Does hypoleptinemia trigger entrapment in anorexia nervosa? Etiological and clinical considerations

Based on the recent observation that human recombinant leptin (r-Met-hu-leptin; metreleptin) may induce a profound alleviation of the complex symptomatology of patients with anorexia nervosa (AN), we examine the implications for our conceptualisation of this eating disorder. Hypoleptinemia as a core endocrine feature of AN serves as a central and peripheral trigger of tissue-specific adaptations to starvation. In this narrative review, we argue that leptin deficiency may explain many of the puzzling features of this eating disorder. Weight loss can be viewed as a two-step process, with only the second step entailing hypoleptinemia and thereby the entrapment characteristic of AN. We discuss the central and peripheral distribution of leptin receptors and consider possible functional implications of hypoleptinemia. We contrast the slow psychological recovery of patients with AN and of people who experienced starvation upon weight recovery with the rapid onset of improvements upon off-label metreleptin treatment. Characteristics of the sex and age dependent secretion of leptin may contribute to the elevated vulnerability of young females to develop AN.

The Exon 3-Deleted Growth Hormone Receptor (d3GHR) Polymorphism-A Favorable Backdoor Mechanism for the GHR Function

Growth hormone (GH) is a peptide hormone that plays a crucial role in controlling growth, development, and lifespan. Molecular regulation of GH is accomplished via the GH receptor (GHR), which is the main factor influencing human development and is essential to optimal functioning of the GH/IGF-I axis. Two GHR isoforms have been studied, according to the presence (flGHR) or absence (d3GHR) of exon 3. The d3GHR isoform, which lacks exon 3 has recently been related to longevity; individuals carrying this isoform have higher receptor activity, improved signal transduction, and alterations in the treatment response and efficacy compared with those carrying the wild type (WT) isoform (flGHR). Further, studies performed in patients with acromegaly, Prader-Willi syndrome, Turner syndrome, small for gestational age (SGA), and growth hormone deficiency (GHD) suggested that the d3GHR isoform may have an impact on the relationship between GH and IGF-I levels, height, weight, BMI, and other variables. Other research, however, revealed inconsistent results, which might have been caused by confounding factors, including limited sample sizes and different experimental methods. In this review, we lay out the complexity of the GHR isoforms and provide an overview of the major pharmacogenetic research conducted on this ongoing and unresolved subject.

Screening for possible hypopituitarism following mild traumatic brain injury: The first all-female study. Who do we need to evaluate further?

BACKGROUND

Studies on hypopituitarism (HP) following mild traumatic brain injury (mTBI) have focused on male populations although women may be more susceptible to the sequelae of mTBI. This is, to the best of our knowledge, the first all-female study screening for HP following mTBI.

OBJECTIVE

Screening for possible HP in female athletes reporting a history of one or more mTBI.

METHODS

Pituitary hormone screening blood tests (SBT) were performed in 133 of the 151 female athletes included. Repeated results outside the reference value (O-RV) were considered abnormal necessitating further endocrinological evaluation.

RESULTS

Repeated SBT were O-RV in 88 women (66.2%). Decreased levels of serum insulin growth factor 1 (S-IGF1) were found in 55.6% of participants and elevated levels of serum prolactin (S-prolactin) in 22.6%. Serum cortisol levels were below the RV in 6.0% and thyroid hormonal levels in 11.3%. Lower age and increased number of mTBI symptoms correlated significantly with the risk of hormonal results O-RV.

CONCLUSION

The majority of the study population had SBT O-RV, warranting further workup of possible HP. Decreased levels of S-IGF1 were most commonly observed followed by elevated S-prolactin possibly indicating hypothalamic-pituitary impairment. Lower age and increased number of symptoms of mTBI may indicate the need to screen for HP.

The late effects of cranial irradiation in childhood on the hypothalamic-pituitary axis: a radiotherapist's perspective

Brain tumours make up nearly one-third of paediatric malignancies. Over time, advancements in oncological treatments like radiotherapy have helped reduce normal-tissue toxicity when treating cancers in the brain. However, clinicians are still facing a trade-off between treatment efficacy and potential side effects. The aim of this review is to address the late effects of cranial irradiation on the neuroendocrine system and to identify factors that make patients more vulnerable to radiation-induced endocrine sequelae. Radiation damage to the hypothalamic-pituitary axis, which orchestrates hormone release, can lead to endocrinopathy; up to 48.8% of children who have undergone cranial irradiation develop a hormone deficiency. This may lead to further health complications that can appear up to decades after the last treatment, lowering the patients' quality of life and increasing long-term costs as lifelong hormone replacement therapy may be required. Growth hormone deficiency is the most common sequelae, followed by either thyroid or gonadotropic hormone deficiency. Adrenocorticotropic hormone deficiency tends to be the least common. Identified factors that increase the risk of late endocrine deficiency include total radiation dose, age at treatment, and time since last treatment. However, as there are various other factors that may potentiate the damage, a universal solution proven to be most effective in sparing the endocrine tissues is yet to be identified. Until then, accounting for the identified risk factors during treatment planning may in some cases help reduce the development of endocrine sequelae in childhood cancer survivors.

