The Hypothalamic-Pituitary-Thyroid Axis in Cushing Syndrome Before and After Curative Surgery

USP8 Mutations Associated with Cushing's Disease Alter Protein Structure Dynamics

The adenomas in Cushing's disease frequently exhibit mutations in exon 14, within a binding motif for the regulatory protein 14-3-3 located between the catalytic domain (DUB), responsible for ubiquitin hydrolysis, and the WW-like domain that mediates autoinhibition, resulting in constantly active USP8. The exact molecular mechanism of deubiquitinase activity disruption in Cushing's disease remains unclear. To address this, Sanger sequencing of USP8 was performed to identify mutations in corticotropinomas. These mutations were subjected to computational screening, followed by molecular dynamics simulations to assess the structural alterations that might change the biological activity of USP8. Eight different variants of the USP8 gene were identified both within and outside the "hotspot" region. Six of these had previously been reported in Cushing's disease, while two were detected for the first time in our patients with CD. One of the two new variants, initially classified as benign during screening, was found in the neighboring SH3 binding motif at a distance of 20 amino acids. This variant demonstrated pathogenicity patterns similar to those of known pathogenic variants. All USP8 variants identified in our patients caused conformational changes in the USP8 protein in a similar manner. The identified mutations, despite differences in annotation results-including evolutionary conservation assessments, automated predictor data, and variations in localization within exon 14-exhibit similar patterns of protein conformational change. This suggests a pathogenic effect that contributes to the development of CD.

Thyroid function spectrum in Cushing's syndrome

PURPOSE

Thyroid disorders have been reported in hypercortisolism patients. Endogenous Cushing's syndrome (CS) potentially complicates its metabolic sequelae. We investigated thyroid function in CS patients to determine this relationship.

METHODS

In this cross-sectional study, we screened CS patients from 2016 to 2019 at our hospital. Patient demographic, medical history, and laboratory data were collected. Additionally, we performed a meta-analysis to demonstrate the prevalence of thyroid dysfunction in patients with CS.

RESULTS

Among 129 CS patients, 48.6% had triiodothyronine (TT3), 27.9% had thyroxine (TT4), 24.6% had free T3 (FT3), 27.7% had free T4 (FT4), and 6.2% had thyroid-stimulating hormone (TSH) levels below the reference values. Those with clinical CS showed more pronounced thyroid suppression than did those with subclinical CS. Cortisol levels were markedly greater in patients with pituitary hypothyroidism (P < 0.001). Serum cortisol levels throughout the day and post low-dose dexamethasone-suppression test (LDDST) results correlated with thyroid hormone levels, particularly in ACTH-independent CS. Correlations varied by thyroid status; FT3 and TSH were linked to cortisol in euthyroid individuals but not in those with low T3 or central hypothyroidism. TSH levels notably halved from the lowest to highest cortisol tertile post-LDDST. Finally, meta-analysis showed 22.7% (95% CI 12.6%-32.9%) central hypothyroidism in 528 CS patients of nine studies.

CONCLUSION

Thyroid hormone levels are significantly correlated with cortisol levels and are impaired in patients with CS. However, the physiological adaptation and pathological conditions need further study.

Evaluation of non-thyroidal illness syndrome in shock patients admitted to pediatric intensive care unit in a developing country

During critical illness, children my experience various changes in their thyroid hormone levels. Such changes are termed non-thyroidal illness syndrome (NTI). The extent of change correlates with the severity of the illness and its outcomes in critically ill patients. This study aimed to investigate the correlation between the severity of shock and thyroid hormone derangement. This prospective observational study included forty patients aged one month to five years who were admitted to the pediatric intensive care unit (PICU) with shock. Thyroid function tests were conducted on admission, after shock reversal, and five days later. NTI patterns were observed in 70% of patients. The PIM2 score showed a significant negative correlation with T3 (r =  - 0.353, p = 0.026) and FT3 levels on admission (r =  - 0.417, p = 0.007). Furthermore, after shock reversal, the PIM2 score continued to exhibit significant negative correlations with T4 (r =  - 0.444, p = 0.004), T3 (r =  - 0.329, p = 0.038), FT3 (r =  - 0.355, p = 0.025), and FT4 levels (r =  - 0.379, p = 0.016).    Conclusion: This study underscores the high prevalence of NTI in PICU shock patients and suggests monitoring thyroid hormone levels for outcome prediction and treatment guidance. Further research is needed to optimize NTI management in critically ill children. What is Known: • Non-thyroidal illness syndrome (NTIS) is a condition observed in critically ill patients. • There has been limited research on NTI in children, and existing studies have generated conflicting results regarding the relationship between thyroid hormones and clinical outcomes in cases of sepsis and septic shock. What is New: • The study has revealed dynamic changes in free triiodothyronine (FT3) levels during the process of shock reversal and recovery in children who experienced shock. • A significant negative correlation was found between the Pediatric Index of Mortality 2 (PIM2) score and several thyroid hormone levels, including FT3 on admission and T4, FT3, and FT4 on shock reversal.

