Adrenocortical function: an indicator of severity of disease and survival in chronic critically ill patients

A characterization of cortisol level and adrenal reservation in human cardiopulmonary arrest: systematic review and meta-analysis

BACKGROUND

Cardiopulmonary arrest (CPA) is an urgency, which is associated with high mortality. This systematic review evaluated the relationship between baseline cortisol level and the outcome of resuscitated CPA patients.

METHODS

We searched the following databases: PubMed, Scopus, ISI Web of Science, and Google Scholar. Relevant observational and controlled trials were explored from inception by April 2020. The quality of the articles was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Finally, five cohort studies (n = 201 participants in total) were eligible for including in the meta-analysis. The results of this meta-analysis showed that although the baseline serum cortisol levels were higher in survivors of cardiac arrest compared with non-survivors, the differences between groups do not reach a significance level (Hedges' g = 0.371, 95% CI, -0.727, 1.469, P value = 0.508). Between-study heterogeneity was statistically significant (Cochrane Q test: P value < 0.001, I2 = 89.323).

CONCLUSIONS

The result of the present meta-analysis was suggestive of a higher baseline serum cortisol levels in survivors of CPA. Future randomized controlled studies with a large sample size will determine the exact relationship between adrenal reservation and the eventual outcome of patients with CPA.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018085468.

Critical illness-related corticosteroid insufficiency in dogs with systemic inflammatory response syndrome: A pilot study in 21 dogs

Critical illness-related corticosteroid insufficiency (CIRCI) refers to a lack of adequate corticosteroid activity, which occurs in up to 48% of dogs with sepsis. However, data regarding the occurrence of CIRCI in critically-ill dogs are still scarce. This study aimed to assess: (1) the relationship between CIRCI and clinicopathological inflammatory markers, hypotension and mortality; and (2) the impact of low-dose hydrocortisone treatment on survival. Twenty-one dogs diagnosed with systemic inflammatory response syndrome (SIRS) were enrolled in a prospective case-control study. All dogs were initially evaluated for adrenal function with an ACTH stimulation test and dogs with Δcortisol ≤ 3 μg/dL were diagnosed with CIRCI. Mean arterial pressure (MAP), white blood cell (WBC), band neutrophils (bNs), c-reactive protein (CRP), and 28-day mortality rate were assessed. Fourteen dogs were treated with low-dose hydrocortisone. The relationships between CIRCI and MAP, WBC, bN, CRP, basal cortisol and mortality were investigated, as was the association between mortality and hydrocortisone treatment. Ten of 21 (48%) dogs were diagnosed with CIRCI. Increased bNs were associated with the presence of CIRCI (P = 0.0075). CRP was higher in dogs with CIRCI (P = 0.02). Fourteen of 21 (66%) dogs died during the study (6/14 had CIRCI). Basal hypercortisolemia (>5 μg/dL) was associated with increased risk of mortality (P = 0.025). Based on our diagnostic criteria, CIRCI occurs frequently in dogs with SIRS and was associated with increased bNs and increased CRP. In this study, CIRCI and low-dose hydrocortisone treatment were not significantly associated with mortality, but basal hypercortisolemia was associated with increased mortality.

Investigation of serum cortisol concentration as a potential prognostic marker in hospitalized dogs: a prospective observational study in a primary care animal hospital

BACKGROUND

Dogs with various medical diseases are usually treated at hospitals; however, the prognostic markers in dogs remain unknown. The aim of this study was to investigate the ability of serum cortisol concentration (SCC) to predict the prognosis of dogs with medical diseases. At 0 and 24 h after hospitalization, the neutrophil count, lymphocyte count, blood glucose concentration, and SCC were measured. Survival for 30 days from the time of hospitalization was investigated, and the dogs were divided into a survivor group and a non-survivor group.

RESULTS

The neutrophil count at 24 h, SCC at 24 h, increase in SCC from 0 to 24 h (Inc-SCC), and the rate of increase in SCC from 0 to 24 h (R-Inc-SCC) were significantly higher in the non-survivor group than in the survivor group. The area under the receiver operating characteristic (ROC) curve values for the neutrophil count at 24 h, SCC at 24 h, Inc-SCC, and R-Inc-SCC were 0.695, 0.72, 0.63, and 0.66, respectively. Using the highest area under the ROC curve value, the sensitivity and specificity of SCC at a cutoff level of 6.6 μg/dL for predicting mortality were 89.5 and 61.9%, respectively. Moreover, the Kaplan-Meier curves confirmed the significant prognostic influence of SCC at 24 h.

CONCLUSIONS

SCC as a marker of stress is a useful biomarker for predicting the prognosis of dogs with medical diseases requiring hospital treatment.

Stress hyperglycemia: A prospective study examining the relationship between glucose, cortisol and diabetes in myocardial infarction

AIM

We aimed to explore the relationship between stress, hyperglycemia and diabetes in myocardial infarction (MI), using serum cortisol as a surrogate marker for the severity of stress.

METHODS

Subjects with acute MI were prospectively recruited upon hospital admission. Serum glucose and cortisol were measured in addition to standard testing. Subjects were defined as having stress hyperglycemia (SH) if they had an admission glucose ≥7.8 mmol/L without a history of glucose intolerance. Subjects were followed up with glucose tolerance testing post-discharge.

RESULTS

Of the 200 subjects in the study, 58 had known diabetes/impaired glucose tolerance (IGT), and 45 had SH. There was a positive association between admission glucose and cortisol for the entire cohort (r_s = 0.26, p < 0.01). This relationship was present in the subgroup who had SH and then normal glucose post-discharge (r_s = 0.53, p = 0.03), but not in SH subjects who had diabetes/IGT on post-discharge testing. It was also evident amongst all subjects with normal glucose (r_s = 0.46, p < 0.01), but not those with diabetes/IGT in general. On multivariate analysis, admission glucose was a positive predictor and cortisol a negative predictor of abnormal glucose tolerance.

CONCLUSIONS

Our data suggests that SH with MI reflects either underlying glucose intolerance or more severe stress in people without glucose intolerance.

Evaluation of Random Plasma Cortisol and the Low Dose Corticotropin Test as Indicators of Adrenal Secretory Capacity in Critically Ill Patients: A Prospective Study

It is unclear whether a random plasma cortisol measurement and the corticotropin (ACTH) test adequately reflect glucocorticoid secretory capacity in critical illness. This study aimed to determine whether these tests provide information representative of the 24 hour period.

Plasma cortisol was measured hourly for 24 hours in 21 critically ill septic patients followed by a corticotropin test with 1 μg dose administered intravenously. Serum and urine were analysed for ACTH and free cortisol respectively. Marked hourly variability in plasma cortisol was evident (coefficient of variation 8–30%) with no demonstrable circadian rhythm. The individual mean plasma cortisol concentrations ranged from 286±59 nmol/l to 796± 83 nmol/l. The 24 hour mean plasma cortisol was strongly correlated with both random plasma cortisol (r2 0.9, P<0.0001) and the cortisol response to corticotropin (r2 0.72, P<0.001). Only nine percent of patients increased their plasma cortisol by 250 nmol/l after corticotropin (euadrenal response). However, 35% of non-responders had spontaneous hourly rises >250 nmol/l thus highlighting the limitations of a single point corticotropin test. Urinary free cortisol was elevated (865±937 nmol) in both corticotropin responders and non-responders suggesting elevated plasma free cortisol. No significant relationship was demonstrable between plasma cortisol and ACTH.

