Study objectives: First, to determine whether intravenous injection of 1 mcg adrenocorticotropic hormone (ACTH) through short cannula, in healthy participants, provides reliable results of cortisol response, and whether this method would replace the conventional technique of injecting ACTH by a needle directly into a peripheral vein. Secondly, to determine salivary free cortisol concentration during the test in healthy controls.

Rationale of study: Intravenous injection of synthetic ACTH1-24 concentration through venous short cannula appears to be feasible and simple method. On the other hand, injection of ACTH1-24 by a needle directly into peripheral vein, is not infrequently complicated by technical problems in subjects with challenging veins. The investigators suppose that, both methods would have the same yield in predicting cortisol response.

Salivary free cortisol test has an evolving importance in assessing the adrenal function. This test would be reliable for use in low dose ACTH stimulation (1 mcg) test. The investigators will examine the concentration of salivary free cortisol during ACTH stimulation test, in order to determine level range in normal controls.

The study will include 20 healthy participants of both sexes, aged 18-70 years, that have no clinical suspicion of hypoadrenalism, or any active medical condition or treatment that might alter blood cortisol levels. Pregnant women and patients whose medical or mental condition precludes obtaining informed consent will be excluded.

In the morning of the first visit, 1 mcg of ACTH1-24 will be injected directly into a peripheral vein. Blood and salivary samples will be drawn before injection, and 30 minutes after. Salivary cortisol will be drawn also 60 minutes after injection. At least two days later, in the morning of the second visit, 1 mcg of ACTH1-24 will be injected through short cannula in a peripheral vein, followed by injection of 5 ml of normal saline. Blood and salivary samples will be drawn before injection, and 30 minutes after. Salivary cortisol will be drawn also 60 minutes after injection. Blood cortisol results and salivary free cortisol results will be compared between tests.

Inclusion Criteria:

• healthy participants of both sexes
• aged 18-70 year

Exclusion Criteria:

• any clinical suspicion of hypoadrenalism, or any active medical condition or treatment that might alter blood cortisol levels
• pregnant women and patients whose medical or mental condition precludes obtaining informed consent