Urinary cortisol (24-hour urine collection) – laboratory test

Description

Measuring free cortisol levels in a 24-hour urine collection reflects the average level of free cortisol in the blood over the collection period. However, this test is mainly used to diagnose hypercortisolaemia, because under normal physiological conditions, only the free fraction of the hormone (not bound to proteins) is filtered by the kidneys. A significant increase in urinary cortisol excretion occurs only when its serum concentration exceeds the binding capacity of plasma proteins.

Collect urine in a dry, clean container of sufficient capacity (approx. 2 – 2,5 l). The laboratory has graduated containers available. Start the collection in the morning (e.g. 7.00) and finish at the same time the following day:
– discard the first urine passed in the morning (into the toilet),
– collect all subsequent urine in the prepared container, including the first urine passed the following morning,
– keep the urine container in a dark, cool place throughout the collection period,
– once the collection is complete, measure the total amount of urine collected and record the volume (in millilitres),
– mix the urine, pour a 30 – 50 ml sample into a urine specimen container and deliver it to the laboratory.

If, for any reason, even one portion of urine passed during the collection period is not transferred to the collection container, the test will not be accurate. In this case, repeat the urine collection on another day.

Results available in: approx. 6 working days

You can find the opening days and hours of our collection points HERE .