The influence of oral contraception on the 1 mg overnight dexamethasone suppression test

The use of oral contraceptives possibly influences the outcome of the 1 mg
Overnight Dexamethasone suppression test.
The 1 mg Overnight Dexamethasone suppression test is a frequently used
diagnostic test to exclude hypercortisolism. 1mg dexamethason is given at 23:00
and the serum cortisol is measured the morning after at 08:00h. Oral
contraception increases protein boudning of cortisol, as a result a falsely
elevated serum cortisol may be measured. Oral contraception are used
frequently. As a result of this, the interpretation of the 1 mg Overnight
Dexamethasone suppression test isoften hindered in clinical practice. The
literature is unambiguous about the inter pretation of the 1 mg Overnight
Dexamethasone suppression test when oral contraception is used. Advised is to
withdraw oral contraception before doing the 1 mg Overnight Dexamethasone
suppression test. There is no consensus about the duration of withdrawing of
oral contraception.
This study aims to determine if there is a differende in the serum cortisol
with and without use of oral contraception and if so, how long the use of oral
contraception should be withdrawn to exclude this influence

1. Examen if the outcome of the 1 mg Overnight Dexamethasone suppression test
is influenced by the use of oral contraception.
2. Examen how many weeks after ceasing the use of orale contraception the 1 mg
Overnight Dexamethason suppression test is normalized.
3. Examen if urinary and salivary cortisol are good alternatives for the
screening on hypercorticism during use of contraception.

Intervention study: cross over trial

Performing the 1 mg Overnight Dexamethasone suppression test at the end of the
third week of oral contraception. Afterwards the use of oral contraception is
ceased and is the 1 mg Overnight Dexamethason suppression test repeated at the
end of successively the first, and sixth week after ceasing oral contraceptive.
Also, urinary and salivary cortisol are collected three times for measurement
of cortisol

- Ceasing orale contrapceptives, consequently if no use of other
contraceptives: risk of pregnancy
- Risk of the 1 mg Overnight Dexamethasone suppression test. When 1 mg
Dexamethasone is taken once there are no adverse reactions expected
- 3x venepuncture and once urinary pregnancy test
- 4 visits to the hospital