Steroid hormone analysis of adolescents and young women with polycystic ovarian syndrome and adrenocortical dysfunction using UPC2-MS/MS.

BACKGROUND: We recently identified 35 women with polycystic ovarian syndrome (PCOS) who exhibited features of micronodular adrenocortical hyperplasia. Steroid hormone analysis can be more accurate using state-of-the-art ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS/MS). We hypothesized that UPC2-MS/MS may be used to better define hormonally this distinct subgroup of patients with PCOS. METHODS: Plasma from PCOS patients (n = 35) and healthy volunteers (HVs, n = 19) who all received dexamethasone testing was analyzed. Samples were grouped per dexamethasone responses and followed by UPC2-MS/MS analysis. When insufficient, samples were pooled from patients with similar responses to allow quantification over the low end of the assay. RESULTS: The C11-oxy C19 (11ß-hydroxyandrostenedione, 11keto-androstenedione, 11ß-hydroxytestosterone, 11keto-testosterone):C19 (androstenedione, testosterone) steroid ratio was decreased by 1.75-fold in PCOS patients compared to HVs. Downstream steroid metabolites 11ß-hydroxyandrosterone and 11keto-androsterone were also measurable. The C11-oxy C21 steroids, 11-hydroxyprogesterone and 11keto-dihydroprogesterone levels, were 1.2- and 1.7-fold higher in PCOS patients compared to HVs, respectively. CONCLUSIONS: We hypothesized that UPC2-MS/MS may accurately quantify steroids, in vivo, and identify novel metabolites in a subgroup of patients with PCOS and adrenal abnormalities. Indeed, it appears that adrenal C11-oxy steroids have the potential of being used diagnostically to identify younger women and adolescents with PCOS who also have some evidence of micronodular adrenocortical hyperplasia. IMPACT: Adrenal C11-oxy steroids may be clinically important in identifying young patients with PCOS and adrenal abnormalities. The steroids presented in our manuscript have not yet been considered in the clinical setting so far, and we believe that this study could represent a first focused step towards the characterization of a distinct subgroup of women with PCOS who may in fact be treated differently than the average patient with PCOS. This paper can change the understanding of PCOS as one disorder: it is in fact a heterogeneous condition. In addition, for the subgroup of patients with PCOS associated with adrenocortical dysfunction, our paper provides novel hormonal markers that can be used diagnostically. Finally, the paper also adds to the basic pathophysiological understanding of adrenocortical-ovarian interactions in steroidogenesis of young women and adolescent girls with PCOS.

Laparoscopic cortical-sparing adrenal surgery in pheochromocytomas associated with hereditary neoplasia syndromes.

INTRODUCTION: Pheochromocytomas in hereditary syndromes tend to grow multifocal with adrenal involvement on both sides. Surgical treatment with bilateral adrenalectomy inevitably leads to life-long hormonal dependence, which significantly affects quality of life. The development of minimally invasive adrenal surgery has created a chance to preserve adrenal cortex function in these patients. The aim of the present study was to evaluate the safety of laparoscopic cortical-sparing adrenal surgeries and their efficacy in the prevention of postoperative adrenal insufficiency in patients with hereditary pheochromocytomas. MATERIAL AND METHODS: We retrospectively analysed the medical histories of 10 patients, who underwent 10 laparoscopic cortical sparing adrenal surgeries from January 2015 to January 2019 in our centre. The decision to perform sparing surgery was based on preoperative diagnosis of hereditary syndrome in line with the result of DNA analysis or its diagnosis based on the clinical appearance. All surgeries were performed laparoscopically from transperitoneal access in the lateral decubitus position, with preserving 1/3-1/4 adrenal tissue. The sufficiency of remnant adrenal tissue was assessed in all patients. The median time of follow-up was three years (ranged 0.5-4 years). RESULTS: No intraoperative complications were observed. One case of acute heart failure was the only early postoperative adverse event. There were no late postoperative complications and no local recurrences observed. In one out of three patients undergoing sparing surgery as a second procedure after former total adrenalectomy, adrenal cortex failure occurred. In all patients after unilateral surgery or after bilateral surgery performed simultaneously (total adrenalectomy at one side and sparing surgery contralaterally), function of remnant adrenal tissue was preserved. CONCLUSIONS: In hereditary pheochromocytomas, with minimal risk of malignant process, laparoscopic cortical sparing adrenal surgeries are the safe approach and provide the chance to preserve adrenal cortex function.