We conclude that although random cortisol measurements and the low dose corticotropin tests reliably reflect the 24 hour mean cortisol in critical illness, they do not take into account the pulsatile nature of cortisol secretion. Consequently, there is the potential for erroneous conclusions about adrenal function based on a single measurement. We suggest that caution be exercised when drawing conclusions on the adequacy of adrenal function based on a single random plasma cortisol or the corticotropin test.

Prognostic Value of Relative Adrenal Insufficiency During Cardiogenic Shock: A Prospective Cohort Study With Long-Term Follow-Up

BACKGROUND

Relative adrenal insufficiency (RAI) is common in intensive care unit patients, particularly during septic shock (SS). Cardiogenic shock (CS) may share some pathophysiological features with SS. The aim of this study was to evaluate the prevalence and long-term prognosis of RAI during CS.

PATIENTS AND METHODS

Prospective observational study conducted in the intensive care and cardiology units in one university hospital in France. Patients meeting the criteria for CS without prior corticosteroid therapy were included. Total blood cortisol levels were assessed immediately before (T0) a short corticotropin stimulation test (0.25 mg i.v. of tetracosactrin) and 30 and 60 min afterward. Δmax was defined as the difference between the maximal value after the test and T0.

RESULTS

Of the 92 patients enrolled, 42 (46%) (95% confidence interval [CI] [36%-56%]) died in hospital and 7 more died during a median follow-up of 616 [57-2,498] days, for an overall mortality rate of 53% (95% CI [43%-63%]). Three groups were identified based on the corticotropin test: group 1 (T0 ≤798 nmol/L and Δmax >473 nmol/L), group 2 ([T0 >798 nmol/L and Δmax >473 nmol/L] or [T0 ≤798 nmol/L and Δmax ≤473 nmol/L]), and group 3 (T0 >798 nmol/L and Δmax ≤473 nmol/L) with an overall survival of 76%, 43%, and 15%, respectively (log rank P = 0.003). In the multivariable analysis, adrenal nonresponse (group 3) was an independent predictor of mortality (P = 0.04), along with left ventricular ejection fraction, Simplified Acute Physiology Score II, and cardiac arrest.

CONCLUSIONS

These data suggest that a short corticotropin test has a good prognostic value in CS and allows identifying patients at higher risk of death.

Time-dependent association of glucocorticoids with adverse outcome in community-acquired pneumonia: a 6-year prospective cohort study

Background

The hypothalamic-pituitary-adrenal stress axis plays a crucial role in community-acquired pneumonia (CAP), with high cortisol being associated with disease severity and corticosteroid treatment resulting in earlier time to recovery. Our aim in the present study was to compare different glucocorticoid hormones, including cortisol, 11-deoxycortisol, cortisone, and corticosterone, regarding their association with short- and long-term adverse outcomes in a well-defined CAP cohort.

Methods

We prospectively followed 285 patients with CAP from a previous Swiss multicenter trial for a median of 6.1 years and measured different admission glucocorticoid serum levels by liquid chromatography coupled with tandem mass spectrometry. We used adjusted Cox regression models to investigate associations between admission hormone levels and all-cause mortality at different time points.

Results

Mortality was 5.3% after 30 days and increased to 47.3% after 6 years. High admission cortisol was associated with adverse outcome after 30 days (adjusted OR 3.85, 95% CI 1.10–13.49, p = 0.035). In the long term (i.e.,), however, high admission cortisol was associated with better survival (adjusted HR after 3 years 0.53, 95% CI 0.32–0.89, p = 0.017; adjusted HR after 6 years 0.57, 95% CI 0.36–0.90, p = 0.015). Compared with 11-deoxycortisol, cortisone, and corticosterone, cortisol showed the highest association with mortality.

Conclusions

Among different glucocorticoid hormones, cortisol showed the highest association with mortality in CAP. Whereas a more pronounced glucocorticoid stress response on hospital admission was associated with higher short-term adverse outcome, long-term outcome was favorable in these patients. These data should support the correct interpretation of glucocorticoid blood data.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1656-7) contains supplementary material, which is available to authorized users.

Controversies surrounding critical illness-related corticosteroid insufficiency in animals

OBJECTIVES

To describe the controversies surrounding critical illness-related corticosteroid insufficiency (CIRCI) and the use of hydrocortisone in critically ill patients, and to present published diagnostic and therapeutic strategies in companion veterinary species.

ETIOLOGY

Critical illness-related corticosteroid insufficiency may be due to hypothalamic-pituitary-adrenal (HPA) axis dysfunction, alterations in cortisol-plasma protein binding, target cell enzymatic changes, changes in glucocorticoid receptor (GR) function, or a combination of these or other factors present during critical illness.

DIAGNOSIS

Appropriate tests to diagnose CIRCI are unknown. The diagnosis in people is currently based on response to treatment with hydrocortisone. There is currently no consensus on appropriate diagnostic feature(s) in veterinary species.

THERAPY

Low-dose hydrocortisone is the treatment of choice for patients with CIRCI.

PROGNOSIS

If the patient survives the critical illness, prognosis for resolution of CIRCI and hydrocortisone dependence is very good.

Increased Total Serum Random Cortisol Levels Predict Mortality in Critically Ill Trauma Patients

Dysfunction in the hypothalamopituitary adrenal axis is thought to exist; however, there continues to be controversy about what level of serum cortisol corresponds to adrenal insufficiency. Few studies have focused on the significance of serum random cortisol in the critically ill trauma patient. Trauma patients with total serum random cortisol levels drawn in the intensive care unit within the first seven days of hospitalization were retrospectively reviewed. The primary outcome measured was in-hospital mortality. Two hundred forty-two patients were analyzed. Non-survivors had significantly higher mean cortisol levels than survivors (28.7 ± 15.80 mg/dL vs 22.9 ± 12.35 mg/dL, P = 0.01). Patients with cortisol 30 mg/dL or greater were more likely to die with odds ratio of 2.7 (95% confidence interval [CI], 1.5 to 5). The odds ratio increased to 4.0 and 3.8 (95% CI, 1.4 to 11.4 and 1.3 to 10.9) when cortisol was drawn on hospital Day 2 and Days 3 through 7, respectively. Among nonsurvivors, patients with an injury severity score less than 25 had significantly higher cortisol levels than patients with an Injury Severity Score 25 or higher (35.3 ± 19.21 mg/dL vs 25.7 ± 13.21 mg/dL, P = 0.009). Patients with massive transfusion, traumatic brain injury, spinal cord injury, or solid organ injury did not have significantly different cortisol levels. The covariate-adjusted area under the receiver operating characteristic curve indicated that cortisol level has a 77 per cent accuracy in differentiating survivors from nonsurvivors. Higher cortisol levels were predictive of mortality in critically ill trauma patients. Whether serum cortisol level is a marker that can be modified remains an area of interest for future study.

Evaluation of endocrine function in children admitted to pediatric intensive care unit

BACKGROUND

Although studied widely in adulthood, little is known about endocrinological disorders during critical illnesses in childhood. The aims of this study were to define the endocrinological changes in patients admitted to pediatric intensive care unit (PICU) and to identify their effects on prognosis.

METHODS

Forty patients with a mean age of 5.1 years admitted to PICU were enrolled in the study. Blood samples were taken at admission and at 24 and 48 h to measure cortisol, adrenocorticotropic hormone (ACTH), prolactin, growth hormone (GH), GH binding protein (GHBP), insulin-like growth factor-binding protein-3 (IGFBP-3) and interleukin-6 (IL-6). The severity of the patient's condition was assessed using pediatric risk of mortality (PRISM) and pediatric logistic organ dysfunction (PELOD) scores.

