Dopamine and the sick euthyroid syndrome in critical illness

Different subtypes of nonthyroidal illness syndrome on the prognosis of septic patients: a two-centered retrospective cohort study

Background

Nonthyroidal illness syndrome (NTIS) is a common endocrine dysfunction predicting unfavorable outcomes in critical illness. The objective of the study is to evaluate the association between different NTIS subtypes with outcomes in septic patients.

Methods

Septic patients in two Chinese academic centers from October 2012 and October 2022 are enrolled in analysis. Multivariable regressions are used to assess associations between NTIS and outcomes. Outcomes include in-hospital mortality, length of stay in hospital (LOS), non-invasive ventilation failure and weaning failure. Patients with NTIS are categorized into 4 types according to the different levels of FT4 and TSH. The association between different NTIS subtypes and mortality are further analyzed. Survival curve is plotted using the Kaplan-Meier method.

Results

After screening, a total of 1226 septic patients with complete thyroid hormones result are eventually enrolled. Among them, 520 (42.4%) patients are diagnosed as NTIS. In multivariable regression analysis, NTIS is independently associated with increased 30-days mortality (OR=1.759, CI 1.009-3.104, p=0.047), but has no association with 60-days mortality (OR=1.524, CI 0.893-2.618, p=0.123), 90-days mortality (OR=1.411, CI 0.831-2.408, p=0.203), LOS, non-invasive ventilation failure or weaning failure. In NTIS subtypes, NTIS patients with low FT3 and TSH levels, regardless of the FT4 values, have significantly higher mortality than euthyroid patients (30-days mortality, OR= 6.488, CI 1.546-27.808, p=0.01; 60-days mortality, OR=3.973, CI 1.006-15.579, p=0.046; 90-days mortality, OR=3.849, CI 0.977-15.088, p=0.051). This result is consistent in patients with low FT3 and FT4 levels, regardless of the TSH values (30-days mortality, OR=3.349, CI 1.402-7.957, p=0.006; 60-days mortality, OR= 2.594, CI 1.122-5.930, p=0.024; 90-days mortality, OR=2.55, CI 1.110-5.804, p=0.025). There is no survival difference between NTIS patients with low FT3 only and euthyroid patients. Survival plot shows the worst prognosis is in NTIS patients with low FT3, FT4 and TSH level.

Conclusions

NTIS is frequent in sepsis. A reduction of FT3 together with FT4 or TSH, but not FT3 only, is associated with an increased risk of mortality.

Prognostic significance of thyroid hormone T3 in patients with septic shock: a retrospective cohort study

Background

The role of thyroid hormones is crucial in the response to stress and critical illness, which has been reported to be closely associated with a poor prognosis in patients admitted to the intensive care unit (ICU). This study aimed to explore the relationship between thyroid hormone and prognosis in septic shock patients.

Methods

A total of 186 patients with septic shock were enrolled in the analytical study between December 2014 and September 2022. The baseline variables and thyroid hormone were collected. The patients were divided into survivor group and non-survivor group according to whether they died during the ICU hospitalization. Among 186 patients with septic shock, 123 (66.13%) were in the survivor group and 63 (33.87%) were in the non-survivor group.

Results

There were significant differences in the indictors of free triiodothyronine (FT3) (p = 0.000), triiodothyronine (T3) (p = 0.000), T3/FT3 (p = 0.000), acute physiology and chronic health evaluation II score (APACHE II) (p = 0.000), sequential organ failure assessment score (SOFA) (p = 0.000), pulse rate (p = 0.020), creatinine (p = 0.008), PaO2/FiO2 (p = 0.000), length of stay (p = 0.000) and hospitalization expenses (p = 0.000) in ICU between the two groups. FT3 [odds ratio (OR): 1.062, 95% confidence interval(CI): (0.021, 0.447), p = 0.003], T3 (OR: 0.291, 95% CI: 0.172-0.975, p = 0.037) and T3/FT3 (OR: 0.985, 95% CI:0.974-0.996, p = 0.006) were independent risk factors of the short-term prognosis of septic shock patients after adjustment. The areas under the receiver operating characteristic curves for T3 was associated with ICU mortality (AUC = 0.796, p < 0.05) and was higher than that for FT3 (AUC = 0.670, p < 0.05) and T3/FT3 (AUC = 0.712, p < 0.05). A Kaplan-Meier curve showed that patients with T3 greater than 0.48 nmol/L had a significantly higher survival rate than the patients with T3 less than 0.48 nmol/L.

Conclusions

The decrease in serum level of T3 in patients with septic shock is associated with ICU mortality. Early detection of serum T3 level could help clinicians to identify septic shock patients at high risk of clinical deterioration.

An Overview on Different L-Thyroxine (l-T4) Formulations and Factors Potentially Influencing the Treatment of Congenital Hypothyroidism During the First 3 Years of Life

Congenital hypothyroidism (CH) is a relatively frequent congenital endocrine disorder, caused by defective production of thyroid hormones (THs) at birth. Because THs are essential for the development of normal neuronal networks, CH is also a common preventable cause of irreversible intellectual disability (ID) in children. Prolonged hypothyroidism, particularly during the THs-dependent processes of brain development in the first years of life, due to delays in diagnosis, inadequate timing and dosing of levothyroxine (l-thyroxine or l-T₄), the non-compliance of families, incorrect follow-up and the interference of foods, drugs and medications affecting the absorption of l-T₄, may be responsible for more severe ID. In this review we evaluate the main factors influencing levels of THs and the absorption of l-T₄ in order to provide a practical guide, based on the existing literature, to allow optimal follow-up for these patients.

