CRH is corticotropin releasing hormone, also called corticoliberin. It is produced in the hypothalamus. It itself stimulates the formation and release of ACTH (adrenocorticotropic hormone), which is produced in the cells of the anterior pituitary gland. ACTH, in turn, controls the biosynthesis and secretion of hormones from the adrenal cortex.
The process
Material needed
- EDTA blood
- Blood serum
Preparation of the patient
The patient should rest two hours before starting
- Place venous access 30 minutes before
- Blood sampling for determination of ACTH (EDTA) and cortisol (serum).
- Thereafter, injection of 100 μg human CRH.
- Followed by blood sampling for determination of ACTH and cortisol after 15 min, 30 min, 45 min, 60 min, 90 min, 120 min.
Interfering factors
- None known
Indications
- Suspected anterior pituitary insufficiency.
- Cushing’s syndrome (differential diagnosis).
- Adrenocortical insufficiency (differential diagnosis).
Interpretation
Interpretation
- ACTH and cortisol basally low, no ACTH increase – pituitary ACTH deficiency.
- ACTH rise > 35% and cortisol rise > 20% – hypothalamic-pituitary Cushing’s syndrome.
- ACTH rise delayed and prolonged – hypothalamic adrenocortical insufficiency.
- Cortisol not stimulable – Cushing’s syndrome due to autonomous adrenocortical tumor.
- ACTH and cortisol not stimulable – ectopic ACTH syndrome.
- Good ACTH stimulation in tertiary adrenocortical insufficiency (hypothalamic hypofunction).
