during storage and transit of the samples.

Urine should be stored and shipped refrigerated, although it should be borne in mind that crystal precipitation may occur. Urine is a caustic medium that causes rapid degradation of formed elements, including cells.

If a urinary tract disease reflected in the sediment examination is suspected (e.g., inflammation, infection, a proliferative process with neoplasia), cytological smears prepared from fresh urine sediment should be sent together with the urine sample. Cytological smears are air-dried.

As with other fluid samples, volume requirements apply to samples for urine testing. The preferred volume is usually 5-6 ml, although smaller volumes may be accepted, depending on the laboratory.