Endocrine interventions in the intensive care unit

Following the onset of any life-threatening illness that requires intensive medical care, alterations within the neuroendocrine axes occur which are thought to be essential for survival, as they postpone energy-consuming anabolism, activate energy-producing catabolic pathways, and optimize immunological and cardiovascular functions. The hormonal changes present in the acute phase of critical illness at least partially resemble those of the fasting state, and recent evidence suggests that they are part of a beneficial, evolutionary-conserved adaptive stress response. However, a fraction of patients who survive the acute phase of critical illness remain dependent on vital organ support and enter the prolonged phase of critical illness. In these patients, the hypothalamic-pituitary-peripheral axes are functionally suppressed, which may have negative consequences by which recovery may be hampered and the risk of morbidity and mortality in the long-term increased. Most randomized controlled trials of critically ill patients that investigated the impact on the outcome of treatment with peripheral hormones did not reveal a robust morbidity or mortality benefit. In contrast, small studies of patients in the prolonged phase of critical illness documented promising results with the infusion of hypothalamic-releasing hormones. The currently available data corroborate the need for well-designed and adequately powered RCTs to further investigate the impact of these releasing factors on patient-centered outcomes.

Anterior pituitary function in critical illness

Critical illness is hallmarked by major changes in all hypothalamic-pituitary-peripheral hormonal axes. Extensive animal and human studies have identified a biphasic pattern in circulating pituitary and peripheral hormone levels throughout critical illness by analogy with the fasting state. In the acute phase of critical illness, following a deleterious event, rapid neuroendocrine changes try to direct the human body toward a catabolic state to ensure provision of elementary energy sources, whereas costly anabolic processes are postponed. Thanks to new technologies and improvements in critical care, the majority of patients survive the acute insult and recover within a week. However, an important part of patients admitted to the ICU fail to recover sufficiently, and a prolonged phase of critical illness sets in. This prolonged phase of critical illness is characterized by a uniform suppression of the hypothalamic-pituitary-peripheral hormonal axes. Whereas the alterations in hormonal levels during the first hours and days after the onset of critical illness are evolutionary selected and are likely beneficial for survival, endocrine changes in prolonged critically ill patients could be harmful and may hamper recovery. Most studies investigating the substitution of peripheral hormones or strategies to overcome resistance to anabolic stimuli failed to show benefit for morbidity and mortality. Research on treatment with selected and combined hypothalamic hormones has shown promising results. Well-controlled RCTs to corroborate these findings are needed.

Less known aspects of central hypothyroidism: Part 1 - Acquired etiologies

Central hypothyroidism (CH) is a rare cause of hypothyroidism. CH is frequently overlooked, as its clinical picture is subtle and includes non-specific symptoms; furthermore, if measurement of TSH alone is used to screen for thyroid function, TSH concentrations can be normal or even above the upper normal reference limit. Indeed, certain patients are at risk of developing CH, such as those with a pituitary adenoma or hypophysitis, those who have been treated for a childhood malignancy, have suffered a head trauma, sub-arachnoid hemorrhage or meningitis, and those who are on drugs capable to reduce TSH secretion.

The Impact of l-Thyroxine Treatment of Donors and Recipients on Postoperative Outcomes After Heart Transplantation

OBJECTIVE

The effect of thyroid dysfunction on adverse outcomes has been studied in many different patient populations. The objective of this study was to investigate the effect of thyroid hormone supplementation of donors and recipients on postoperative outcomes after orthotopic heart transplantation.

DESIGN

Retrospective.

SETTING

Single center, university hospital.

PARTICIPANTS

Two-hundred and sixty-six consecutive patients undergoing heart transplantation.

INTERVENTIONS

No interventions.

MEASUREMENTS AND MAIN RESULTS

Demographic, hemodynamic, and clinical characteristics; donor and recipient United Network for Organ Sharing scores; and information on thyroid hormone support of donors and recipients were recorded. During the median follow-up of 4.59 years (interquartile range 4.26-4.92 y), 70 patients (26.3%) died. After adjustments were made for the United Network for Organ Sharing score, recipients who were treated preoperatively with l-thyroxine had a lower risk for all-cause mortality (adjusted hazard ratio [HR] 0.24, 95% confidence interval [CI] 0.06-0.98; p = 0.047) compared with recipients who were not treated with l-thyroxine. In addition, l-thyroxine treatment of donors was associated with a better recipient survival (HR 0.31, 95% CI 0.11-0.87; p = 0.025).

CONCLUSIONS

Pretransplantation thyroid hormone supplementation of donors and recipients was associated with improved long-term survival after heart transplantation.

Clinical characteristics and outcomes of myxedema coma: Analysis of a national inpatient database in Japan

BACKGROUND

Myxedema coma is a life-threatening and emergency presentation of hypothyroidism. However, the clinical features and outcomes of this condition have been poorly defined because of its rarity.

METHODS

We conducted a retrospective observational study of patients diagnosed with myxedema coma from July 2010 through March 2013 using a national inpatient database in Japan. We investigated characteristics, comorbidities, treatments, and in-hospital mortality of patients with myxedema coma.

RESULTS

We identified 149 patients diagnosed with myxedema coma out of approximately 19 million inpatients in the database. The mean (standard deviation) age was 77 (12) years, and two-thirds of the patients were female. The overall proportion of in-hospital mortality among cases was 29.5%. The number of patients was highest in the winter season. Patients treated with steroids, catecholamines, or mechanical ventilation showed higher in-hospital mortality than those without. Variations in type and dosage of thyroid hormone replacement were not associated with in-hospital mortality. The most common comorbidity was cardiovascular diseases (40.3%). The estimated incidence of myxedema coma was 1.08 per million people per year in Japan. Multivariable logistic regression analysis revealed that higher age and use of catecholamines (with or without steroids) were significantly associated with higher in-hospital mortality.

CONCLUSIONS

The present study identified the clinical characteristics and outcomes of patients with myxedema coma using a large-scale database. Myxedema coma mortality was independently associated with age and severe conditions requiring treatment with catecholamines.