Perioperative fluctuation and overall evaluation of adenohypophyseal hormone secretion in patients with nonfunctioning pituitary adenoma

OBJECTIVE

Perioperative adenohypophyseal hormone assessment can improve therapeutic strategies and be used to evaluate the prognosis of pituitary adenomas. An individual hormone level does not entirely reflect the pituitary gland. Thus, this study aimed to analyze perioperative hormonal changes and propose a normalized method to facilitate overall assessment of the adenohypophysis.

METHODS

The authors retrospectively analyzed 89 male patients with nonfunctioning pituitary adenoma (NFPA) who underwent transsphenoidal surgery. Preoperative clinical data, imaging data, and perioperative hormone levels of the anterior pituitary gland were evaluated. Hormone values were rescaled using minimum-maximum normalization. The sum of the normalized hormone levels was defined as the total hormonal rate (THR).

RESULTS

Preoperative findings indicated correlations among different adenohypophyseal hormones. Luteinizing hormone (p = 0.62) and adrenocorticotropic hormone (p = 0.89) showed no significant changes after surgery, but growth hormone levels increased (p < 0.001). On the contrary, the levels of thyroid-stimulating hormone (p < 0.001), follicle-stimulating hormone (p = 0.02), and prolactin (p < 0.001) decreased. THR indicated a significant postoperative reduction in adenohypophyseal function (p = 0.04). Patients with postoperative hypopituitarism had significantly lower THR than those without (p = 0.003), with an area under the curve of 0.66. For NFPAs that presented with normal preoperative hormone levels, THR was a good clinical predictor of immediate postoperative hypopituitarism, with an area under the curve of 0.74.

CONCLUSIONS

The normalized synthesis index of hormones is a novel and clinically valuable method used to reflect adenohypophyseal secretion. Compared with individual hormones, these results indicated that THR can facilitate the analysis of general hormone levels despite various fluctuations in adenohypophyseal hormones. THR may also contribute to the effective prediction of short-term surgery-induced hypopituitarism.

Pituitary Apoplexy: A Retrospective Study of 33 Cases From a Single Center

PURPOSE

Acute symptomatic pituitary apoplexy is a rare and potentially life-threatening condition. However, pituitary apoplexy can also present with milder symptoms and stable hemodynamics. Due to the rarity of this inhomogeneous condition, clinical studies are important to increase the knowledge.

METHODS

We retrospectively reviewed all consecutive cases of pituitary apoplexy being admitted between January 1^st, 2005 and December 31^st, 2019 at the Karolinska University Hospital, Stockholm, Sweden, for symptoms, results of magnetic resonance (MRI), biochemistry, management and mortality.

RESULTS

Thirty-three patients were identified with pituitary apoplexy, 18 were men (55%) and mean age was 46.5 (17.2) years. The incidence of symptomatic pituitary apoplexy was 1.6 patients/year (0.76 patients/1,000,000 inhabitants/year). The majority presented with headache (n=27, 82%) and hormonal deficiencies (n=18, 55%), which were most frequent in men. ACTH deficiency was present in nine patients (27% but 50% of those with hormonal deficiencies). All had the characteristic findings on MRI. Only three patients (9%) required acute pituitary surgery, while eight were operated after more than one week. Seven (21%) were on antithrombotic therapy. None of the patients died in the acute course. During follow-up (7.6 ± 4.3 years) none of the hormonal deficiencies regressed and 3 patients died from non-related causes.

CONCLUSION

Our study confirmed the rarity and the symptoms of this condition. Surprisingly, only 3 patients needed acute neurosurgical intervention, perhaps due to milder cases and a general intensified treatment of precipitating factors. An early awareness and in severe cases decision on pituitary surgery is of utmost importance to avoid severe complications.

Epidemiology, natural history, and optimal management of neurohypophyseal germ cell tumors

OBJECTIVE

Intracranial germ cell tumors (iGCTs) often arise at the neurohypophysis, their second most common origination, following the pineal region. Neurohypophyseal iGCTs present with stereotypical symptoms, including pituitary dysfunction and visual field deficit, due to their suprasellar location. The goal of this study was to present a large, longitudinal single-institution experience with neurohypophyseal iGCTs to better understand their natural history and identify opportunities for further improvement in treatment outcomes.

METHODS

This is a retrospective, single-institution cohort study of neurohypophyseal iGCTs treated between 1988 and 2017, with a focus on the epidemiology, presentation, natural history, and treatment.

