A normal result does not exclude
Cushings, but makes it unlikely. Repeated measurement of
urine cortisol may be required as some patients with
Cushing’s syndrome may have non diagnostic urine cortisol
values. Normal urine cortisol excretion on three separate
occasions excludes Cushing’s syndrome.
Cortisol production and
therefore urinary excretion increases during stress, for
example during surgery, acute illness and following trauma.
Production (and hence excretion) may be reduced in
starvation and in pregnancy.