RESULTS

PRISM and PELOD scores were significantly higher in non-survivors. Cortisol, ACTH, prolactin, GH, GHBP, IGFBP-3 and IL-6 were not significantly different between the survivors and non-survivors. There was a negative correlation between baseline IGFBP-3 and PRISM scores. A positive correlation was seen between cortisol level at 24 h and PRISM score. On multivariate linear regression analysis, PRISM score was best explained by ACTH and cortisol at 24 h. A positive weak correlation was detected between IL-6 at 24 h and PELOD scores.

CONCLUSIONS

Although there was no difference between survivors and non-survivors regarding the studied endocrine parameters, there were associations between cortisol, ACTH, IL-6 and IGFBP-3 and risk assessment scores, and, given that these scores correlated with mortality, these parameters might be useful as prognostic factors.

Hypothalamic-pituitary hormones during critical illness: a dynamic neuroendocrine response

Independent of the underlying condition, critical illness is characterized by a uniform dysregulation of the hypothalamic-pituitary-peripheral axes. In most axes a clear biphasic pattern can be distinguished. The acute phase of critical illness is characterized by low peripheral effector hormone levels such as T3, IGF-1 and testosterone, despite an actively secreting pituitary. The adrenal axis with high cortisol levels in the presence of low ACTH levels is a noteworthy exception. In the prolonged phase of critical illness, low peripheral effector hormone levels coincide with a uniform suppression of the neuroendocrine axes, predominantly of hypothalamic origin. The severity of the alterations in the different neuroendocrine axes is associated with a high risk of morbidity and mortality, but it remains unknown whether the observed changes are cause or consequence of adverse outcome. Several studies have identified therapeutic potential of hypothalamic releasing factors, but clinical outcome remains to be investigated with sufficiently powered randomized controlled trials.

Adrenal insufficiency in cardiothoracic patients: an evaluation of the corticotrophin stimulation test and other diagnostic methods

PURPOSE

The purposes of the study were to determine the incidence of adrenal insufficiency (AI) using several published techniques, compare the response rates using a low-dose (LD) corticotropin (ACTH) stimulation test vs a standard dose (SD), and identify the technique that is most closely related to vasopressor use.

MATERIALS AND METHODS

Consecutive adult patients who were undergoing open heart surgery for CAD or valvular disease were prospectively enrolled. Exclusion criteria included history of steroid use, operative steroid, or etomidate administration. Postoperatively, each patient underwent ACTH stimulation with 1 μg (LD) and 249 μg (SD), 60 minutes apart. Agreement among the tests was evaluated, and vasopressor use was compared between groups.

RESULTS

There were 40 patients evaluated. The incidence of AI based on operative change, postoperative values, and LD-ACTH and SD-ACTH tests was 53%, 38%, 60%, and 38%, respectively. Agreement between the LD- and SD-ACTH tests was 73% (κ = 0.476, P = .001). There was a significant difference in the need for (93% vs 52%, P = .013) and duration (18.9 [0-180.6] vs 0.6 [0-73.2] hours, P = .003) of vasopressor therapy in patients with and without AI but only using the SD-ACTH definition.

CONCLUSION

The incidence of AI will vary greatly based on technique used for diagnosis. The SD-ACTH stimulation test should be used to determine AI in open heart patients postoperatively because of the close association with vasopressor usage.

Adrenocortical (dys)function in septic shock - a sick euadrenal state

A central feature of the endocrine pathophysiology of septic shock is thought to be the existence of adrenal dysfunction. Based on changes in glucocorticoid secretion and responsiveness, protein binding, and activity. These changes have been described by the terms "Relative Adrenal Insufficiency" (RAI), or "Critical Illness Related Corticosteroid Insufficiency" (CIRCI), and form part of the rationale for trials of glucocorticoid treatment in septic shock. Diagnostic criteria for these conditions have been based on plasma cortisol profiles and have proven notoriously difficult to establish. The uncertainty in this area arises from the inability of current tests to clearly identify who is truly glucocorticoid "deficient" at a cellular level, and hence who requires supplemental glucocorticoid administration. Emerging data suggest that there may be abnormalities in the tissue activity of glucocorticoids in patients with severe sepsis and plasma profiles may not be reliable indicators of tissue glucocorticoid activity, We put forward an alternative point of view, that is the spectrum of adrenocortical dysfunction in sepsis - plasma and tissue, can be grouped under the umbrella of a "sick euadrenal syndrome" rather than an adrenocortical insufficiency.

Role of human recombinant activated protein C and low dose corticosteroid therapy in sepsis

Despite advances in modern medicine, sepsis remains a complex syndrome that has been associated with significant morbidity and mortality. Multiple organ failure associated with sepsis leads to high mortality and morbidity. About 28 - 50% deaths have been reported in patients with sepsis. The number of sepsis patients is increasing, with considerable burden on healthcare facilities. Various factors leading to a rise in the incidence of sepsis are (1) Improvement of diagnostic procedures (2) Increase in the number of immunocompromised patients taking treatment for various autoimmune disease, carcinomas, organ transplantation (3) Advances in intensive procedures (4) Nosocomial infections (5) Extensive use of antibiotics. With the better understanding of sepsis various modalities to modify pathophysiological response of septic patients have developed. Activated protein C and low-dose corticosteroid therapy have been tried in patients, with variable results.

Relative adrenal insufficiency in the intensive care population; background and critical appraisal of the evidence

Dysfunction of the hypothalamo-pituitary adrenal axis has become a central feature in descriptions of the pathophysiology of sepsis. However; despite hundreds of published articles including literature reviews and consensus statements, controversy still exists regarding the fundamental nature of the disorder and its relevance to clinical management. Often referred to as 'relative adrenal insufficiency', a recent consensus conference has proposed the alternate term 'critical illness related corticosteroid insufficiency' and suggested diagnostic criteria of a delta serum cortisol of less than 9 microg/l after adrenocorticotrophic hormone administration or a random total cortisol of under 10 microg/l. This review attempts to establish a critical reappraisal of the evidence for the existence of relative adrenal insufficiency/critical illness related corticosteroid insufficiency in patients with sepsis and examines the background, controversies and possibilities for future research into the condition.

Prevalence of occult adrenal insufficiency and the prognostic value of a short corticotropin stimulation test in patients with septic shock

Background:

Corticosteroid insufficiency in acute illness can be difficult to discern clinically. Occult adrenal insufficiency (i.e., Δmax ≤9 μg/dL) after corticotropin may be associated with a high mortality rate.

Objective:

To assess the prevalence of occult adrenal insufficiency and the prognostic value of short corticotropin stimulation test in patients with septic shock.

Materials and Methods:

A total of 30 consecutive patients admitted in the adult intensive care unit of the Sheri Kashmir Institute of Medical Sciences who met the clinical criteria for septic shock were prospectively enrolled in the study. A low dose (1 μg) short corticotropin stimulation test was performed; blood samples were taken before the injection (T0) and 30 (T30) and 60 (T60) minutes afterward.