Euthyroid Sick Syndrome

In this review, we discuss the characteristics, pathophysiology, and therapeutic implications of the euthyroid sick syndrome. Multiple mechanisms have been identified to contribute to the development of euthyroid sick syndrome, including alterations in the iodothyronine deiodinases, thyroid-stimulating hormone secretion, thyroid hormone binding to plasma protein, transport of thyroid hormone in peripheral tissues, and thyroid hormone receptor activity. The euthyroid sick syndrome appears to be a complex mix of physiologic adaptation and pathologic response to acute illness. The underlying cause for these alterations has not yet been elucidated. Treatment of the euthyroid sick syndrome with thyroid hormone to restore normal serum thyroid hormone levels in an effort to improve disease prognosis and outcomes continues to be a focus of many clinical studies, although currently available data do not provide evidence of a clear benefit of treatment.

Low T3 syndrome is a strong predictor of poor outcomes in patients with community-acquired pneumonia

Low T3 syndrome was previously reported to be linked to poor clinical outcomes in critically ill patients. The aim of this study was to evaluate the predictive power of low T3 syndrome for clinical outcomes in patients with community-acquired pneumonia (CAP). Data for 503 patients were analyzed retrospectively, and the primary end point was 30-day mortality. The intensive care unit (ICU) admission rate and 30-day mortality were 8.3% and 6.4% respectively. The prevalence of low T3 syndrome differed significantly between survivors and nonsurvivors (29.1% vs 71.9%, P < 0.001), and low T3 syndrome was associated with a remarkable increased risk of 30-day mortality and ICU admission in patients with severe CAP. Multivariate logistic regression analysis produced an odds ratio of 2.96 (95% CI 1.14–7.76, P = 0.025) for 30-day mortality in CAP patients with low T3 syndrome. Survival analysis revealed that the survival rate among CAP patients with low T3 syndrome was lower than that in the control group (P < 0.01). Adding low T3 syndrome to the PSI and CURB-65 significantly increased the areas under the ROC curves for predicting ICU admission and 30-day mortality. In conclusion, low T3 syndrome is an independent risk factor for 30-day mortality in CAP patients.

Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement

BACKGROUND

A number of recent advances in our understanding of thyroid physiology may shed light on why some patients feel unwell while taking levothyroxine monotherapy. The purpose of this task force was to review the goals of levothyroxine therapy, the optimal prescription of conventional levothyroxine therapy, the sources of dissatisfaction with levothyroxine therapy, the evidence on treatment alternatives, and the relevant knowledge gaps. We wished to determine whether there are sufficient new data generated by well-designed studies to provide reason to pursue such therapies and change the current standard of care. This document is intended to inform clinical decision-making on thyroid hormone replacement therapy; it is not a replacement for individualized clinical judgment.

METHODS

Task force members identified 24 questions relevant to the treatment of hypothyroidism. The clinical literature relating to each question was then reviewed. Clinical reviews were supplemented, when relevant, with related mechanistic and bench research literature reviews, performed by our team of translational scientists. Ethics reviews were provided, when relevant, by a bioethicist. The responses to questions were formatted, when possible, in the form of a formal clinical recommendation statement. When responses were not suitable for a formal clinical recommendation, a summary response statement without a formal clinical recommendation was developed. For clinical recommendations, the supporting evidence was appraised, and the strength of each clinical recommendation was assessed, using the American College of Physicians system. The final document was organized so that each topic is introduced with a question, followed by a formal clinical recommendation. Stakeholder input was received at a national meeting, with some subsequent refinement of the clinical questions addressed in the document. Consensus was achieved for all recommendations by the task force.

RESULTS

We reviewed the following therapeutic categories: (i) levothyroxine therapy, (ii) non-levothyroxine-based thyroid hormone therapies, and (iii) use of thyroid hormone analogs. The second category included thyroid extracts, synthetic combination therapy, triiodothyronine therapy, and compounded thyroid hormones.

CONCLUSIONS

We concluded that levothyroxine should remain the standard of care for treating hypothyroidism. We found no consistently strong evidence for the superiority of alternative preparations (e.g., levothyroxine-liothyronine combination therapy, or thyroid extract therapy, or others) over monotherapy with levothyroxine, in improving health outcomes. Some examples of future research needs include the development of superior biomarkers of euthyroidism to supplement thyrotropin measurements, mechanistic research on serum triiodothyronine levels (including effects of age and disease status, relationship with tissue concentrations, as well as potential therapeutic targeting), and long-term outcome clinical trials testing combination therapy or thyroid extracts (including subgroup effects). Additional research is also needed to develop thyroid hormone analogs with a favorable benefit to risk profile.

Non-thyroidal illness in the ICU: a syndrome with different faces

BACKGROUND

Critically ill patients typically present with low or low-normal plasma thyroxine, low plasma triiodothyronine (T3), increased plasma reverse T3 (rT3) concentrations, in the absence of a rise in thyrotropin (TSH). This constellation is referred to as nonthyroidal illness syndrome (NTI). Although it is long known that the severity of NTI is associated with risk of poor outcomes of critical illness, the causality in this association has not been well investigated.

SUMMARY

In this narrative review, the different faces of NTI during critical illness are highlighted. Acute alterations are dominated by changes in thyroid hormone binding, peripheral thyroid hormone uptake, and alterations in the expression and activity of the type-1 and type-3 deiodinases. It was recently shown that at least part of these acute changes are brought about by concomitant macronutrient restriction, and this part appears adaptive and beneficial. However, the face of the NTI in the prolonged phase of critical illness is different, when patients are fully fed but continue to depend on intensive medical care. In that prolonged phase of illness, hypothalamic thyrotropin releasing hormone (TRH) expression is suppressed and explains reduced TSH secretion and whereby reduced thyroidal hormone release. During prolonged critical illness, and in the presence of adequate nutrition, several tissue responses could be interpreted as compensatory to low thyroid hormone availability, such as increased expression of monocarboxylate transporters, upregulation of type-2 deiodinase activity, and increased sensitivity at the receptor level. Infusing hypothalamic releasing factors in these prolonged critically ill patients can reactivate the thyroid axis and induce an anabolic response.

