The excretion of porphyrins and their precursors is most active in the early hours, which is why the sample is collected from overnight urine. The storage life of the sample is limited. Do not collect the sample a day before a mid-week holiday or weekend.

B vitamins and products containing B vitamins interfere with the interpretation of the test results. Avoid the consumption of B vitamins for ten days before the test. It is also recommended to stop taking other vitamin preparations for three days before the test.

Changes in urine during storage

Changes occur in urine during storage. They are a result of chemical reactions and bacterial effects. Make sure to seal the collecting container tightly during and after collection. Protect the container against light and store it in a cool place (+2ºC ‐ +8ºC).

Start of collection

Empty your bladder before bed as usual. This urine is not collected. Write down the collection start time to an accuracy of one minute.


Collect all urine excreted after this point of time into the collecting container. If one container is not enough, start collecting into a second one. The collection period must last at least six hours.

End of collection

Empty your bladder directly after waking up. This is the last batch of urine to be collected. The sample collection ends here. Write down the time of the last urine batch to an accuracy of one minute.


Wipe the outer surface of the collecting container dry.

The name tag is necessary for identifying the sample

Stick a label on to the side of the collecting container. Write on it your

  • name
  • social security number
  • start and end of collecting (dates and times to an accuracy of one minute)

Protect the container against light and store it in a cool place. Deliver the collecting container to the laboratory on the day of the end of collection.

Further information

For more information, please contact the customer service of Fimlab Laboratoriot Oy, tel. 03 311 74445 on weekdays from 8 a.m. to 4 p.m., or the customer service of the Ostrobothnia region, tel. (06) 213 1626 on weekdays from 7 a.m. to 3 p.m.