Results:

The prevalence of occult adrenal insufficiency was 57%. The 28-day mortality rate was 60% and the median time to death was 12 days. The following seven variables remained independently associated with death: organ system failure scores, simplified acute physiology score II score, mean arterial pressure, low platelet count, PaO₂:FIO₂, random baseline cortisol (T0) >34 μg/dL, and maximum variation after test (Δmax) of ≤9 μg/dL. Three different mortality patterns were observed: (I) low (T0 ≤34 μg/dL and Δmax >9 μg/dL; a 28-day mortality rate of 33%),(II) intermediate (T0 >34 μg/dL and Δmax >9 μg/dL or T0 ≤34 μg/dL and Δmax ≤9 μg/dL; a 28-day mortality rate of 71%), and (III) high (T0 >34 μg/dL and Δmax ≤9 μg/dL; a 28-day mortality rate of 82%).

Conclusion:

A short corticotropin test using low-dose corticotropin (1 μg) has a good prognostic value. High basal cortisol and a low increase in cortisol on corticotropin stimulation test are predictors of a poor outcome in patients with septic shock.

Decreased cytosolic glucocorticoid receptor levels in critically ill patients

The immune system and the hypothalamic-pituitary-adrenal axis are linked by several mechanisms. Intracellular glucocorticoid receptors represent one important connection. The aim of this study was to examine the coherence between the number of glucocorticoid receptors, activation of the hypothalamic-pituitary-adrenal axis, inflammatory cytokine levels and the severity of illness in critically ill patients. In a prospective study, blood was collected from 20 healthy members of the hospital staff (control group) and 50 ventilated patients (sample group) within the first 24 hours after intubation and within three days of extubation. 3H-dexamethasone-binding assay was used to assess cytoplasmatic free glucocorticoid receptors levels. ACTH, cortisol, IL-6 and TNFa levels were measured by ELISA. In the sample group, specific binding of 3H-dexamethasone was significantly decreased compared to the control group. Glucocorticoid receptor levels tended to be lower in more severely ill patients. Plasma cortisol and ACTH levels were significantly different from the control group after extubation but not at intubation. Severe illness is associated with rapid down-regulation of 3H-dexamethasone binding. This decrease occurs before elevation of plasma cortisol. Therefore, down-regulation of cortisol binding may be directly associated with the stress response and not due to feedback regulation following increase in plasma cortisol levels.

"Relative" adrenal insufficiency in critical illness

OBJECTIVE

To present a recommended approach to the problem of "relative" adrenal insufficiency (RAI) in the intensive care unit (ICU).

METHODS

We examine historical data that support the traditional concepts of adrenal insufficiency and the idea that the increase in cortisol secretion during stress is needed to survive the stress. The controversial use of treatment with glucocorticoids (GCs) in patients with sepsis and septic shock in the ICU (and thus survival benefit) is also briefly discussed.

RESULTS

During the past decade, the concept of RAI as the failure of cortisol secretion to increase in response to stress to sustain the patient through that stress has gained strength. In some studies, it has been suggested that as many as 75% of patients in an ICU setting have RAI. Experimental support for the concept is not possible because there is no clinically useful laboratory measure of GC action. Therefore, diagnosis is generally based on interpretation of the cosyntropin stimulation test.

CONCLUSION

The best clinical judgment should always guide interpretation of any test results, and sharp categorization of patients on the basis of a single cutoff criterion should be avoided. Overall, the concept of RAI has no clinical utility. In these cases, administration of GCs adds cost without benefit and with increased risk.

Nonthyroidal illness syndrome in children

Neuroendocrine changes in the hypothalamic-pituitary-thyroid axis during critical illness result in nonthyroidal illness syndrome (NTIS) characterized by abnormal thyrotropin (TSH) and thyroid hormone levels. Studies looking at the natural history of neuroendocrine changes during critical illness have revealed the presence of NTIS. NTIS has been described in a variety of patient settings. Many studies have tried to uncover the pathophysiology behind NTIS and several theories are proposed. Whether NTIS requires treatment or intervention is still controversial and the results of the treatment studies are arguably mixed. Whether implicitly stated or not, the underlying purpose of all the natural history, pathophysiology, or treatment studies is to determine whether NTIS is adaptive or maladaptive. Some studies have illustrated a correlation between illness severity and the degree of NTIS but a cause and effect relationship is still elusive. The human studies can be divided between those with either adult or pediatric subjects, with much less data available in the latter. This review examines the available literature on NTIS with an emphasis on the pediatric literature.

Acute insulin resistance following injury

Hyperglycemia and insulin resistance often occur following injury and/or critical illness. Whereas intensive insulin treatment reduces hyperglycemia, mortality and morbidity in certain patients, little is known regarding the pathophysiology of acute insulin resistance following injury and infection. Studies suggest that acute insulin resistance is complex and might differ in a tissue-specific manner, involving multiple causative factors and intracellular signaling pathways. Therefore, the advantages of intensive insulin therapy might not be uniform to all injuries or critical illnesses. Clearly, the increased incidence of hypoglycemic incidents following intensive insulin therapy indicates a need for understanding the underlying molecular mechanisms of the acute development of insulin resistance, which will allow a more targeted approach to treat altered glucose metabolism of critically ill patients.

Relative adrenal insufficiency

PURPOSE OF REVIEW

This article will review the clinical presentation, diagnosis, and treatment of acute adrenal insufficiency and explore the concept of 'relative adrenal insufficiency' in the critically ill.

RECENT FINDINGS

Current dogma suggests that as many as 70% of patients in intensive care units with the clinical syndromes of sepsis or cardiogenic shock have 'relative adrenal insufficiency'. This article will explore how this concept came into being and why the concept has no clinical utility.

SUMMARY

This article will provide an approach to critically ill patients that will identify adrenal insufficiency when it is part of the pathophysiology of a given patient and, at the same time, prevent the unnecessary treatment of critically ill patients with high doses of glucocorticoids for 'stress' when adrenal insufficiency is not a factor in the illness.

Tissue mRNA expression of the glucocorticoid receptor and its splice variants in fatal critical illness

BACKGROUND

Critical illness results in activation of the hypothalamic-pituitary-adrenal (HPA) axis, which might be accompanied by a peripheral adaptation in glucocorticoid sensitivity. Tissue sensitivity is determined by the active glucocorticoid receptor GRalpha, of which two splice variants involving the hormone-binding domain exist, GRbeta and GR-P.

OBJECTIVE

To study tissue mRNA expression of the GR and its splice variants in fatal critical illness.

DESIGN AND METHODS

We assessed mRNA expression of the GRalpha, GRbeta and GR-P variants in liver (n = 58) and muscle (n = 65) of patients who had died after intensive care, and had been randomized for insulin treatment. We analysed whether GR mRNA expression was associated with insulin treatment, cortisol levels and glucocorticoid treatment.

RESULTS

GRalpha and GR-P mRNA constituted 87 +/- 8% and 13 +/- 2%, respectively, of total GR mRNA in liver. GRbeta mRNA could only be amplified in five liver samples. All variants were present in most muscle samples (alpha = 96 +/- 11%, P = 3.9 +/- 0.4%, beta = 0.010 +/- 0.002%). GR expression was not associated with insulin therapy. A strong positive relationship was observed between the different GR variants in both liver and muscle (P < 0.001 for all). Serum cortisol levels were negatively associated with liver GRalpha and muscle GR-P expression (P < 0.05). mRNA expression of both liver GRalpha and GR-P, but not muscle GR, was substantially lower in patients who had received exogenous glucocorticoids (P < 0.01).

CONCLUSION

We demonstrate the presence of GRalpha and GR-P mRNA in liver and of GRalpha, GRbeta and GR-P mRNA in muscle, with no evidence for altered splicing in critical illness. In contrast to muscle GR, liver GR expression was substantially lower in patients receiving exogenous glucocorticoids.

