Plain English Summary
Background and study aims
When we are stressed, the concentration of a hormone called ACTH in the blood rises. This, in turn, increases the amount of stress-hormone cortisol released from the adrenal gland. However, in intensive care unit (ICU) patients this stress response seems to be different. Our research group recently showed that during critical illness high blood levels of cortisol are, to a large extent, due a decrease in the amount of cortisol broken down in the body, rather than an increase in the amount of the hormone made. These high cortisol levels could in their turn stops the release of ACTH by what is called ‘negative feedback inhibition’. It is possible that when circulating ACTH levels remain low for too long, the patients adrenal glands may become affected, resulting in a condition called ‘relative adrenal failure’. We want to investigate how circulating cortisol and ACTH levels change over time in ICU patients. We will also look at how the adrenal glands respond to an extra stimulation by ACTH. This will allow us to gain further insights in the recovery of ACTH and cortisol levels in the blood as well as what leads to relative adrenal failure.
Who can participate?
Adult patients that have been in ICU for at least 7 days. Healthy individuals will be recruited to match with the patient group.
What does the study involve?
To investigate the changes in ACTH and cortisol during critical illness, urine samples and blood samples are collected daily from critically ill patients from day 7 until day 28 of their ICU stay. A test that stimulates the production of ACTH (ACTH stimulation test) is performed weekly. In patients staying more than 28 days, an additional blood sample, urine sample and ACTH stimulation test is taken weekly until the patient is discharged from the ICU. On the last day in ICU an additional blood sample is collected. After discharge from ICU to a regular ward, a final blood sample and ACTH stimulation test are taken on day 7 after discharge from the ICU or on the day of discharge from the hospital before day 7.
What are the possible benefits and risks of participating?
There will be no immediate benefits or risks for participants in the study. Taking a small amount of blood on day 7 after discharge from the ICU may cause mild pain, bruises or minimal bleeding.
Where is the study run from?
Five ICUs of the University Hospitals of Leuven (Belgium).
When is the study starting and how long is it expected to run for?
December 2014 to November 2015
Who is funding the study?
Methusalem (long term structural funding by the Flemish Government, Belgium), Research Foundation - Flanders (FWO) (Belgium) to the KU Leuven.
Who is the main contact?
Prof. Dr. Greet Van den Berghe
Prof Greet Van den Berghe
University Hospitals Leuven (UZ Leuven)
Head Laboratory of Intensive Care Medicine
Department Cellular and Molecular Medicine
University of Leuven (KU Leuven)
On the dynamics of the hypothalamus-pituitary-adrenal axis response to prolonged critical illness: a prospective observational study
Dynamic Adrenal Study (DAS)
Recently it was shown that during critical illness reduced cortisol metabolism contributes to hypercortisolism while cortisol production is only mildly elevated, if at all [Boonen et al., NEJM 2013]. Maintaining high circulating cortisol levels could suppress ACTH secretion via negative feedback inhibition. It remains unknown whether/when ACTH secretion recovers in ICU patients and whether/when the continuously suppressed circulating ACTH during prolonged critical illness is causing adrenal insufficiency. Also, the use of a single ACTH stimulation test for the diagnosis of adrenal failure in this condition is highly debated, because it is poorly reproducible in critically ill patients and may simply reflect the degree of negative feedback inhibition exerted by the cortisol that is not broken down. Therefore our primary objective is to characterize the time course of the HPA-axis changes and the response to exogenous ACTH during prolonged critical illness and upon recovery. Our secondary objective is to address the causes/consequences of these changes.
Ethics Committee (Institutional Review Board) of the University Hospitals Leuven, 30/10/2014, ref: ML11107
Observational cohort study
Primary study design
Secondary study design
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
To evaluate the evolution of the HPA-axis alterations during critical illness, 24h-urine collection samples and blood samples (4 ml) will be collected daily in critically ill patients from day 7 until day 28 of their ICU stay to determine evolution of ACTH and cortisol plasma concentrations and urine cortisol metabolites. A short ACTH-stimulation test (injection of 250 μg Synacthen®) will be performed weekly. In patients staying more than 28 days, a minority of the ICU population, an additional blood sample (4 ml), 24 h urine collection and ACTH-stimulation test will be taken weekly until ICU discharge or death. On the last day in ICU an additional blood sample (4 ml) will be collected to quantify plasma ACTH and cortisol concentrations at recovery/death. After discharge from the ICU, a final blood sample and ACTH stimulation test will be taken on day 7 post-ICU or on the day of discharge in patients discharged from the hospital before day 7.
Primary outcome measure
1. Determination of the evolution of ACTH and cortisol plasma concentrations and urine cortisol metabolites during prolonged critical illness and upon recovery, in comparison with ACTH and cortisol plasma concentrations of healthy volunteers.
2. To characterize the time course of the response to exogenous ACTH during prolonged critical illness and upon recovery, in comparison with response to exogenous ACTH in healthy volunteers.
Secondary outcome measures
Further mechanistic analyses using clinical and laboratory parameters.
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Critically ill patients admitted for ≥7 days to one of the five ICUs from two departments (medical and surgical) in the University Hospitals Leuven
2. Age ≥18 years
For healthy volunteers:
1. Age-, gender- and BMI-matched to the included patients
Target number of participants
At least 542 patients (not receiving exogenous steroids) staying more than 7 days at the ICU and 20 healthy matched volunteers
Participant exclusion criteria
1. Predisposing factors of adrenal insufficiency:
1.1. Cerebral disease with intracranial hypertension threatening the neuroendocrine system
1.2. Pituitary disorders including (pan)hypopituitarism
1.3. Known adrenal disease (Cushing's syndrome or Addison's disease)
1.4. Treatment with glucocorticoids, other steroids or anti-steroid chemotherapy within the last 3 months
1.5. Use of etomidate within the last 72 hours
1.6. Other drugs predisposing to adrenal insufficiency: azoles, phenytoin, rifampicin, glitazones, imipramin, phenothiazine, phenobarbital
2. No arterial line in place
3. Ethical restrictions:
3.2. Declined participation
For healthy volunteers:
1. Recent history of treatment with HPA-axis interfering drugs
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
University Hospitals Leuven (UZ Leuven)
Methusalem (long term structural funding by the Flemish Government, Belgium), Research Foundation - Flanders (FWO) (Belgium)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
To be confirmed at a later date
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
2018 results in: https://www.ncbi.nlm.nih.gov/pubmed/30215187