All Lifelines participants of 8 years and older participating in general assessment 1A (“Baseline”) visited a location of their choice. A trained physician's assistant performed the venapuncture, according to the Standard Operating Procedure below.

• NB: If any of the scheduled measurements in 1A Visit 1 could not be performed (for example due to temporary counter indications or technical/logistic problems), the tests could be performed during 1A Visit 2.
  

• Total duration: 20 minutes, before 10:00AM
• Retrieve the participant (and their parent(s), in case of underage participants) from the waiting room
• Collect the 24h and early morning spot, or the timed overnight urine containers
• Ask whether any urinations were missed.
• Ask whether the participant has been fasting
• Perform the venapuncture - using a butterfly needle for children
• Enter the information on the medication wrappers (if any) into the computer system
• Register all information regarding blood & urine collection into the computer system

1A Visit 2 was preceded by 1A Visit 1 by, on average, 40 days.
1A Visit 2 was accompanied by 1A Questionnaire 2 which was filled in, on average, 7 days (SD: ± 25 days) prior to 1A visit 2.
1A Visit 2 was the final part of the Baseline assessment.

1A Visit 2 is procedurally equivalent to 2A Visit 2 and 3A Visit 2. The average time between 1A Visit 2 and 2A Visit 2 was 4 years.