Adrenocortical tumors in children.

Adrenocortical neoplasms are rare in childhood. Unlike their adult counterparts, they are often hormonally active and malignant. Despite being uncommon, adrenocortical neoplasms in children have significant associated morbidity and require complete surgical resection for effective management. Furthermore, the clinical overlap between adrenocortical neoplasms, adrenal medullary neoplasms, and functional disorders of the adrenal cortex requires that the practicing pediatric surgeon have a solid working knowledge of the presentation, diagnostic workup, and management of these anatomically related yet disparate pathologies.

Steroid Profiling and Immunohistochemistry for Subtyping and Outcome Prediction in Primary Aldosteronism-a Review.

PURPOSE OF REVIEW: Steroid profiling and immunohistochemistry are both promising new tools used to improve diagnostic accuracy in the work-up of primary aldosteronism (PA) and to predict treatment outcomes. Herein, we review the recent literature and present an outlook to the future of diagnostics and therapeutic decision-making in patients with PA. RECENT FINDING: PA is the most common endocrine cause of arterial hypertension and unilateral forms of the disease are potentially curable by surgical resection of the overactive adrenal. Recent studies have shown that adrenal steroid profiling by liquid chromatography-tandem mass spectrometry (LC-MS/MS) can be helpful for subtyping unilateral and bilateral forms of PA, classifying patients with a unilateral aldosterone-producing adenoma (APA) according to the presence of driver mutations of aldosterone production in APAs, and potentially predicting the outcomes of surgical treatment for unilateral PA. Following adrenalectomy, immunohistochemistry of aldosterone synthase (CYP11B2) in resected adrenals is a new tool to analyze "functional" histopathology and may be an indicator of biochemical outcomes after surgery. Biochemical and clinical outcomes of therapy in PA vary widely among patients. Peripheral venous steroid profiling at baseline could improve diagnostic accuracy and help in surgical decision-making in cases of a suspected APA; results of "functional" histopathology could help determine which patients are likely to need close post-surgical follow-up for persistent aldosteronism.

Determination of salivary cortisol to assess time-related changes of the adrenal response to stress in critically ill patients.

BACKGROUND: The value of salivary cortisol measurement to study stress-related adrenal response is controversial. The study aim was to assess the role of salivary cortisol measurement to detect time-related changes of adrenal response in critically ill patients. PATIENTS AND METHODS: Patients with organ failure, sepsis or trauma were prospectively recruited in the Emergency Department. Serum and salivary cortisol were measured at baseline (T0) and after 48 h (T48). In 33 patients ACTH test was also done. RESULTS: Fifty-five patients were studied and classified as septic (22) or non-septic (33). We found a significant correlation between serum and salivary cortisol at T0 and T48. No patient had baseline serum cortisol < 276 nmol/L and salivary cortisol significantly decreased at T48 in almost all patients. A delta serum cortisol < 250 nmol/L after ACTH was found in only 4 patients who showed elevated baseline cortisol levels. CONCLUSION: We found that reduced baseline and post-ACTH cortisol levels are uncommon in our samples. In patients able to provide adequate saliva samples, salivary cortisol may be used to check the degree of stress-induced response and appears as a suitable tool for multiple measurements over time.

The adrenal cortex: Physiology and diseases in human pregnancy.

Pregnancy is characterized by marked alterations in the hypothalamic-pituitary-adrenal axis and in the function of the adrenal gland. Some of those alterations have clinical characteristics that are similar to those of adrenal gland disorders. While adrenal disorders are rare among pregnant women, they harbor the potential for significant morbidity if they remain unrecognized and untreated. As the majority of patients with adrenal disorders present with clinical features that are typical of normal pregnancy - diagnosis during pregnancy is not uncommonly delayed. A high index of suspicion must be practiced for these disorders as they might carry severe obstetrical negative outcomes. In this review we will survey the normal function of adrenal glands in pregnancy and the role of adrenal hormones in pregnancy. We will outline the adrenal disorders that commonly present during pregnancy and review the literature on treatment modalities.

Child Maltreatment and Mother-Child Transmission of Stress Physiology.