CONCLUSIONS

It is clear that the name "NTI" during critical illness refers to a syndrome with different faces. Tolerating the early "fasting response" to critical illness and its concomitant changes in thyroid hormone parameters appears to be wise and beneficial. This thus applies to the NTI present in the majority of the patients treated in intensive care units. However, the NTI that occurs in prolonged critically ill patients appears different with regard to both its causes and consequences. Future studies should specifically target this selected population of prolonged critically ill patients, and, after excluding iatrogic drug interferences, investigate the effect on outcome of treatment with hypothalamic releasing factors in adequately powered randomized controlled trials.

Effect of dopamine infusion on thyroid hormone tests and prolactin levels in very low birth weight infants

OBJECTIVE

To evaluate the effect of dopamine on thyroid hormone tests and prolactin (PRL) and to assess requirement for L-thyroxin (LT4).

METHODS

The infants (n = 102) were divided into three groups (Group 1; received no dopamine, Group 2 received ≤25 mg/kg cumulative dose and Group 3; received >25 mg/kg cumulative dose). Blood samples were taken at 6-8 days (timepoint 1), 13-15 days (timepoint 2), and 4-6 weeks of life (timepoint 3).

RESULTS

Respiratory distress syndrome was higher in group 2 and 3. Patnet ductus arteriosus was higher in group 3 than in groups 1 and 2. Duration and cumulative dose in group 3 were higher than group 2. There was no difference between thyroid hormones that were taken after stopping infusion at timepoint 3 among all groups. No therapy with LT4 was needed. PRL levels were higher at timepoint 1 in group 1 than compared to group 2 and 3 (p < 0.05), and no difference between group 2 and 3 (p > 0.05). This difference was disappeared at following timepoints.

CONCLUSIONS

The release of TSH, FT3, FT4 and PRL were not inhibited and prophylactic thyroid hormone treatment was not required in VLBW infants receiving dopamine infusions.

Endocrine responses to critical illness: novel insights and therapeutic implications

CONTEXT

Critical illness, an extreme form of severe physical stress, is characterized by important endocrine and metabolic changes. Due to critical care medicine, survival from previously lethal conditions has become possible, but many patients now enter a chronic phase of critical illness. The role of the endocrine and metabolic responses to acute and prolonged critical illness in mediating or hampering recovery remains highly debated.

EVIDENCE ACQUISITION

The recent literature on changes within the hypothalamic-pituitary-thyroid axis and the hypothalamic-pituitary-adrenal axis and on hyperglycemia in relation to recovery from critical illness was critically appraised and interpreted against previous insights. Possible therapeutic implications of the novel insights were analyzed. Specific remaining questions were formulated.

EVIDENCE SYNTHESIS

In recent years, important novel insights in the pathophysiology and the consequences of some of these endocrine responses to acute and chronic critical illness were generated. Acute endocrine adaptations are directed toward providing energy and substrates for the vital fight-or-flight response in a context of exogenous substrate deprivation. Distinct endocrine and metabolic alterations characterize the chronic phase of critical illness, which seems to be no longer solely beneficial and could hamper recovery and rehabilitation.

CONCLUSIONS

Important novel insights reshape the current view on endocrine and metabolic responses to critical illness and further clarify underlying pathways. Although many issues remain unresolved, some therapeutic implications were already identified. More work is required to find better treatments, and the optimal timing for such treatments, to further prevent protracted critical illness, to enhance recovery thereof, and to optimize rehabilitation.

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.

Clinical concepts on thyroid emergencies

OBJECTIVE

Thyroid-related emergencies are caused by overt dysfunction of the gland which are so severe that require admission to intensive care units (ICU) frequently. Nonetheless, in the ICU setting, it is crucial to differentiate patients with non-thyroidal illness and alterations in thyroid function tests from those with intrinsic thyroid disease. This review presents and discusses the main etiopathogenetical and clinical aspects of hypothyroid coma (HC) and thyrotoxic storm (TS), including therapeutic strategy flow-charts. Furthermore, a special chapter is dedicated to the approach to massive goiter, which represents a surgical thyroid emergency.

DATA SOURCE

We searched the electronic MEDLINE database on September 2013. Data Selection and Data Extraction: Reviews, original articles, and case reports on "myxedematous coma," "HC," "thyroid storm," "TS," "massive goiter," "huge goiter," "prevalence," "etiology," "diagnosis," "therapy," and "prognosis" were selected.

DATA SYNTHESIS AND CONCLUSION

Severe excess or defect of thyroid hormone is rare conditions, which jeopardize the life of patients in most cases. Both HC and TS are triggered by precipitating factors, which occur in patients with severe hypothyroidism or thyrotoxicosis, respectively. The pillars of HC therapy are high-dose l-thyroxine and/or tri-iodothyroinine; i.v. glucocorticoids; treatment of hydro-electrolyte imbalance (mainly, hyponatraemia); treatment of hypothermia; often, endotracheal intubation and assisted mechanic ventilation are needed. Therapy of TS is based on beta-blockers, thyrostatics, and i.v. glucocorticoids; eventually, high-dose of iodide compounds or lithium carbonate may be of benefit. Surgery represents the gold standard treatment in patients with euthyroid massive nodular goiter, although new techniques - e.g., percutaneous laser ablation - are helpful in subjects at high surgical risk or refusing operation.

Nonthyroidal illness syndrome

PURPOSE OF REVIEW

The current state of the pathophysiology, diagnosis, and therapeutic implications of the nonthyroidal illness syndrome is reviewed.

RECENT FINDINGS

Previous studies attributed the development of the nonthyroidal illness syndrome to alterations in three main areas of thyroid hormone metabolism: deiodinase activity, thyroid-stimulating hormone secretion, and hormone binding to serum proteins. New studies suggest that alterations in thyroid hormone transport into tissues and alterations of the nuclear thyroid hormone receptors may also play a role. Therapy of the nonthyroidal illness syndrome remains a controversial topic.