Tissue-specific difference in the molecular mechanisms for the development of acute insulin resistance after injury

Acute insulin resistance occurs after injury, hemorrhage, infection, and critical illness. However, little is known about the development of this acute insulin-resistant state. In the current study, we found that insulin resistance develops rapidly in skeletal muscle, with the earliest insulin signaling defects at 60 min. However, defects in insulin signaling were measurable even earlier in liver, by as soon as 15 min after hemorrhage. To begin to understand the mechanisms for the development of acute insulin resistance, serine phosphorylation of insulin receptor substrate (IRS)-1 and c-Jun N-terminal kinase phosphorylation/activation was investigated. These markers (and possible contributors) of insulin resistance were increased in the liver after hemorrhage but not measurable in skeletal muscle. Because glucocorticoids are important counterregulatory hormones responsible for glucose homeostasis, a glucocorticoid synthesis inhibitor, metyrapone, and a glucocorticoid receptor antagonist, RU486, were administered to adult rats prior to hemorrhage. In the liver, the defects of insulin signaling after hemorrhage, including reduced tyrosine phosphorylation of the insulin receptor and IRS-1, association between IRS-1 and phosphatidylinositol 3-kinase and serine phosphorylation of Akt in response to insulin were not altered by pretreatment of rats with metyrapone or RU486. In contrast, hemorrhage-induced defects in insulin signaling were dramatically reversed in skeletal muscle, indicating a prevention of insulin resistance in muscle. These results suggest that distinct mechanisms for hemorrhage-induced acute insulin resistance are present in these two tissues and that glucocorticoids are involved in the rapid development of insulin resistance in skeletal muscle, but not in the liver, after hemorrhage.

Predicting a low cortisol response to adrenocorticotrophic hormone in the critically ill: a retrospective cohort study

Introduction

Identification of risk factors for diminished cortisol response to adrenocorticotrophic hormone (ACTH) in the critically ill could facilitate recognition of relative adrenal insufficiency in these patients. Therefore, we studied predictors of a low cortisol response to ACTH.

Methods

A retrospective cohort study was conducted in a general intensive care unit of a university hospital over a three year period. The study included 405 critically ill patients, who underwent a 250 μg ACTH stimulation test because of prolonged hypotension or need for vasopressor/inotropic therapy. Plasma cortisol was measured before and 30 and 60 min after ACTH injection. A low adrenal response was defined as an increase in cortisol of less than 250 nmol/l or a peak cortisol level below 500 nmol/l. Various clinical variables were collected at admission and on the test day.

Results

A low ACTH response occurred in 63% of patients. Predictors, in multivariate analysis, included sepsis at admission, low platelets, low pH and bicarbonate, low albumin levels, high Sequential Organ Failure Assessment score and absence of prior cardiac surgery, and these predictors were independent of baseline cortisol and intubation with etomidate. Baseline cortisol/albumin ratios, as an index of free cortisol, were directly related and increases in cortisol/albumin were inversely related to disease severity indicators such as the Simplified Acute Physiology Score II and Sequential Organ Failure Assessment score (Spearman r = -0.21; P < 0.0001).

Conclusion

In critically ill patients, low pH/bicarbonate and platelet count, greater severity of disease and organ failure are predictors of a low adrenocortical response to ACTH, independent of baseline cortisol values and cortisol binding capacity in blood. These findings may help to delineate relative adrenal insufficiency and suggest that adrenocortical suppression occurs as a result of metabolic acidosis and coagulation disturbances.

Serum cortisol and thyroxine concentrations as predictors of death in critically ill puppies with parvoviral diarrhea

OBJECTIVE

To evaluate the role of adrenal and thyroid hormones in the prediction of death in a population of critically ill puppies with parvoviral diarrhea by measuring serial daily serum concentrations of cortisol and thyroxine.

DESIGN

Prospective case-control study.

ANIMALS

57 critically ill puppies with parvoviral diarrhea admitted to the hospital and 17 clinically normal control puppies.

PROCEDURES

Basal serum cortisol and thyroxine concentrations were measured for each dog with parvoviral diarrhea at admission (prior to treatment) and daily until death, euthanasia, or discharge.

RESULTS

Median time between admission and death was 48 hours (ie, on day 3). Median serum cortisol concentration on day 1 (admission) in all dogs with parvoviral diarrhea (248 nmol/L) was significantly higher than in control dogs (77 nmol/L). No significant difference was found in the day 1 median serum cortisol concentration of 11 dogs that died (302 nmol/L) and 46 dogs that survived (238 nmol/L). A significantly higher median serum cortisol concentration was, however, found in nonsurvivor group dogs, compared with survivor group dogs, on days 2 and 3. Median serum thyroxine concentration on day 1 in dogs with parvoviral diarrhea was significantly lower than in control dogs (8.12 nmol/L vs 35 nmol/L, respectively). Median serum thyroxine concentration of nonsurvivor group dogs (4.4 nmol/L) was significantly lower than that of survivor group dogs (9.2 nmol/L) at admission and became even lower on days 2 and 3.

CONCLUSIONS AND CLINICAL RELEVANCE

High serum cortisol and low serum thyroxine concentrations at 24 and 48 hours after admission were associated with death in dogs with parvoviral diarrhea.

Free and Total Cortisol Levels as Predictors of Severity and Outcome in Community-acquired Pneumonia

RATIONALE

High cortisol levels are of prognostic value in sepsis. The predictive value of cortisol in pneumonia is unknown. Routinely available assays measure serum total cortisol (TC) and not free cortisol (FC). Whether FC concentrations better reflect outcome is uncertain.

OBJECTIVES

To investigate the predictive value of TC and FC in community-acquired pneumonia (CAP).

METHODS

Preplanned subanalysis of a prospective intervention study in 278 patients presenting to the emergency department with CAP.

MEASUREMENTS AND MAIN RESULTS

TC, FC, procalcitonin, C-reactive protein, leukocytes, clinical variables, and the pneumonia severity index (PSI) were measured. The major outcome measures were PSI and survival. TC and FC, but not C-reactive protein or leukocytes, increased with increasing severity of CAP according to the PSI (P < 0.001). TC and FC levels on presentation in patients who died during follow-up were significantly higher as compared with levels in survivors. In a receiver operating characteristic analysis to predict survival, the area under the receiver operating characteristic curve (AUC) was 0.76 (95% confidence interval, 0.70-0.81) for TC and 0.69 (0.63-0.74) for FC. This was similar to the AUC of the PSI (0.76 [0.70-0.81]), and better as compared with C-reactive protein, procalcitonin, or leukocytes. In univariate analysis, only TC, FC, and the PSI were predictors of death. In multivariate analysis, the predictive potential of TC equaled the prognostic power of PSI points.

CONCLUSIONS

Cortisol levels are predictors of severity and outcome in CAP to a similar extent to the PSI, and are better than routinely measured laboratory parameters. In CAP, the prognostic accuracy of FC is not superior to TC. Clinical trial registered with www.controlled-trials.com (ISRCTN04176397).