Effects of sub-chronic exposure to microcystin-LR on the endocrine system of male rats

Microcystins (MCs) can cause reproductive and developmental toxicity and disrupt endocrine homeostasis in mammals. In the present study, male, Sprague-Dawley (SD) rats were administrated 3 or 30 μg MC-LR/kg, body mass (bm) per day via intraperitoneal (i.p.) injections for 6 weeks. Effects of MC-LR on histology, hormone concentrations, gene transcriptional profiles and protein expressions along the hypothalamic-pituitary-adrenal (HPA), -gonad (HPG) and -thyroid (HPT) axes were assessed. Sub-chronic administration with MC-LR caused histological damage to hypothalamus, pituitary, adrenal, testes and thyroid and affected relative masses of pituitary, adrenal and testes. The HPA axis was activated and serum concentrations of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were significantly augmented. Along the HPG axis, serum concentrations of gonadotropin-releasing hormone (GnRH) and dihydrotestosterone (DHT) were diminished, while concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T) and estradiol (E2) were augmented. For the HPT axis, only concentrations of free tetra-iodothyronine (fT4) were significantly diminished, while concentrations of thyrotropin-releasing hormone (TRH), thyroid-stimulating hormone (TSH) or free tri-iodothyronine (fT3) were not significantly changed. Also, several genes and proteins related to synthesis of steroid hormones were significantly altered. Findings of the present study illustrate that MC-LR can cause endocrine-disrupting effects through the disruption of synthesis and secretion of hormones along the HPA, HPG and HPT axes and negative feedback regulation. Also, there could be crosstalk among HPA, HPG and HPT axes. These findings elucidate mechanisms of endocrine-disrupting effects of MCs.

Clinical Spectrum of USP8 Pathogenic Variants in Cushing's Disease

Cushing's disease (CD) is a life-threatening condition with a challenging diagnostic process and scarce treatment options. CD is caused by usually benign adrenocorticotrophic hormone (ACTH)-secreting pituitary neuroendocrine tumors (PitNETs), known as corticotropinomas. These tumors are predominantly of sporadic origin, and usually derive from the monoclonal expansion of a mutated cell. Somatic activating variants located within a hotspot of the USP8 gene are present in 11-62% of corticotropinomas, making USP8 the most frequent genetic driver of corticotroph neoplasia. In contrast, other somatic defects such as those affecting the glucocorticoid receptor gene (NR3C1), the BRAF oncogene, the deubiquitinase-encoding gene USP48, and TP53 are infrequent. Moreover, patients with familial tumor syndromes, such as multiple endocrine neoplasia, familial isolated pituitary adenoma, and DICER1 rarely develop corticotropinomas. One of the main molecular alterations in USP8-driven tumors is an overactivation of the epidermal growth factor receptor (EGFR) signaling pathway, which induces ACTH production. Hotspot USP8 variants lead to persistent EGFR overexpression, thereby perpetuating the hyper-synthesis of ACTH. More importantly, they condition a characteristic transcriptomic signature that might be useful for the clinical prognosis of patients with CD. Nevertheless, the clinical phenotype associated with USP8 variants is less well defined. Hereby we discuss the current knowledge on the molecular pathogenesis and clinical picture associated with USP8 hotspot variants. We focus on the potential significance of the USP8 mutational status for the design of tailored clinical strategies in CD.