SUMMARY

Multiple factors lead to the development of the nonthyroidal illness syndrome, including alterations in type 1 and 3 deiodinase activity, thyrotropin-releasing hormone and thyroid-stimulating hormone secretion, hormone binding to plasma proteins, thyroid hormone transporter expression and activity, and the thyroid hormone nuclear receptor complex. These data show that acute and chronic illness affect all aspects of thyroid hormone metabolism and action. Some of these changes are physiologic and some are pharmacologic. The mediators of these alterations are still largely unclear. There continues to be no indication for thyroid hormone therapy in the vast majority of patients with the nonthyroidal illness syndrome, although interesting data suggest a possible role for treating a small subset of patients.

Evaluation of positive inotropic drug effects on thyroid hormone levels after open heart surgery

OBJECTIVE

The aim of this study was to examine the effects of positive inotropic drugs, including adrenaline, dopamine, and dobutamine on thyroid hormone levels following open heart surgery.

METHODS

We analyzed free thyroid hormones (FT3 and FT4) and thyroid-stimulating hormones (TSH) in 200 consecutive patients undergoing open heart surgery. Patients were divided into 5 groups according to the inotropic drug administration as follows: Group A (n = 46) received dopamine alone; Group B (n = 40), dopamine and dobutamine; Group C (n = 36), dopamine, dobutamine, and adrenaline; Group D (n = 32), adrenaline alone; and Group E (n = 46), placebo. Procedural factors affecting thyroid hormones were recorded and included cardiopulmonary bypass (CPB) time, cross-clamping time, degree of hypothermia, and the duration and doses of positive inotropic drugs. Blood samples for hormone assays were collected before initiation of inotropic drug therapy (baseline) and postoperatively at 24, 72, and 120 hours after drug therapy.

RESULTS

FT3, FT4, and TSH levels at baseline were similar in all groups. Although there was a trend showing very slight increases in thyroid hormone levels from baseline to the 24th, 72nd, and 120th postoperative hours after drug therapy, these changes were not significant, and there were also no significant differences between the groups. There was also no significant statistical difference in CPB time, cross-clamping time, degree of hypothermia, and duration and doses of positive inotropic drugs between groups.

CONCLUSION

Although thyroid hormone levels were affected by positive inotropic drug usage after open heart surgery, this effect was not significant and thyroid hormone levels remained within normal ranges.

Endocrine and metabolic changes during sepsis: an update

The authors have reviewed the most recent and relevant literature from which reasonable conclusions may be drawn. This article highlights important endocrine and metabolic changes, and provides possible explanations for observed perturbations. Obviously infectious disease specialists are not charged with the primary responsibility of addressing these issues, which have largely remained the domain of endocrinologists and intensivists. However, infectious disease specialists use a variety of drugs that can contribute to these abnormalities. Therefore, a constant dialogue between specialists would enhance the quality of care and also contribute immensely to favorable outcomes.

Hyperthyroidism

Hyperthyroidism is a pathological syndrome in which tissue is exposed to excessive amounts of circulating thyroid hormone. The most common cause of this syndrome is Graves' disease, followed by toxic multinodular goitre, and solitary hyperfunctioning nodules. Autoimmune postpartum and subacute thyroiditis, tumors that secrete thyrotropin, and drug-induced thyroid dysfunction, are also important causes.<br /> <br />

Low triiodothyronine syndrome: a prognostic marker for outcome in sepsis?

There is ongoing controversy as to whether hormonal changes of the euthyroid sick syndrome are predictors of poor outcome in sepsis and critical illness. In this prospective study, the prognostic accuracy of thyroid hormone levels in 103 critically ill adult patients on admission and during follow up in a medical intensive care unit (ICU) was assessed and was compared to clinical risk scores, namely, the acute physiology and chronic health evaluation and the simplified acute physiology score. Median T3 levels on admission to the ICU were lower in the 53 septic cases [0.9 nmol/l (IQR 0.6-1.1)] as compared with the 50 patients with a systemic inflammatory response syndrome [1.2 nmol/l (IQR 0.8-1.4), P < 0.001]. The lowest T3 levels were found in patients with severe sepsis [0.8 nmol/l (IQR 0.55-0.95)] and septic shock [0.8 nmol/l (IQR 0.6-1.0)]. There was no difference in T3 and free thyroxin (fT4) levels on admission in non-survivors compared with survivors overall and in subgroups of patients with SIRS and sepsis. During the follow up, fT4 levels decreased significantly in non-survivors, while they increased in survivors [fT4 difference -1.3 (IQR -2.5 to 0.2) vs. 0.8 (IQR -0.85 to 4.1), P = 0.003]. In addition, on the day of death, non-survivors had lower T3 and fT4 levels as compared with survivors (P = 0.04 and P = 0.02). T3 and fT4 levels on admission were not prognostic in this cohort of critically ill patients. A decrease in fT4 levels in the course of disease, however, may point to adverse outcome.

