Pathology tests database

Sample and container requirements

Serum

Minimum volume required

500 μL serum

Special requirements

None

Patient preparation

Patient preparation depends on whether an absorption test is being performed. No patient preparation is required if a single prednisolone measurement is required. If an absorption test is being performed then the following protocol should be used. PREDNISOLONE METABOLISM TEST Procedure: - Collect 5ml blood for baseline measurement into a plain/ gel tube (“clotted sample”) at approximately 8.30am. - Label “Pre-Prednisolone – 8.30am” - Administer standardised dose (0.5mg/kg) of Prednisolone. E.g. 60kg: 30mg. “this need to be directly observed by a medical staff” at 8.30 am. - Collect 5ml samples of blood at 9.00am, 10.00 am, 11.00 am, 12.00pm. - Please label accurately each sample time on the tube. - One request form should be completed for all samples. Please ensure patient does not take their morning dose of prednisolone prior to starting the test.

Sample viability

Turnaround time

21 days

Reference range

N/A

Clinical guidance

Prednisolone is a steroid drug used for the treatment of a number of conditions including asthma. It does not meet the normal criteria for therapeutic drug monitoring as there is no clear relationship between plasma levels and therapeutic effect. However its measurement is increasingly regarded of value as a check of compliance, and possibly to investigate patients who metabolize the drug at an abnormal rate. Patients with severe asthma are a group in which measurement may be particularly useful. Additionally, PREDAT may be requested for a short synacthen test in patients that are on prednisolone or other steroids. In these cases, both the 0 and 30 minutes specimen should be booked in for PREDAT and NOT cortisol. Cortisol by mass spectrometry is required in these patients due to interferences in the automated cortisol method. Prednisolone, prednisone, cortisone and cortisol are measured using Tandem Mass Spectrometry (LC-MS/MS) following diethyl ether extraction of steroids from plasma. Deuterated prednisolone (D6) and cortisol (D4) are used as the internal standards.

Notes