In the current study, we examined the attunement and transmission of mother-child diurnal cortisol among maltreating (N = 165) and nonmaltreating (N = 83) mothers and their preschool-aged children. Over half of the families had a substantiated child maltreatment case with the mother as the perpetrator. Mothers collected three saliva samples (waking, midday, and bedtime) on themselves and their child on two consecutive days, which were later assayed for cortisol. This design allows for the examination of concurrent attunement, as well as cross-lagged transmission, across the day. Results from actor-partner interdependence models revealed significant differences in mother-child cortisol attunement and transmission between the maltreating and nonmaltreating groups. Specifically, only maltreating mothers transmitted cortisol to their children and were attuned at first waking; only nonmaltreating dyads were attuned at midday. Implications of these results for sociocultural models of stress physiology and for our understanding of how child maltreatment affects diurnal cortisol regulation are discussed.

Chronic and acute stress monitoring by electrophysiological signals from adrenal gland.

We present electrophysiological (EP) signals correlated with cellular cell activities in the adrenal cortex and medulla using an adrenal gland implantable flexible EP probe. With such a probe, we could observe the EP signals from the adrenal cortex and medulla in response to various stress stimuli, such as enhanced hormone activity with adrenocorticotropic hormone, a biomarker for chronic stress response, and an actual stress environment, like a forced swimming test. This technique could be useful to continuously monitor the elevation of cortisol level, a useful indicator of chronic stress that potentially causes various diseases.

Intermittent hypoxia improves behavioral and adrenal gland dysfunction induced by posttraumatic stress disorder in rats.

Nonpharmacological treatments of stress-induced disorders are promising, since they enhance endogenous stress defense systems, are free of side effects, and have few contraindications. The present study tested the hypothesis that intermittent hypoxia conditioning (IHC) ameliorates behavioral, biochemical, and morphological signs of experimental posttraumatic stress disorder (PTSD) induced in rats with a model of predator stress (10-day exposure to cat urine scent, 15 min daily followed by 14 days of stress-free rest). After the last day of stress exposure, rats were conditioned in an altitude chamber for 14 days at a 1,000-m simulated altitude for 30 min on day 1 with altitude and duration progressively increasing to 4,000 m for 4 h on day 5. PTSD was associated with decreased time spent in open arms and increased time spent in closed arms of the elevated X-maze, increased anxiety index, and increased rate of freezing responses. Functional and structural signs of adrenal cortex degeneration were also observed, including decreased plasma concentration of corticosterone, decreased weight of adrenal glands, reduced thickness of the fasciculate zone, and hydropic degeneration of adrenal gland cells. The thickness of the adrenal fasciculate zone negatively correlated with the anxiety index. IHC alleviated both behavioral signs of PTSD and morphological evidence of adrenal cortex dystrophy. Also, IHC alone exerted an antistress effect, which was evident from the increased time spent in open arms of the elevated X-maze and a lower number of rats displaying freezing responses. Therefore, IHC of rats with experimental PTSD reduced behavioral signs of the condition and damage to the adrenal glands. NEW & NOTEWORTHY Intermittent hypoxia conditioning (IHC) has been shown to be cardio-, vaso-, and neuroprotective. For the first time, in a model of posttraumatic stress disorder (PTSD), this study showed that IHC alleviated both PTSD-induced behavioral disorders and functional and morphological damage to the adrenal glands. Also, IHC alone exerted an antistress effect. These results suggest that IHC may be a promising complementary treatment for PTSD-associated disorders.

Insufficiency of the zona glomerulosa of the adrenal cortex and progressive kidney insufficiency following unilateral adrenalectomy - case report and discussion.

BACKGROUND: Primary aldosteronism (PA) is the most common cause of secondary hypertension and bilateral adrenal hyperplasia (BAH) and aldosterone-producing adenoma (APA) seem to be the most common causes of PA. Unilateral adrenalectomy (UA) is the preferred treatment for APA, although the benefits are still difficult to assess. CASE REPORT: We present a case report of a 69-year old man with a 30 year history of hypertension and probably long-standing PA due to APA, with typical organ complications. Since repeated abdominal CT scans were equivocal, not showing radiological changes characteristic for PA, the diagnosis of APA was delayed and was only finally confirmed by adrenal venous sampling which demonstrated unilateral aldosteronism. The patient underwent UA, complicated by mineralocorticoid deficiency syndrome and increased creatinine and potassium levels. At 12 months follow-up the patient still had hyperkalemia and was fludrocortisone dependent. CONCLUSIONS: Older patients and patients with long-lasting PA who are treated with UA may demonstrate deterioration of renal function and develop transient or persistent insufficiency of the zona glomerulosa of the remaining adrenal gland necessitating fludrocortisone supplementation. Transient hyperkalemia may be observed following UA as a result of the prolonged effects of aldosterone antagonists and/or transient mineralocorticoid/glucocorticoid insufficiency. Additionally, the level of progression of chronic kidney disease after UA is difficult to predict. There likely exists a group of patients who might paradoxically have higher cardiovascular risk due to significant deterioration in kidney function not only resulting from the removal of the aldosterone induced glomerular hyperfiltration phenomenon. Identification of such a group requires further detailed investigation.

