Cortisol Response to Low Dose Cosyntropin Stimulation Test in the Late Afternoon

In earlier studies investigators claimed that subnormal cortisol response using plastic tubes might result from cosyntropin adherence to the tube and loss of the delivered dosage. It was shown that 21.6-58.6% of ACTH dosage had not been recovered when pushed through 20.3 cm plastic tube, and loss of ACTH may be up to 70% when cosyntropin was delivered through a plastic 30 cm scalp vein set.

Moreover, it was previously shown that afternoon cosyntropin testing was associated with a sevenfold increased likelihood of failing the 1μg test. However, in that study, investigators used a 20.3 cm plastic tube, which might have led to uncompleted cosyntropin delivery. In ther current study investigators will study afternoon 1μg cosyntropin cortisol stimulation using a short 2.5 cm tube.