Endocrine predictors of mortality in canine babesiosis caused by Babesia canis rossi

This prospective, cross-sectional, observational study was designed to determine the association between the hormones of the pituitary-adrenal and pituitary-thyroid axes and outcome in dogs with naturally occurring Babesia canis rossi babesiosis. Ninety-five dogs with canine babesiosis were studied and blood samples were obtained from the jugular vein in each dog prior to treatment at admission to hospital. Serum cortisol, adrenocorticotrophic hormone (ACTH), thyroxine, free thyroxine and thyrotropin (TSH) concentrations were measured. Diagnosis was confirmed by polymerase chain reaction and reverse line blot and dogs infected with Babesia canis vogeli or Ehrlichia canis were excluded. Three outcomes were defined: hospitalization with subsequent death (n=7); hospitalization followed by recovery (n=56); and treatment as an outpatient (n=32). Serum cortisol and ACTH concentrations were significantly higher in the dogs that died, compared to hospitalized dogs that survived and compared to dogs treated as outpatients. Serum T4 and free T4 concentrations were significantly lower in the dogs that died, compared to the hospitalized dogs that survived and compared to dogs treated as outpatients. Serum TSH concentrations were not significantly different between any of the groups. Mortality was significantly associated with high cortisol and high ACTH concentrations and with low T4 and fT4 concentrations in dogs suffering from B. canis rossi babesiosis.

Adrenal response in patients with septic shock of abdominal origin: relationship to survival

OBJECTIVE

To evaluate the prognostic value of adrenocortical response to corticotropin in septic shock patients operated on exclusively for an intra-abdominal source of infection.

DESIGN AND SETTING

Prospective, observational, single-center study in a surgical intensive care unit of a university hospital

PATIENTS

118 consecutive septic shock patients undergoing laparotomy or drainage for intra-abdominal infection.

MEASUREMENTS AND RESULTS

Baseline cortisol (t (0)) and cortisol response to corticotropin test (Delta) were measured during the first 24 h following onset of shock. The relationship between adrenal function test results and survival was analyzed as well as the effect of etomidate anesthesia. Cortisol plasma level at t (0) was higher in nonsurvivors than in survivors (33 +/- 23 vs. 25 +/- 14 microg/dl), but the response to corticotropin test did not differ between these two subgroups. ROC analysis showed threshold values for t (0) (32 microg/dl) and Delta (8 microg/dl) that best discriminated survivors from nonsurvivors in our population. We observed no difference in survival at the end of hospital stay using log rank test when patients were separated according to t (0), Delta, or both. In addition, adrenal function tests and survival did not differ in patients who received etomidate anesthesia (n = 69) during the surgical treatment of their abdominal sepsis.

CONCLUSIONS

In this cohort of patients with abdominal septic shock baseline cortisol level and the response to corticotropin test did not discriminate survivors from nonsurvivors. No deleterious impact of etomidate anesthesia on adrenal function tests and survival was observed in these patients.

Adrenal dysfunction in critical illness: a clinical entity that requires treatment?

Corticosteroids are of key importance in controlling the immune system and in the maintenance of cardiovascular function. Thus, an adequate function of the adrenal cortex is essential for survival in critical illness. There is growing evidence that adrenocortical function can become impaired during critical illness, because of deleterious effects of cytokines, leading to a state of relative adrenal dysfunction. Under these circumstances, administration of corticosteroids is necessary for recovery of the patient. How such a state of adrenal dysfunction should be detected is still not clear, however, making it difficult to decide when to administer corticosteroids and to which patients.

Relative adrenal insufficiency: an identifiable entity in nonseptic critically ill patients?

OBJECTIVE

To determine whether relative adrenal insufficiency (RAI) can be identified in nonseptic hypotensive patients in the intensive care unit (ICU).

DESIGN

Retrospective study in a medical-surgical ICU of a university hospital.

PATIENTS

One hundred and seventy-two nonseptic ICU patients (51% after trauma or surgery), who underwent a short 250 microg ACTH test because of > 6 h hypotension or vasopressor/inotropic therapy.

MEASUREMENTS

On the test day, the Simplified Acute Physiology Score II (SAPS II) and Sequential Organ Failure Assessment (SOFA) score were calculated to estimate disease severity. The ICU mortality until day 28 was recorded. Best discriminative levels of baseline cortisol, increases and peaks were established using receiver operating characteristic curves. These and corticosteroid treatment (in n = 112, 65%), among other variables, were examined by multiple logistic regression and Cox proportional hazard regression analyses to find independent predictors of ICU mortality until day 28.

RESULTS

ICU mortality until day 28 was 23%. Nonsurvivors had higher SAPS II and SOFA scores. Baseline cortisol levels correlated directly with albumin levels and SAPS II. In the multivariate analyses, a cortisol baseline > 475 nmol/l and cortisol increase < 200 nmol/l predicted mortality, largely dependent on disease severity but independent of albumin levels. Corticosteroid (hydrocortisone) treatment was not associated with an improved outcome, regardless of the ACTH test results.

CONCLUSION

In nonseptic hypotensive ICU patients, a low cortisol/ACTH response and treatment with corticosteroids do not contribute to mortality prediction by severity of disease. The data thus argue against RAI identifiable by cortisol/ACTH testing and necessitating corticosteroid substitution treatment in these patients.

[The euthyroid sick syndrome in severe acute illness]

OBJECTIVE

To describe euthyroid sick syndrome (ESS) and its different clinical variants in severe acute illness.

DESIGN

This prospective cohort study examined hormone results and outcome for patients admitted to our intensive care unit (ICU).

METHODS

In this heterogeneous group of 108 patients from our ICU we analyzed the prevalence of ESS and its influence on mortality and sought to determine if any thyroid indicators had a prognostic value.

RESULTS

The prevalence of ESS was similar to that described by other authors (68.5% for ESS type I, 15.7% for type II and 1.9% for type III). Patients developed thyroid alterations on their third day of hospitalization and those with ESS type II had a higher mortality rate. The only thyroid indicator with prognostic value was a reverse triiodothyronine (rT3) value exceeding 0.61 ng/mL.

CONCLUSION

Severe acute illness induced the thyroid alterations known as ESS. Type I had the highest prevalence, but type II was correlated with a higher mortality rate. The only thyroid indicator with a prognostic value was rT3.

The dynamic neuroendocrine response to critical illness

The severity of striking alterations in the hypothalamic-anterior pituitary-peripheral hormone axes, which are the hallmark of severity of critical illness, is associated with a high risk for morbidity and mortality. Most attempts to correct the hormone balance are ineffective or harmful because of lack of pathophysiologic understanding. Extensive research has provided more insight in the biphasic neuroendocrine response to critical illness: the acute phase is characterized by an actively secreting pituitary but low peripheral effector hormone levels. In contrast, in prolonged critical illness, uniform suppression of the neuroendocrine axes, predominantly of hypothalamic origin, contributes to low serum levels of the respective target-organ hormones.

Endocrine aspects of acute and prolonged critical illness

Critical illness is characterized by striking alterations in the hypothalamic-anterior-pituitary-peripheral-hormone axes, the severity of which is associated with a high risk of morbidity and mortality. Most attempts to correct hormone balance have been shown ineffective or even harmful because of a lack of pathophysiologic insight. There is a biphasic (neuro)endocrine response to critical illness. The acute phase is characterized by an actively secreting pituitary, but the concentrations of most peripheral effector hormones are low, partly due to the development of target-organ resistance. In contrast, in prolonged critical illness, uniform (predominantly hypothalamic) suppression of the (neuro)endocrine axes contributes to the low serum levels of the respective target-organ hormones. The adaptations in the acute phase are considered to be beneficial for short-term survival. In the chronic phase, however, the observed (neuro)endocrine alterations appear to contribute to the general wasting syndrome. With the exception of intensive insulin therapy, and perhaps hydrocortisone administration for a subgroup of patients, no hormonal intervention has proven to beneficially affect outcome. The combined administration of hypothalamic releasing factors does, however, hold promise as a safe therapy to reverse the (neuro)endocrine and metabolic abnormalities of prolonged critical illness by concomitant reactivation of the different anterior-pituitary axes.