Copeptin as a marker of an altered CRH axis in pituitary disease.

BACKGROUND: Copeptin (pre-proAVP) secreted in equimolar amounts with vasopressin closely reflects vasopressin release. Copeptin has been shown to subtly mirror stress potentially mediated via corticotrophin-releasing hormone. To further test a potential direct interaction of corticotrophin-releasing hormone with copeptin release, which could augment vasopressin effects on pituitary function, we investigated copeptin response to corticotrophin-releasing hormone. PATIENTS AND METHODS: Cortisol, adrenocorticotropin and copeptin were measured in 18 healthy controls and 29 subjects with a history of pituitary disease during standard corticotrophin-releasing hormone test. RESULTS: Patients with previous pituitary disease were subdivided in a group passing the test (P1, n = 20) and failing (P2, n = 9). The overall copeptin response was higher in controls than in subjects with pituitary disease (area under the curve, p = 0.04 for P1 + P2) with a maximum increase in controls from 3.84 ± 2.86 to 12.65 ± 24.87 pmol/L at 30 min, p < 0.05. In contrast, both groups of pituitary patients lacked a significant copeptin response to corticotrophin-releasing hormone, and even in P1, where adrenocorticotropin concentrations increased fourfold (mean, 21.48 vs. 91.53 pg/mL, p < 0.01), copeptin did not respond (e.g., 4.35 ± 5.81 vs. 5.36 ± 6.79 pmol/L, at 30 min, p = ns). CONCLUSIONS: Corticotrophin-releasing hormone is able to stimulate copeptin release in healthy controls suggesting a direct interaction of corticotrophin-releasing hormone and vasopressin/vasopressin. Interestingly, this relation is altered already in the group of pituitary patients who pass the standard corticotrophin-releasing hormone test indicating (1) the corticotrophin-releasing hormone-adrenocorticotropin-cortisol response is largely independent from the vasopressin system, but (2) the corticotrophin-releasing hormone-vasopressin interaction reflected by copeptin may be much more sensitive to reveal subtle alterations in the regulation of pituitary function.

[Adrenal crisis]. / Nebennierenkrise.

Patients with chronic adrenal insufficiency suffer from reduced quality of life and increased mortality. An association between mortality and adrenal crisis is assumed. The frequency of adrenal crisis is about 8/100 patient years. The main causes are infectious disease. Pathophysiology is poorly understood to date. An association with an exaggerated inflammatory response due to a lack of glucocorticoid modulation as well as mineralocorticoid deficiency and diminished adrenomedullary function are discussed. The therapy of adrenal crisis includes prompt parenteral administration of hydrocortisone combined with isotonic saline. To prevent adrenal crisis, patients are equipped with an emergency card and set and educated in glucocorticoid dose adjustment.

Death of adrenocortical cells during murine acute T. cruzi infection is not associated with TNF-R1 signaling but mostly with the type II pathway of Fas-mediated apoptosis.

Earlier studies from our laboratory demonstrated that acute experimental Trypanosoma cruzi infection promotes an intense inflammation along with a sepsis-like dysregulated adrenal response characterized by normal levels of ACTH with raised glucocorticoid secretion. Inflammation was also known to result in adrenal cell apoptosis, which in turn may influence HPA axis uncoupling. To explore factors and pathways which may be involved in the apoptosis of adrenal cells, together with its impact on the functionality of the gland, we carried out a series of studies in mice lacking death receptors, such as TNF-R1 (C57BL/6-Tnfrsf1a tm1Imx or TNF-R1-/-) or Fas ligand (C57BL/6 Fas-deficient lpr mice), undergoing acute T. cruzi infection. Here we demonstrate that the late hypercorticosterolism seen in C57BL/6 mice during acute T. cruzi infection coexists with and hyperplasia and hypertrophy of zona fasciculata, paralleled by increased number of apoptotic cells. Apoptosis seems to be mediated mainly by the type II pathway of Fas-mediated apoptosis, which engages the mitochondrial pathway of apoptosis triggering the cytochrome c release to increase caspase-3 activation. Fas-induced apoptosis of adrenocortical cells is also related with an exacerbated production of intra-adrenal cytokines that probably maintain the late supply of adrenal hormones during host response. Present results shed light on the molecular mechanisms dealing with these phenomena which are crucial not only for the development of interventions attempting to avoid adrenal dysfunction, but also for its wide occurrence in other infectious-based critical illnesses.