The recovery time of hypothalamic-pituitary-adrenal axis after curative surgery in Cushing's disease and its related factor

PURPOSE

Patients with Cushing's disease (CD) experienced transient central adrenal insufficiency (CAI) after successful surgery. However, the reported recovery time of hypothalamic-pituitary-adrenal (HPA) axis varied and the related factors which could affect recovery time of HPA axis had not been extensively studied. This study aimed to analyze the duration of CAI and explore the factors affecting HPA axis recovery in post-operative CD patients with biochemical remission.

METHODS

Medical records of diagnosis with CD in Huashan Hospital were reviewed between 2014 and 2020. 140 patients with biochemical remission and regular follow-up after surgery were enrolled in this retrospective cohort study according to the criteria. Demographic details, clinical and biochemical information at baseline and each follow-up (within 2 years) were collected and analyzed.

RESULTS

Overall, 103 patients (73.6%) recovered from transient CAI within 2 years follow-up and the median recovery time was 12 months [95% confidence intervals (CI): 10-14]. The age was younger and midnight ACTH at baseline was significantly lower, while the TT3 and FT3 levels were significantly higher in patients with recovered HPA compared to patients with persistent CAI at 2-year follow-up (p < 0.05). In persistent CAI group, more patients underwent partial hypophysectomy. TT3 at diagnosis was an independent related factor of the recovery of HPA axis, even after adjusting for gender, age, duration, surgical history, maximum tumor diameter, surgical strategy, and postoperative nadir serum cortisol level (p = 0.04, OR: 6.03, 95% CI: 1.085, 22.508). Among patients with unrecovered HPA axis at 2-year follow-up, 23 CAI patients (62%) were accompanied by multiple pituitary axis dysfunction besides HPA axis, including hypothyroidism, hypogonadism, or central diabetes insipidus.

CONCLUSION

HPA axis recovered in 73.6% of CD patients within 2 years after successful surgery, and the median recovery time was 12 months. TT3 level at diagnosis was an independent related factor of postoperative recovery of HPA axis in CD patients. Moreover, patients coexisted with other hypopituitarism at 2-year follow-up had a high probability of unrecovered HPA axis.

The Thyroid Hormone Axis and Female Reproduction

Thyroid function affects multiple sites of the female hypothalamic-pituitary gonadal (HPG) axis. Disruption of thyroid function has been linked to reproductive dysfunction in women and is associated with menstrual irregularity, infertility, poor pregnancy outcomes, and gynecological conditions such as premature ovarian insufficiency and polycystic ovarian syndrome. Thus, the complex molecular interplay between hormones involved in thyroid and reproductive functions is further compounded by the association of certain common autoimmune states with disorders of the thyroid and the HPG axes. Furthermore, in prepartum and intrapartum states, even relatively minor disruptions have been shown to adversely impact maternal and fetal outcomes, with some differences of opinion in the management of these conditions. In this review, we provide readers with a foundational understanding of the physiology and pathophysiology of thyroid hormone interactions with the female HPG axis. We also share clinical insights into the management of thyroid dysfunction in reproductive-aged women.

Thyroid diseases in patients with active endogenous Cushing’s syndrome

Objective: Data about the impact of Cushing’s syndrome (CS) on thyroid is scarce. We aimed to identify the prevalence of thyroid diseases in patients with CS. Patients and Methods: Nineteen patients with CS and 40 healthy participants were included in the study. All patients were tested for free tri-iodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), anti-thyroglobulin (anti-Tg), and antithyroid peroxidase (anti-TPO) levels, and thyroid ultrasonography (US). Results: Overt hypothyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism was evident in 5.3%, 5.3%, and 21.1% of patients with CS; and 2.5%, 7.5%, and 15% of healthy subjects, respectively. fT3 and fT4 levels were lower in patients with CS. None of the patients with CS and 27.5% of the control group had autoimmune thyroid disease (AITD), which was demonstrated by both US findings and anti-TPO positivity (P=0.01). Frequency of thyroid nodule was 52.6% and 52.5% in patients with CS and controls, respectively (P=0.99). Conclusion: The prevalence of thyroid dysfunction, nodular thyroid disease, and goiter is comparable to healthy population. However, AITD is less prevalent among patients with CS. Although, hypercortisolism has an impact on hypothalamic-hypophyseal-thyroid axis, its clinical implication does not seem to be significant.

Differences in thyroid function tests after administration of a single supraphysiological dose of ACTH or a high dose of a synthetic steroid

OBJECTIVE

Although the suppressive action of synthetic steroids on the hypothalamus-pituitary-thyroid (HPT) axis is established, little is known regarding the effect of the administration of synthetic adrenocorticotropic hormone (ACTH).