RESULTS

Thirty-five neurosurgically managed patients met inclusion criteria; the median age was 18 years (3 months to 49 years), and 74% of patients were male (n = 26). Thirty-one tumors were germinomas, and 4 were nongerminomatous iGCTs. Presenting symptoms included pituitary insufficiency in 76% (n = 25), visual deficit in 45% (n = 15), and diabetes insipidus (DI) in 61% (n = 20) of patients. Index symptoms included isolated DI in 10 (36%), isolated hormone deficiency in 14 (50%), and concomitant DI and hormone deficiency symptoms in 4 (14%). Radiographic diagnostic latency was common, occurring at a median of 363 days (range 9-2626 days) after onset of the first symptoms and was significantly associated with both DI and hormone deficiency as the index symptoms (no DI vs DI: 360 vs 1083 days, p = 0.009; no hormone deficiency vs hormone deficiency: 245 vs 953 days, p = 0.004). Biochemical abnormalities were heterogeneous; each pituitary axis was dysfunctional in at least 1 patient, with most patients demonstrating at least 2 abnormalities, and pretreatment dysfunction demonstrating a nonsignificant trend toward association with long-term posttreatment hormone supplementation. Among germinomas, whole-brain or whole-ventricle radiotherapy demonstrated significantly improved progression-free and overall survival compared with local therapy (p = 0.009 and p = 0.004, respectively).

CONCLUSIONS

Neurohypophyseal iGCTs are insidious tumors that may pose a diagnostic dilemma, as evidenced by the prolonged latency before radiographic confirmation. Serial imaging and close endocrine follow-up are recommended in patients with a characteristic clinical syndrome and negative imaging, due to the propensity for radiographic latency. Pretreatment biochemical abnormalities may indicate higher risk of posttreatment pituitary insufficiency, and all patients should receive careful endocrine follow-up. Local radiotherapy is prone to treatment failure, while whole-ventricle treatment is associated with improved survival in germinomas.

Microencapsulation of porcine thyroid cell organoids within a polymer microcapsule construct

Hypothyroidism is a common condition of hormone deficiency, and oral administration of thyroid hormones is currently the only available treatment option. However, there are some disadvantages with this treatment modality including compliance challenges to patients. Therefore, a physiologically based alternative therapy for hypothyroidism with little or no side-effects is needed. In this study, we have developed a method for microencapsulating porcine thyroid cells as a thyroid hormone replacement approach. The hybrid wall of the polymer microcapsules permits thyroid hormone release while preventing immunoglobulin antibodies from entry. This strategy could potentially enable implantation of the microcapsule organoids containing allogeneic or xenogeneic thyroid cells to secret hormones over time without the need for immunosuppression of recipients. Porcine thyroid cells were isolated and encapsulated in alginate-poly-L-ornithine-alginate microcapsules using a microfluidic device. The porcine thyroid cells formed three-dimensional follicular spheres in the microcapsules with decent cell viability and proliferation. Thyroxine release from the encapsulated cells was higher than from unencapsulated cells ( P < 0.05) and was maintained during the entire duration of experiment (>28 days). These results suggest that the microencapsulated thyroid cell organoids may have the potential to be used for therapy and/or drug screening.

Narrative review: the role of leptin in human physiology: emerging clinical applications

Leptin is a hormone secreted by adipose tissue in direct proportion to amount of body fat. The circulating leptin levels serve as a gauge of energy stores, thereby directing the regulation of energy homeostasis, neuroendocrine function, and metabolism. Persons with congenital deficiency are obese, and treatment with leptin results in dramatic weight loss through decreased food intake and possible increased energy expenditure. However, most obese persons are resistant to the weight-reducing effects of leptin. Recent studies suggest that leptin is physiologically more important as an indicator of energy deficiency, rather than energy excess, and may mediate adaptation by driving increased food intake and directing neuroendocrine function to converse energy, such as inducing hypothalamic hypogonadism to prevent fertilization. Current studies investigate the role of leptin in weight-loss management because persons who have recently lost weight have relative leptin deficiency that may drive them to regain weight. Leptin deficiency is also evident in patients with diet- or exercise-induced hypothalamic amenorrhea and lipoatrophy. Replacement of leptin in physiologic doses restores ovulatory menstruation in women with hypothalamic amenorrhea and improves metabolic dysfunction in patients with lipoatrophy, including lipoatrophy associated with HIV or highly active antiretroviral therapy. The applications of leptin continue to grow and will hopefully soon be used therapeutically.

Human and mouse TPIT gene mutations cause early onset pituitary ACTH deficiency

Tpit is a highly cell-restricted transcription factor that is required for expression of the pro-opiomelanocortin (POMC) gene and for terminal differentiation of the pituitary corticotroph lineage. Its exclusive expression in pituitary POMC-expressing cells has suggested that its mutation may cause isolated deficiency of pituitary adrenocorticotropin (ACTH). We now show that Tpit-deficient mice constitute a model of isolated ACTH deficiency (IAD) that is very similar to human IAD patients carrying TPIT gene mutations. Through genetic analysis of a panel of IAD patients, we show that TPIT gene mutations are associated at high frequency with early onset IAD, but not with juvenile forms of this deficiency. We identified seven different TPIT mutations, including nonsense, missense, point deletion, and a genomic deletion. This work defines congenital early onset IAD as a relatively homogeneous clinical entity caused by recessive transmission of loss-of-function mutations in the TPIT gene.