Total and free cortisol levels during 1 µg, 25 µg, and 250 µg cosyntropin stimulation tests compared to insulin tolerance test: results of a randomized, prospective, pilot study.

PURPOSE: The appropriate cosyntropin dose during cosyntropin stimulation tests remains uncertain. We conducted a prospective, randomized pilot study to compare 1 µg IV low dose cosyntropin test, 25 µg IM medium dose cosyntropin test, and 250 µg IM standard dose cosyntropin test to evaluate secondary adrenal insufficiency. Insulin tolerance test was used as the gold standard. METHOD: The study included patients with hypothalamic/pituitary disease (n = 10) with at least one pituitary axis deficiency other than ACTH deficiency and controls (n = 12). All tests were done in random order. Sensitivity and specificity were calculated for total cortisol and serum free cortisol cut-off levels during cosyntropin stimulation tests. RESULTS: The median (range) age and F/M sex ratios for patients and controls were 54 years (23-62), 2/8, and 33 years (21-51), 6/6, respectively. The best total cortisol cut-off during low dose cosyntropin test, medium dose cosyntropin test, 30 min and 60 min standard dose cosyntropin test were 14.6 µg/dL (100% sensitivity & specificity), 18.7 µg/dL (100% sensitivity, 88% specificity), 16.1 (100% sensitivity & specificity), and 19.5 µg/dL (100% sensitivity & specificity), respectively. There was no difference in the ROC curve for cortisol values between the cosyntropin stimulation tests (p > 0.41). Using a cortisol cut-off of 18 µg/dL during cosyntropin stimulation tests, only cortisol level at 30 min during standard dose cosyntropin test provided discrimination similar to insulin tolerance test. The best peak free cortisol cut-off levels were 1 µg/dL for insulin tolerance test, 0.9 µg/dL for low dose cosyntropin test, 0.9 µg/dL for medium dose cosyntropin test, and 0.9 µg/dL and 1.3 µg/dL for 30 min and 60 min standard dose cosyntropin test, respectively. CONCLUSION: All cosyntropin stimulation tests had excellent correlations with insulin tolerance test, when appropriate cut-offs were used. This pilot study does not suggest an advantage in using 25 µg cosyntropin dose during the cosyntropin stimulation test. A serum free cortisol cut-off of 0.9 µg/dL may be used as pass criterion during low dose cosyntropin test, standard dose cosyntropin test cosyntropin test, and 30 min standard dose cosyntropin test.

Mother-child adrenocortical synchrony; Moderation by dyadic relational behavior.

Mother-child adrenocortical synchrony, the coupling of cortisol (CT) secretion in mother and child, has been associated with shared parent-child experiences and maladaptive familial contexts. Yet, few studies tested adrenocortical synchrony in diurnal CT patterns. Guided by the bio-behavioral synchrony model, we examined whether mother-child relational behavior and maternal psychopathology may moderate the degree of concordance between mother and child's diurnal CT. Ninety-seven mothers and their six-year old children participated in two groups; mothers diagnosed with major depression disorder (N=28) and non-depressed controls (N=69). Mother-child interactions were observed and coded for dyadic reciprocity and dyadic tension and diurnal cortisol was collected from mother and child over two consecutive weekend days. Concordance between maternal and child's diurnal CT was found, significant above and beyond time of measurement. Maternal depression, while associated with attenuated child diurnal CT variability, was unrelated to adrenocortical synchrony. Higher child diurnal CT production predicted a stronger linkage between maternal and child's diurnal CT, suggesting that greater child physiological stress is associated with increased susceptibility to the influences of maternal stress physiology. Mother-child reciprocity was related to lower adrenocortical synchrony. Findings suggest that higher adrenocortical synchrony is associated with greater physiological stress and less adaptive dyadic relational patterns. Results raise the possibility that diurnal adrenocortical synchrony taps a unique aspect of HPA-axis functioning whose role in the cross-generational transfer of stress physiology requires further research.

