Investigation : Cortisol
Specimen type : Serum
Spec container : Serum Gel 
Volume required : 5 ml
Turnaround : <48 hours

Reference RangeUnits
06:00h-10:00h 133 - 537nmol/l
24:00h <50

From 27/10/15 the cortisol results will be approximately 20% lower

Cortisol increases in pregnancy, with oral contraception and in stress.

A Synacthen Test is unnecessary if a 9:00 a.m. or random cortisol level is > 400 nmol/L.

Take a blood specimen for cortisol at around 9:00 a.m. and send to the lab with the form marked -"Emergency - pre-Synacthen sample", also telephone extension 4236 to inform the Duty Biochemist that you are sending a pre-Synacthen cortisol, giving the patientís name and your Bleep number. The baseline cortisol result will be phoned within 2 hours.

Cortisol < 400 : Give 250µg Synacthen intramuscularly and take serum cortisol specimens at 30 and 60 minutes post Synacthen. Send both blood specimens together to the laboratory, clearly identified with times of specimens and patientís details..


Cortisol 450 - 500 nmol/L at 30 minutes indicates adequate adrenal reserve. Cortisol > 500nmol/L at 30 minutes indicates adequate adrenal reserve. If this is not achieved until the 60 minute sample, then hypopituitarism should be considered - contact the laboratory for further advice.

Additional information on cortisol and its clinical use can be found here: cortisol.

New cortisol reference interval 01/05/21, results unaffected.

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