Norepinephrine or Dopamine for Septic Shock

Received July 30, 2010, and in revised form September 14, 2010. Accepted for publication September 20, 2010. Background: There is debate as to the vasopressor agent of choice in patients with septic shock. According to current guidelines either dopamine or norepinephrine may be considered as the first-line agent for the management of refractory hypotension of septic shock. Objective: The aim of this systematic review was to evaluate randomized clinical trials which compared norepinephrine versus dopamine in critically ill patients with septic shock or in a population of critically ill patients with shock predominantly secondary to sepsis. Data Sources: MEDLINE, Embase, Scopus, Cochrane Register of Controlled Trials and citation review of relevant primary and review articles. Study Selection: Randomized clinical trials that compared norepinephrine with dopamine in critically ill adults with sepsis and reported the 28-day or in-hospital mortality. Data Extraction: We abstracted data on study design, study setting, patient population, 28-day mortality or in-hospital mortality, rate of arrhythmias, hospital length of stay, and ICU length of stay. Data Synthesis: Six studies met our inclusion criteria. These studies included a total of 2043 participants, with 995 in the norepinephrine and 1048 in the dopamine groups. There were 479 (48%) deaths in the norepinephrine group and 555 (53%) deaths in the dopamine group. There was statistically significant superiority of norepinephrine over dopamine for the outcome of in-hospital or 28-day mortality: pooled RR: 0.91 (95% CI 0.83 to 0.99; P = .028). We also found a statistically significant decrease in the rate of cardiac arrhythmias in the norepinephine group as compared to the dopamine group: pooled RR: 0.43 (95% CI 0.26 to 0.69; P ≤ .001). A subgroup analysis that pooled studies in which all the randomized patients had septic shock demonstrated that norepinephrine improved in-hospital or 28-day mortality; however, the results were no longer statistically significant. Conclusions: The analysis of the pooled studies that included a critically ill population with shock predominantly secondary to sepsis showed superiority of norepinephrine over dopamine for in-hospital or 28-day mortality.

Drug-induced endocrine disorders in the intensive care unit

The neuroendocrine response to critical illness is key to the maintenance of homeostasis. Many of the drugs administered routinely in the intensive care unit significantly impact the neuroendocrine system. These agents can disrupt the hypothalamic-pituitary-adrenal axis, cause thyroid abnormalities, and result in dysglycemia. Herein, we review major drug-induced endocrine disorders and highlight some of the controversies that remain in this area. We also discuss some of the more rare drug-induced syndromes that have been described in the intensive care unit. Drugs that may result in an intensive care unit admission secondary to an endocrine-related adverse event are also included. Unfortunately, very few studies have systematically addressed drug-induced endocrine disorders in the critically ill. Timely identification and appropriate management of drug-induced endocrine adverse events may potentially improve outcomes in the critically ill. However, more research is needed to fully understand the impact of medications on endocrine function in the intensive care unit.

Imbalance between thyroid hormones and the dopaminergic system might be central to the pathophysiology of restless legs syndrome: a hypothesis

Data collected from medical literature indicate that dopaminergic agonists alleviate Restless Legs Syndrome symptoms while dopaminergic agonists antagonists aggravate them. Dopaminergic agonists is a physiological regulator of thyroid-stimulating hormone. Dopaminergic agonists infusion diminishes the levels of thyroid hormones, which have the ability to provoke restlessness, hyperkinetic states, tremors, and insomnia. Conditions associated with higher levels of thyroid hormones, such as pregnancy or hyperthyroidism, have a higher prevalence of Restless Legs Syndrome symptoms. Low iron levels can cause secondary Restless Legs Syndrome or aggravate symptoms of primary disease as well as diminish enzymatic activities that are involved in dopaminergic agonists production and the degradation of thyroid hormones. Moreover, as a result of low iron levels, dopaminergic agonists diminishes and thyroid hormones increase. Iron therapy improves Restless Legs Syndrome symptoms in iron deprived patients. Medical hypothesis. To discuss the theory that thyroid hormones, when not counterbalanced by dopaminergic agonists, may precipitate the signs and symptoms underpinning Restless Legs Syndrome. The main cause of Restless Legs Syndrome might be an imbalance between the dopaminergic agonists system and thyroid hormones.

The syndrome of inherited partial SBP2 deficiency in humans

Selenium (Se) is an essential trace element required for the biosynthesis of selenoproteins. Selenocysteine insertion sequence (SECIS) binding protein 2 (SBP2) represents a key trans-acting factor for the co-translational insertion of selenocysteine into selenoproteins. In 2005, we reported the first mutations in the SBP2 gene in two families in which the probands presented with transient growth retardation associated with abnormal thyroid function tests. Intracellular metabolism of thyroid hormone (TH) and availability of the active hormone, triiodothyronine, is regulated by three selenoprotein iodothyronine deiodinases (Ds). While acquired changes in D activities are common, inherited defects in humans were not known. Affected children were either homozygous or compound heterozygous for SBP2 mutations. Other selenoproteins, glutathione peroxidase, and selenoprotein P were also reduced in affected subjects. Since our initial report, another family manifesting a similar phenotype was found to harbor a novel SBP2 mutation. In vivo studies of these subjects have explored the effects of Se and TH supplementation. In vitro experiments have provided new insights into the effect of SBP2 mutations. In this review we discuss the clinical presentation of SBP2 mutations, their effect on protein function, consequence for selenoproteins, and the clinical course of subjects with SBP2 defects.

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.

Drugs that suppress TSH or cause central hypothyroidism

Many different drugs affect thyroid function. Most of these drugs act at the level of the thyroid in patients with normal thyroid function, or at the level of thyroid hormone absorption or metabolism in patients requiring exogenous levothyroxine. A small subset of medications including glucocorticoids, dopamine agonists, somatostatin analogues and rexinoids affect thyroid function through suppression of TSH in the thyrotrope or hypothalamus. Fortunately, most of these medications do not cause clinically evident central hypothyroidism. A newer class of nuclear hormone receptors agonists, called rexinoids, cause clinically significant central hypothyroidism in most patients and dopamine agonists may exacerbate 'hypothyroidism' in patients with non-thyroidal illness. In this review, we explore mechanisms governing TSH suppression of these drugs and the clinical relevance of these effects.