DESIGN

In the context of a randomized, open label, comparative study assessing the efficacy and safety of ACTH and betamethasone in the treatment of hospitalized patients with acute gout, we compared the effects of these agents on thyroid function tests.

METHODS

Serum TSH, total T4 and T3 and cortisol were measured before and at 24 and 48 h after a single intramuscular dose of synthetic ACTH (1 mg) or betamethasone (6 mg), in 38 hospitalized patients with acute gout and normal thyroid function.

RESULTS

The final analysis included 32 patients, due to missing data. The ACTH and betamethasone groups did not differ regarding the mean age, gender, severity of gout attack, and baseline thyroid parameters. In the ACTH group TSH and T4 were significantly decreased at 24 and at 48 h compared to baseline, while T3 was decreased at 24 but not at 48 h. In the betamethasone group T3 remained stable; TSH and T4 decreased significantly from baseline levels at 24 h; at 48 h, TSH had returned to and T4 showed a partial rebound towards pre-treatment values.

CONCLUSIONS

A single IM administration of 1 mg of synthetic ACTH has more profound and prolonged effects on the HPT axis, lasting for at least 48 h, compared to a single IM dose of 6 mg betamethasone.

Pancreatic neuroendocrine tumor with ectopic adrenocorticotropic hormone syndrome: a case report and 5-year follow-up

Pancreatic neuroendocrine tumors (P-NETs) secreting ectopic adrenocorticotropic hormones (ACTH) are rare and often delayed in diagnosis due to their atypical clinical characteristics. Here, we describe a case of P-NET in the pancreatic tail. The tumor had metastasized to the liver and secreted gastrin and ACTH. A 60-year-old female patient was diagnosed with gastrinoma in the pancreatic tail with liver metastases in 2015. After 3 months, the patient presented refractory hypokalemia and thyroid dysfunction. The final diagnosis was P-NET with ectopic ACTH syndrome (EAS). After cytoreductive surgery and the use of long-acting somatostatin analogs, plasma potassium levels and thyroid function were effectively corrected. Although Sandostatin LAR^® Depot and proton pump inhibitors (PPIs) were used throughout the follow-up period, the tumor relapsed 4 years later. After aggressive treatment, including right hepatectomy, microwave coagulation of the left liver, and cholecystectomy, the tumor returned 4 months later. Finally, the patient underwent three hepatic artery embolizations and 12 courses of CAPTEM regimen chemotherapy. The markers of disease were almost maintained in the normal ranges until now. We have followed up on this case for more than 5 years. A timely and comprehensive examination of hormones and immunohistochemistry is essential. The prognosis of P-NET is poor. Regular long-term follow-up and the application of combined therapies are helpful to control the disease and improve the prognosis.

Epidemiology of Male Hypogonadism

The epidemiology of male hypogonadism has been understudied. Of the known causes of endogenous androgen deficiency, only Klinefelter syndrome is common with a likely population prevalence of greater than 5:10,000 men (possibly as high as 10-25:10,000). Mild traumatic injury might also be a common cause of androgen deficiency (prevalence 5-10:10,000 men), but large, long-term studies must be completed to confirm this prevalence estimation that might be too high. The classic causes of male androgen deficiency-hyperprolactinemia, pituitary macroadenoma, endogenous Cushing syndrome, and iron overload syndrome-are rare (prevalence < 10,000 men).