Total and free cortisol responses and their relation to outcomes after cardiopulmonary bypass in infants.

BACKGROUND: Hypothalamic-pituitary-adrenal (HPA) axis dysfunction may be partially responsible for the hemodynamic instability experienced by infants after cardiopulmonary bypass (CPB). We report the full spectrum of the HPA response surrounding CPB for infant congenital cardiac surgery. METHODS: We enrolled 84 infants who received 1 mg/kg of dexamethasone before initiation of CPB. Total cortisol (TC), free cortisol (FC), adrenocorticotropic hormone (ACTH), and corticosteroid-binding globulin (CBG) were measured at 3 time points: immediately before CPB (TP1), on intensive care unit arrival (TP2), and at 24 hours after surgery (TP3). A 1-µg ACTH stimulation test was performed at each time point to evaluate adrenal responsiveness. RESULTS: Sixty-eight infants completed all study procedures. Levels of TC, FC, CBG, and ACTH decreased significantly between the preoperative and 24-hour postoperative measurements. There were no significant associations between preoperative FC responses and clinical outcomes after adjusting for weight and Risk-Adjusted Scores for Congenital Heart Surgery. Infants with subnormal TC responses to ACTH stimulation (<9 µg/dL) at TP2 had greater fluid requirements (P < .001) and greater chest tube output (P < .001) during the first 24 hours, as well as longer length of stay (LOS) (P = .007). Except for LOS, these differences persisted for infants with subnormal stimulation tests at TP3. CONCLUSIONS: We observed a significant decline in all aspects of the HPA axis throughout the first 24 hours after infant CPB. TC and FC levels were not associated with clinical outcomes. Subnormal (Δ <9 µg/dL) TC response to cosyntropin stimulation during the postoperative period was associated with increased fluid resuscitation and greater LOS.

MANAGEMENT OF ENDOCRINE DISEASE: Regenerative therapies in autoimmune Addison's disease.

The treatment for autoimmune Addison's disease (AAD) has remained virtually unchanged in the last 60 years. Most patients have symptoms that are relatively well controlled with exogenous steroid replacement, but there may be persistent symptoms, recurrent adrenal crisis and poor quality of life, despite good compliance with optimal current treatments. Treatment with conventional exogenous steroid therapy is also associated with premature mortality, increased cardiovascular risk and complications related to excessive steroid replacement. Hence, novel therapeutic approaches have emerged in the last decade attempting to improve the long-term outcome and quality of life of patients with AAD. This review discusses the recent developments in treatment innovations for AAD, including the novel exogenous steroid formulations with the intention of mimicking the physiological biorhythm of cortisol secretion. Our group has also carried out a few studies attempting to restore endogenous glucocorticoid production via immunomodulatory and regenerative medicine approaches. The recent advances in the understanding of adrenocortical stem cell biology, and adrenal plasticity will also be discussed to help comprehend the science behind the therapeutic approaches adopted.

Major depressive disorder.

Major depressive disorder (MDD) is a debilitating disease that is characterized by depressed mood, diminished interests, impaired cognitive function and vegetative symptoms, such as disturbed sleep or appetite. MDD occurs about twice as often in women than it does in men and affects one in six adults in their lifetime. The aetiology of MDD is multifactorial and its heritability is estimated to be approximately 35%. In addition, environmental factors, such as sexual, physical or emotional abuse during childhood, are strongly associated with the risk of developing MDD. No established mechanism can explain all aspects of the disease. However, MDD is associated with alterations in regional brain volumes, particularly the hippocampus, and with functional changes in brain circuits, such as the cognitive control network and the affective-salience network. Furthermore, disturbances in the main neurobiological stress-responsive systems, including the hypothalamic-pituitary-adrenal axis and the immune system, occur in MDD. Management primarily comprises psychotherapy and pharmacological treatment. For treatment-resistant patients who have not responded to several augmentation or combination treatment attempts, electroconvulsive therapy is the treatment with the best empirical evidence. In this Primer, we provide an overview of the current evidence of MDD, including its epidemiology, aetiology, pathophysiology, diagnosis and treatment.