Differential effects of a perioperative hyperinsulinemic normoglycemic clamp on the neurohumoral stress response during coronary artery surgery

BACKGROUND

Hyperglycemia in patients undergoing coronary artery bypass grafting (CABG) is associated with adverse outcome. Although insulin infusion strategies are increasingly used to improve outcome, a pathophysiological rationale is currently lacking. The present study was designed to quantify the effects of a perioperative hyperinsulinemic normoglycemic clamp on the neurohumoral stress response during CABG.

METHODS

Forty-four nondiabetic patients, scheduled for elective CABG, were randomized to either a control group (n = 22) receiving standard care or to a clamp group (n = 22) receiving additionally a perioperative hyperinsulinemic (regular insulin at a fixed rate of 0.1 IU.kg(-1).h(-1)) normoglycemic (plasma glucose between 3.0 and 6.0 mmol.liter(-1)) clamp during 26 h. We measured the endocrine response of the hypothalamus-pituitary-adrenal (HPA) axis, the sympathoadrenal axis, and glucagon, as well as plasma glucose and insulin at regular intervals from the induction of anesthesia at baseline through the end of the second postoperative day (POD).

RESULTS

There were no differences in clinical outcome between the groups. In the control group, hyperglycemia developed at the end of surgery and remained present until the final measurement point on POD2, whereas plasma insulin levels remained unchanged until the morning of POD1. In the intervention group, normoglycemia was well maintained during the clamp, whereas insulin levels ranged between 600 and 800 pmol.liter(-1). In both groups, plasma ACTH and cortisol increased from 6 h after discontinuation of cardiopulmonary bypass onward. However, during the clamp period, a marked reduction in the HPA axis response was found in the intervention group, as reflected by a 47% smaller increase in area under the curve in plasma ACTH (P = 0.035) and a 27% smaller increase in plasma cortisol (P = 0.002) compared with the control group. Compared with baseline, epinephrine and norepinephrine increased by the end of the clamp interval until POD2 in both groups. Surprisingly, the area under the curve of epinephrine levels was 47% higher (P = 0.026) after the clamp interval in the intervention group as compared with the control group.

CONCLUSION

A hyperinsulinemic normoglycemic clamp during CABG delays and attenuates the HPA axis response during the first 18 h of the myocardial reperfusion period, whereas after the clamp, plasma epinephrine is higher. The impact of delaying cortisol responses on clinical outcome of CABG remains to be elucidated.

Hypothalamic pituitary adrenal function during critical illness: limitations of current assessment methods

CONTEXT

Activation of the hypothalamic-pituitary-adrenal (HPA) axis represents one of several important responses to stressful events and critical illnesses. Despite a large volume of published data, several controversies continue to be debated, such as the definition of normal adrenal response, the concept of relative adrenal insufficiency, and the use of glucocorticoids in the setting of critical illness.

OBJECTIVES

The primary objective was to review some of the modulating factors and limitations of currently used methods of assessing HPA function during critical illness and provide alternative approaches in that setting.

DESIGN

This was a critical review of relevant data from the literature with inclusion of previously published as well as unpublished observations by the author. Data on HPA function during three different forms of critical illnesses were reviewed: experimental endotoxemia in healthy volunteers, the response to major surgical procedures in patients with normal HPA, and the spontaneous acute to subacute critical illnesses observed in patients treated in intensive care units.

SETTING

The study was conducted at an academic medical center.

PATIENTS/PARTICIPANTS

Participants were critically ill subjects.

INTERVENTION

There was no intervention.

MAIN OUTCOME MEASURE

The main measure was to provide data on the superiority of measuring serum free cortisol during critical illness as contrasted to those of total cortisol measurements.

RESULTS

Serum free cortisol measurement is the most reliable method to assess adrenal function in critically ill, hypoproteinemic patients. A random serum free cortisol is expected to be 1.8 microg/dl or more in most critically ill patients, irrespective of their serum binding proteins. Because the free cortisol assay is not currently available for routine clinical use, alternative approaches to estimate serum free cortisol can be used. These include calculated free cortisol (Coolens' method) and determining the free cortisol index (ratio of serum cortisol to transcortin concentrations). Preliminary data suggest that salivary cortisol measurements might be another alternative approach to estimating the free cortisol in the circulation. When serum binding proteins (albumin, transcortin) are near normal, measurements of total serum cortisol continue to provide reliable assessment of adrenal function in critically ill patients, in whom a random serum total cortisol would be expected to be 15 microg/dl or more in most patients. In hypoproteinemic critically ill subjects, a random serum total cortisol level is expected to be 9.5 microg/dl or more in most patients. Data on Cosyntropin-stimulated serum total and free cortisol levels should be interpreted with the understanding that the responses in critically ill subjects are higher than those of healthy ambulatory volunteers. The Cosyntropin-induced increment in serum total cortisol should not be used as a criterion for defining adrenal function, especially in critically ill patients.

CONCLUSIONS

The routine use of glucocorticoids during critical illness is not justified except in patients in whom adrenal insufficiency was properly diagnosed or others who are hypotensive, septic, and unresponsive to standard therapy. When glucocorticoids are used, hydrocortisone should be the drug of choice and should be given at the lowest dose and for the shortest duration possible. The hydrocortisone dose (50 mg every 6 h) that is mistakenly labeled as low-dose hydrocortisone leads to excessive elevation in serum cortisol to values severalfold greater than those achieved in patients with documented normal adrenal function. The latter data should call into question the current practice of using such doses of hydrocortisone even in the adrenally insufficient subjects.

Do we have reliable biochemical markers to predict the outcome of critical illness?

Current outcome prediction in critically ill patients relies on the art of clinical judgement and/or the science of prognostication using illness severity scores. The biochemical processes underlying critical illness have increasingly been unravelled. Several biochemical markers reflecting the process of inflammation, immune dysfunction, impaired tissue oxygenation and endocrine alterations have been evaluated for their predictive power in small subpopulations of critically ill patients. However, none of these parameters has been validated in large populations of unselected ICU patients as has been done for the illness severity and organ failure scores. A simple biochemical predictor of ICU mortality will probably remain elusive because the processes underlying critical illness are very complex and heterogeneous. Future prognostic models will need to be far more sophisticated.

Endocrine markers of severity and prognosis in critical illness

The cellular processes that unfold in critical illness involve a variety of circulating substances, that may provide clinically relevant insight into the severity and outcome. Among hormonal markers, cortisol, several thyroid-related substances, as well as natriuretic peptides are discussed in this review. Glucose and lipids constitute metabolic markers, the identification and treatment of the former has been of particular importance. Among immune markers, both proinflammatory and anti-inflammatory cytokines, such as interleukin-6, contribute essential prognostic information. Finally, the complement and coagulation pathways also provide unique insight into this complex and heterogeneous process.

Relative adrenal insufficiency among trauma patients in a community hospital

BACKGROUND

The integrity of the hypothalamic-pituitary-adrenal (HPA) axis is a major determinant of the host response to stress. Recent studies have proven that low doses of hydrocortisone and fludrocortisone can significantly reduce mortality in patients with relative adrenal insufficiency (RAI) without increasing adverse events.

STUDY DESIGN

This study was a retrospective chart review of patients in a community hospital who carried the diagnosis of both adrenal insufficiency and trauma.