Perioperative Management of a Patient with Cushing’s Disease

Patients with Cushing’s disease (CD) may present with both chronic and acute perioperative complications that necessitate multidisciplinary care. This review highlights several objectives for these patients before and after transsphenoidal surgery. Preoperative management includes treatment of electrolyte disturbances, cardiovascular comorbidities, prediabetes/diabetes, as well as prophylactic consideration(s) for thromboembolism and infection(s). Preoperative medical therapy (PMT) could prove beneficial in patients with severe hypercortisolism or in cases of delayed surgery. Some centers use PMT routinely, although the clinical benefit for all patients is controversial. In this setting, steroidogenesis inhibitors are preferred because of rapid and potent inhibition of cortisol secretion. If glucocorticoids are not used perioperatively, an immediate remission assessment postoperatively is possible. However, perioperative glucocorticoid replacement is sometimes necessary for clinically unstable or medically pretreated patients and for those patients with surgical complications. A nadir serum cortisol &lt; 2-5µg/dl during 24-74 hours postoperatively is generally accepted as remission; higher values suggest non-remission, while a few patients may display delayed remission. If remission is not achieved, additional treatments are pursued. The early postoperative period necessitates multidisciplinary awareness for early diagnosis of adrenal insufficiency (AI) to avoid adrenal crisis, which may be also potentiated by acute postoperative complications. Preferred glucocorticoid replacement is hydrocortisone, if available. Assessment of recovery from postoperative AI should be undertaken periodically. Other postoperative targets include decreasing antihypertensive/diabetic therapy if in remission, thromboprophylaxis, infection prevention/treatment, and management of electrolyte disturbances and/or potential pituitary deficiencies. Evaluation of recovery of thyroid, gonadal and growth hormone deficiencies should be also performed in the following months postoperatively.

Disruption by stealth - Interference of endocrine disrupting chemicals on hormonal crosstalk with thyroid axis function in humans and other animals

Thyroid hormones (THs) are important regulators of growth, development, and homeostasis of all vertebrates. There are many environmental contaminants that are known to disrupt TH action, yet their mechanisms are only partially understood. While the effects of Endocrine Disrupting Chemicals (EDCs) are mostly studied as "hormone system silos", the present critical review highlights the complexity of EDCs interfering with TH function through their interactions with other hormonal axes involved in reproduction, stress, and energy metabolism. The impact of EDCs on components that are shared between hormone signaling pathways or intersect between pathways can thus extend beyond the molecular ramifications to cellular, physiological, behavioral, and whole-body consequences for exposed organisms. The comparatively more extensive studies conducted in mammalian models provides encouraging support for expanded investigation and highlight the paucity of data generated in other non-mammalian vertebrate classes. As greater genomics-based resources become available across vertebrate classes, better identification and delineation of EDC effects, modes of action, and identification of effective biomarkers suitable for HPT disruption is possible. EDC-derived effects are likely to cascade into a plurality of physiological effects far more complex than the few variables tested within any research studies. The field should move towards understanding a system of hormonal systems' interactions rather than maintaining hormone system silos.

Consensus on diagnosis and management of Cushing's disease: a guideline update

Cushing's disease requires accurate diagnosis, careful treatment selection, and long-term management to optimise patient outcomes. The Pituitary Society convened a consensus workshop comprising more than 50 academic researchers and clinical experts to discuss the application of recent evidence to clinical practice. In advance of the virtual meeting, data from 2015 to present about screening and diagnosis; surgery, medical, and radiation therapy; and disease-related and treatment-related complications of Cushing's disease summarised in recorded lectures were reviewed by all participants. During the meeting, concise summaries of the recorded lectures were presented, followed by small group breakout discussions. Consensus opinions from each group were collated into a draft document, which was reviewed and approved by all participants. Recommendations regarding use of laboratory tests, imaging, and treatment options are presented, along with algorithms for diagnosis of Cushing's syndrome and management of Cushing's disease. Topics considered most important to address in future research are also identified.

Cushing's Syndrome Effects on the Thyroid

The most known effects of endogenous Cushing’s syndrome are the phenotypic changes and metabolic consequences. However, hypercortisolism can exert important effects on other endocrine axes. The hypothalamus–pituitary–thyroid axis activity can be impaired by the inappropriate cortisol secretion, which determinates the clinical and biochemical features of the “central hypothyroidism”. These findings have been confirmed by several clinical studies, which also showed that the cure of hypercortisolism can determine the recovery of normal hypothalamus–pituitary–thyroid axis activity. During active Cushing’s syndrome, the “immunological tolerance” guaranteed by the hypercortisolism can mask, in predisposed patients, the development of autoimmune thyroid diseases, which increases in prevalence after the resolution of hypercortisolism. However, the immunological mechanism is not the only factor that contributes to this phenomenon, which probably includes also deiodinase-impaired activity. Cushing’s syndrome can also have an indirect impact on thyroid function, considering that some drugs used for the medical control of hypercortisolism are associated with alterations in the thyroid function test. These considerations suggest the utility to check the thyroid function in Cushing’s syndrome patients, both during the active disease and after its remission.