Sympathetic overstimulation during critical illness: adverse effects of adrenergic stress

The term ''adrenergic'' originates from ''adrenaline'' and describes hormones or drugs whose effects are similar to those of epinephrine. Adrenergic stress is mediated by stimulation of adrenergic receptors and activation of post-receptor pathways. Critical illness is a potent stimulus of the sympathetic nervous system. It is undisputable that the adrenergic-driven ''fight-flight response'' is a physiologically meaningful reaction allowing humans to survive during evolution. However, in critical illness an overshooting stimulation of the sympathetic nervous system may well exceed in time and scope its beneficial effects. Comparable to the overwhelming immune response during sepsis, adrenergic stress in critical illness may get out of control and cause adverse effects. Several organ systems may be affected. The heart seems to be most susceptible to sympathetic overstimulation. Detrimental effects include impaired diastolic function, tachycardia and tachyarrhythmia, myocardial ischemia, stunning, apoptosis and necrosis. Adverse catecholamine effects have been observed in other organs such as the lungs (pulmonary edema, elevated pulmonary arterial pressures), the coagulation (hypercoagulability, thrombus formation), gastrointestinal (hypoperfusion, inhibition of peristalsis), endocrinologic (decreased prolactin, thyroid and growth hormone secretion) and immune systems (immunomodulation, stimulation of bacterial growth), and metabolism (increase in cell energy expenditure, hyperglycemia, catabolism, lipolysis, hyperlactatemia, electrolyte changes), bone marrow (anemia), and skeletal muscles (apoptosis). Potential therapeutic options to reduce excessive adrenergic stress comprise temperature and heart rate control, adequate use of sedative/analgesic drugs, and aiming for reasonable cardiovascular targets, adequate fluid therapy, use of levosimendan, hydrocortisone or supplementary arginine vasopressin.

Hypothalamic-pituitary-thyroid axis changes in children after cardiac surgery

INTRODUCTION

Hypothalamic-pituitary-thyroid axis changes in critical illness result in nonthyroidal illness syndrome (NTIS) characterized by abnormal TSH and thyroid hormone levels. It is unclear whether NTIS is adaptive or maladaptive. Some have suggested that NTIS adversely affects outcome, but there are limited data in children.

OBJECTIVE

Our objective was to determine the natural history of NTIS in children undergoing cardiac bypass surgery and to correlate these changes with outcome and illness severity.

METHODS

Thyroid function was measured in 21 patients, aged 1-11 yr, preoperatively and postoperatively twice daily on postoperative days (POD) 0-3 and daily thereafter until POD 7. Pediatric Logistic Organ Dysfunction and inotrope scores and pediatric intensive care unit, hospital, and ventilation days were measured and statistically analyzed in relation to thyroid function.

RESULTS

All patients exhibited NTIS within the first day postoperatively. TSH recovered by POD 4. Total T(3), free T(3) index, and T(3) uptake were still below preoperative levels on POD 7. NTIS changes correlated to prolonged hospital stays with increased pediatric intensive care unit and mechanical ventilation days and also showed strong relations with Pediatric Logistic Organ Dysfunction and inotrope scores. The T(3) measures drawn within 6-14 h from surgery were predictive of clinical outcome. Alterations in illness severity preceded changes in thyroid function.

CONCLUSION

NTIS was present in this population of critically ill children with some of the biochemical changes not corrected by 8 d postoperatively. The degree of NTIS was related to and predictive of clinical outcome and illness severity.

Low triiodothyronine serum levels as a predictor of poor prognosis in burn patients

OBJECTIVE

Euthyroid sick syndrome is a common finding in critically ill patients with nonthyroidal illness, characterized by low serum levels of free triiodothyronine (fT3) with a peculiar increase in reverse T3 (rT3) and normal-to-low free thyroxine (fT4) as well as thyroid-stimulating hormone (TSH) levels. This condition has been proposed as a prognostic factor of worse outcome in critically ill patients, while no conclusive data are available in burns.

METHODS

Since thyroid function testing is contained in our baseline laboratory tests at admission, we retrospectively evaluated fT3, fT4 and TSH in 295 consecutive burn patients admitted to the Burn Center of Turin from January 2002 to December 2006, comparing hormone levels in survivors and non-survivors.

RESULTS

fT3 and TSH levels were significantly lower (p<or=0.0002) in non-survivors compared to survivors, while no significant difference between the two populations was found in fT4 concentrations. Excluding from the study 20 patients who received dopamine administration for more than 21h, serum fT3 levels fell further still (p=0.0003). In addition, fT3 concentrations showed a significant correlation with burn severity expressed by the Roi score (Spearman's correlation coefficient -0.37 with p<0.00001).

CONCLUSION

Low fT3 levels are associated with poor outcome in burn patients. Hence, fT3 measurement could be proposed as a strong and cost-effective tool of poor prognosis.

Endocrine assessments during critical illness

The evaluation of hormonal status in critically ill patients is challenging and has many pitfalls. This article reviews proper assessment of glycemic status AND adrenal and thyroid function during critical care.

Infection, immunity, and hormones/endocrine interactions

Infections and stress, immune responses, and hormones are interconnected, ensuring immune competence to deal with immediate threat of overwhelming infection and metabolic collapse. Emergence of cytokines as key signal mediators and appreciation of autocrine-paracrine influences of hormones have helped explain how signals are transmitted and responses evoked. This has led to possibilities of creating therapies that might be used to enhance protective signals and dampen signals emanating from host and invading organism interaction that might otherwise be detrimental. Correcting certain metabolic abnormalities, such as hyperglycemia and metabolic acidosis, benefits the host by decreasing morbidity and mortality.

Low-dose dopamine in the intensive care unit

For much of the last four decades, low-dose dopamine has been considered the drug of choice to treat and prevent renal failure in the intensive care unit (ICU). The multifactorial etiology of renal failure in the ICU and the presence of coexisting multisystem organ dysfunction make the design and execution of clinical trials to study this problem difficult. However, in the last decade, several meta-analyses and one large randomized trial have all shown a lack of benefit of low-dose dopamine in improving renal function. There are multiple reasons for this lack of efficacy. While dopamine does cause a diuretic effect, it does very little to improve mortality, creatinine clearance, or the incidence of dialysis. Evidence is also growing of its adverse effects on the immune, endocrine, and respiratory systems. It may also potentially increase mortality in sepsis. It is the opinion of the authors that the practice of using low-dose dopamine should be abandoned. Other drugs and treatment modalities need to be explored to address the serious issue of renal failure in the ICU.