RESULTS

Over a 16-month period, the incidence of RAI among severely injured patients (injury severity score >/= 13) was 3%. Only 1 patient had the classic electrolyte findings of adrenal insufficiency, but all had vasopressor-dependent hypotension. Our patients had an average intensive care unit day stay of 37 days and were not tested for RAI on average until day 20 of their intensive care unit stay. Random cortisol levels did not correlate with injury severity. Six patients (75%) had a positive hemodynamic response to steroids.

CONCLUSIONS

Relative adrenal insufficiency after trauma is rare. In RAI, clear signs and symptoms are usually absent. The clinical diagnostic clue may be the unexplained hypotension and the resistance to inappropriately high doses of inotropes and vasoactive agents. The hemodynamic profile often shows a hyperdynamic state of high cardiac output and a low systemic vascular resistance. Baseline serum cortisol levels did not correlate with injury severity scores in this group of patients, which suggests a defect in the HPA axis. An intensive care unit day stay of greater than or equal to 20 days, ventilator dependence/acute respiratory distress syndrome, and a hyperdynamic state mandates consideration of endocrine testing to exclude RAI. Physiologic doses of hydrocortisone can reverse this potentially life-threatening syndrome.

The Neuroendocrine Response to Critical Illness is a Dynamic Process

Striking alterations in the hypothalamic-anterior pituitary-peripheral hormone axes hallmark the state of critical illness, their severity being associated with high risk for morbidity and mortality. Early endocrine intervention strategies aimed to correct the hormone balance have been shown ineffective or even harmful because of lack of thorough pathophysiologic understanding of these neuroendocrine changes. Extensive research, however, has provided crucial insights, with the demonstration of the biphasic response of the anterior pituitary to the severe stress of critical illness.

Clinical evaluation of hormonal stress state in medical ICU patients: a prospective blinded observational study

OBJECTIVE

To evaluate whether classification of patients as having low, moderate, or high stress based on clinical parameters is associated with plasma levels of stress hormone.

DESIGN AND SETTING

Prospective, blinded, observational study in an 18-bed medical ICU.

PATIENTS

Eighty-eight consecutive patients.

INTERVENTIONS

Patients were classified as low (n=28), moderate (n=33) or high stress (n=27) on days 0 and 3 of ICU stay, based on 1 point for each abnormal parameter: body temperature, heart rate, systemic arterial pressure, respiratory rate, physical agitation, presence of infection and catecholamine administration. The stress categories were: high: 4 points or more, moderate 2-3 points, low 1 point. Plasma growth hormone (GH), insulin-like growth factor 1 (IGF-1), insulin, glucagon, cortisol were measured on days 0 and 3.

MEASUREMENTS AND RESULTS

Plasma cortisol and glucagon were significantly higher and IGF-1 lower in high vs. low stress patients on days 0 and 3. High stress patients were more likely to have high cortisol levels (odds ratio 5.8, confidence interval 1.8-18.9), high glucagon (8.7, 2.1-36.1), and low IGF-1 levels (5.9, 1.8-19.0) than low stress patients on day 0. Moderate stress patients were also more likely to have high cortisol and glucagon levels than low stress patients. Insulin and GH did not differ significantly. Results were similar for day 3.

CONCLUSIONS

Moderate and severe stress was significantly associated with high catabolic (cortisol, glucagon) and low anabolic (IGF-1) hormone levels. The hormonal stress level in ICU patients can be estimated from simple clinical parameters during routine clinical evaluation.

Cortisol changes among patients with septic shock and the relationship to ICU and hospital stay

OBJECTIVE

To evaluate adrenal function in patients with severe sepsis or septic shock.

DESIGN

A prospective study of unstimulated and high-dose ACTH stimulated cortisol levels on days 1 and 2 following ICU admission and day 28 or last day of hospitalization (herein day 28).

SETTING

General intensive care unit.

PATIENTS

34 septic patients.

INTERVENTIONS

On days 1, 2, and 28 of sepsis unstimulated and ACTH stimulated cortisol levels were evaluated. End-points were length of ICU and hospital stay and 28 day all cause mortality.

MEASUREMENTS AND RESULTS

Eight patients on days 1 and 2 had criteria of adrenal insufficiency defined as unstimulated cortisol levels less than 15 microg/dl. Patients with unstimulated cortisol levels less than 15 microg/dl on day 1 or change of 9 microg/dl or less had longer ICU stays. Patients with unstimulated cortisol levels less than 15 microg/dl on day 1 also demonstrated longer hospital stay. On day 1 regression analysis revealed that unstimulated cortisol levels had a significant inverse correlation with length of ICU and hospital stay. The proportional change between unstimulated cortisol and post-ACTH cortisol (Delta%) is a new modality; the higher this Delta% value, the longer is the patient's ICU and hospital stay. A significant positive correlation was found in survivors when comparing unstimulated cortisol vs. day 28 changes.

CONCLUSIONS

The present study highlights the wide range of cortisol levels among patients with sepsis. We observed a difference in cortisol response pattern between survivors and nonsurvivors on day 28. The proportional change between unstimulated cortisol and post-ACTH cortisol was used as a method to evaluate the relative change in cortisol levels between patients.

Thyroid hormone levels improve the prediction of mortality among patients admitted to the intensive care unit

OBJECTIVE

As hormones are strongly associated with mortality in critically ill patients, we investigated whether mortality prediction based on the Acute Physiology and Chronic Health Evaluation (APACHE) is improved by combining this score with hormone measurements.

DESIGN AND SETTING

Intensive care units in three hospitals.

PATIENTS AND PARTICIPANTS

113 patients admitted to.

MEASUREMENTS

Within the first hour after ICU admission we measured total triiodothyronine, total thyroxine, free thyroxine, thyrotropin, cortisol, growth hormone, dehydroepiandrosterone, and prolactin levels and administered the APACHE. Patients were followed until they died or were discharged from the ICU.

RESULTS

The best logistic regression model for ICU mortality included the APACHE score and thyroid-stimulating hormone and triiodothyronine levels. This model had an area under the receiver operating characteristic curve of 0.88, significantly higher than the APACHE score alone with 0.75. The model with hormone levels and APACHE score was also significantly better calibrated than the model with only the APACHE score.

CONCLUSIONS

The addition of thyroid hormones to the APACHE score improves the prediction of mortality for ICU patients.

Leptin ameliorates burn-induced multiple organ damage and modulates postburn immune response in rats

The present study was designed to determine whether exogenous leptin reduces remote organ injury in the rats with thermal burn trauma. Leptin (10 microg/kg) or saline was administered intraperitoneally after burn injury, and the rats were decapitated at either 6 or 24 h. Plasma samples of 24-h burn group were assayed for the determination of monocyte and neutrophil apoptosis. Thermal injury increased tissue-associated myeloperoxidase (MPO) activity and microscopic damage scores in the lung, liver, stomach, colon and kidney of both 6- and 24-h burn groups. In the 6-h burn group, leptin reduced microscopic damage score in the liver and kidney only, while damage scores in the 24-h burn group were reduced in all the tissues except the lung. Also, in both burn groups, leptin reduced elevated MPO activity in all tissues except the lung. The percentage of mononuclear cells was significantly reduced at the 24 h of burn injury, while the granulocyte percentage was increased. Leptin treatment, however, had no significant effect on burn-induced reversal of white blood cell ratios. On the other hand, burn-induced increase in the death of mononuclear cells and granulocytes was significantly reduced in leptin-treated rats. The results of the present study suggest that leptin may provide a therapeutic benefit in diminishing burn-induced inflammation and associated multiple organ failure.