Oral triiodothyronine for the prevention of thyroid hormone reduction in adult valvular cardiac surgery

Treatment of non-thyroidal illness by intravenous triiodothyronine (T3) after cardiac surgery causes a disproportional elevation of hormone levels. The administration of oral T3, which has never been studied in this context, could cause physiological hormone levels. The aim of this study was to test oral T3 for the prevention of T3 reduction during the postoperative period of valvular cardiac surgery in adults. Eighteen patients who underwent cardiac surgery for valvular disease with invasive hemodynamic monitoring were randomly assigned to 2 groups: the T group received oral T3 (N = 8), 25 microg three times/day, initiated 24 h before surgery and maintained for 48 h and the NT group (N = 10) received placebo. Serum T3, thyroxine and thyrotropin were determined at baseline, 1 h before surgery, within 30 min of cardiopulmonary bypass and 6, 12, 24, and 48 h after removal of the aortic cross-clamp. Baseline T3 was similar in both groups (T: 119 +/- 13; NT: 131 +/- 9 ng/dL). Serum T3 increased during the first 24 h in the T group compared to the NT group (232 +/- 18 vs 151 +/- 13 ng/dL; P < 0.001). In the NT group, T3 was reduced by 24% (P = 0.007) 6 h after removal of the aortic cross-clamp, confirming the non-thyroidal illness syndrome. There were no differences in clinical or hemodynamic parameters between groups. Administration of oral T3 prevented its serum reduction after valvular cardiac surgery in adults, with normal serum levels for 48 h without disproportional elevations.

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.

Catecholamines and vasopressin during critical illness

This article summarizes the effects of catecholamines and vasopressin on the cardiovascular system, focusing on their metabolic and immunologic properties. Particular attention is dedicated to the septic shock condition.

Changes within the thyroid axis during the course of critical illness

This article reviews the mechanisms behind the observed changes in plasma thyroid hormone levels in the acute phase and the prolonged phase of critical illness. It focuses on the neuroendocrinology of the low triiodothyronine syndrome and on thyroid hormone metabolism by deiodination and transport.

Prevalence of subclinical thyroid dysfunction and its relation to socioeconomic deprivation in the elderly: a community-based cross-sectional survey

CONTEXT

Population-based screening has been advocated for subclinical thyroid dysfunction in the elderly because the disorder is perceived to be common, and health benefits may be accrued by detection and treatment.

OBJECTIVE

The objective of the study was to determine the prevalence of subclinical thyroid dysfunction and unidentified overt thyroid dysfunction in an elderly population.

DESIGN, SETTING, AND PARTICIPANTS

A cross-sectional survey of a community sample of participants aged 65 yr and older registered with 20 family practices in the United Kingdom.

EXCLUSIONS

Exclusions included current therapy for thyroid disease, thyroid surgery, or treatment within 12 months.

OUTCOME MEASURE

Tests of thyroid function (TSH concentration and free T4 concentration in all, with measurement of free T3 in those with low TSH) were conducted. EXPLANATORY VARIABLES: These included all current medical diagnoses and drug therapies, age, gender, and socioeconomic deprivation (Index of Multiple Deprivation, 2004).

ANALYSIS

Standardized prevalence rates were analyzed. Logistic regression modeling was used to determine factors associated with the presence of subclinical thyroid dysfunction.

RESULTS

A total of 5960 attended for screening. Using biochemical definitions, 94.2% [95% confidence interval (CI) 93.8-94.6%] were euthyroid. Unidentified overt hyper- and hypothyroidism were uncommon (0.3, 0.4%, respectively). Subclinical hyperthyroidism and hypothyroidism were identified with similar frequency (2.1%, 95% CI 1.8-2.3%; 2.9%, 95% CI 2.6-3.1%, respectively). Subclinical thyroid dysfunction was more common in females (P < 0.001) and with increasing age (P < 0.001). After allowing for comorbidities, concurrent drug therapies, age, and gender, an association between subclinical hyperthyroidism and a composite measure of socioeconomic deprivation remained.

CONCLUSIONS

Undiagnosed overt thyroid dysfunction is uncommon. The prevalence of subclinical thyroid dysfunction is 5%. We have, for the first time, identified an independent association between the prevalence of subclinical thyroid dysfunction and deprivation that cannot be explained solely by the greater burden of chronic disease and/or consequent drug therapies in the deprived population.

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.

Non-thyroidal illness syndrome is a manifestation of hypothalamic-pituitary dysfunction, and in view of current evidence, should be treated with appropriate replacement therapies

This article documents the role of hypothalamic hypothyroidism and decreased T4-->T3 conversion as the cause of low T4 and T3 in non-thyroidal illness syndrome (NTIS). This article also presents the arguments for administration of replacement triiodothyronine (T3) and thyroxine (T4) hormone in patients who have NTIS. It is impossible to be certain at this time that it is beneficial to replace hormone, or whether this could be harmful. Only a prospective study will be adequate to prove this point, and probably this would need to involve hundreds of patients. If effective, thyroid hormone replacement will be one of many beneficial treatments given the patient, rather than a single magic bullet, which would reverse all the metabolic changes going wrong in these severely ill patients.

Catecholamines and vasopressin during critical illness

In critical care medicine, catecholamines are most widely used to reverse circulatory dysfunction and thus to restore tissue perfusion. However, catecholamines not only influence systemic and regional hemodynamics, but also exert a variety of significant metabolic, endocrine, and immunologic effects. Arginine vasopressin is a vasomodulatory hormone with potency to restore vascular tone in vasodilatory hypotension. Although the evidence supporting the use of low doses of vasopressin or its analogs in vasodilatory shock is increasing, lack of data regarding mortality and morbidity prevent their implementation in critical care protocols.