Best practice & research. Clinical endocrinology & metabolism最新文献

GH-secreting tumors represent 15 % to 20 % of all pituitary neuroendocrine tumors (pitNETs), of which 95 % occur in a sporadic context, without an identifiable inherited cause. Recent multi-omic approaches have characterized the epigenomic, genomic, transcriptomic, proteomic and kynomic landscape of pituitary tumors. Transcriptomic analysis has allowed us to discover specific transcription factors driving the differentiation of pituitary tumors and gene expression patterns. GH-secreting, along with PRL- and TSH-secreting pitNETs are driven by POU1F1; ACTH-secreting tumors are determined by TBX19; and non-functioning tumors, which are predominantly of gonadotrope differentiation are conditioned by NR5A1. Upregulation of certain miRNAs, such as miR-107, is associated with tumor progression, while downregulation of others, like miR-15a and miR-16–1, correlates with tumor size reduction. Additionally, miRNA expression profiles are linked to treatment resistance and clinical outcomes, providing insights into potential therapeutic targets. Specific somatic mutations in GNAS, PTTG1, GIPR, HGMA2, MAST and somatic variants associated with cAMP, calcium signaling, and ATP pathways have also been associated with the development of acromegaly. This review focuses on the oncogenic mechanisms by which sporadic acromegaly can develop, covering a complex series of molecular alterations that ultimately alter the balance between proliferation and apoptosis, and dysregulated hormonal secretion.

Ectopic acromegaly is a rare condition caused by extrapituitary central or peripheral neuroendocrine tumours (NET) that hypersecrete GH or, more commonly, GHRH. It affects less than 1% of acromegaly patients and a misdiagnosis of classic acromegaly can lead to an inappropriate pituitary surgery. Four types of ectopic acromegaly have been described: 1) Central ectopic GH-secretion: Careful cross-sectional imaging is required to exclude ectopic pituitary adenomas. 2) Peripheral GH secretion: Extremely rare. 3) Central ectopic GHRH secretion: Sellar gangliocytomas immunohistochemically positive for GHRH are found after pituitary surgery. 4) Peripheral GHRH secretion: The most common type of ectopic acromegaly is due to peripheral GHRH-secreting NETs. Tumours are large and usually located in the lungs or pancreas. Pituitary hyperplasia resulting from chronic GHRH stimulation is difficult to detect or can be misinterpreted as pituitary adenoma in the MRI. Measurement of serum GHRH levels is a specific and useful diagnostic tool. Surgery of GHRH-secreting NETs is often curative.

Vitamin D is mainly produced in the skin (cholecalciferol) by sun exposure while a fraction of it is obtained from dietary sources (ergocalciferol). Vitamin D is further processed to 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D (calcitriol) in the liver and kidneys, respectively. Calcitriol is the active form which mediates the actions of vitamin D via vitamin D receptor (VDR) which is present ubiquitously. Defect at any level in this pathway leads to vitamin D deficient or resistant rickets. Nutritional vitamin D deficiency is the leading cause of rickets and osteomalacia worldwide and responds well to vitamin D supplementation. Inherited disorders of vitamin D metabolism (vitamin D-dependent rickets, VDDR) account for a small proportion of calcipenic rickets/osteomalacia. Defective 1α hydroxylation of vitamin D, 25 hydroxylation of vitamin D, and vitamin D receptor result in VDDR1A, VDDR1B and VDDR2A, respectively whereas defective binding of vitamin D to vitamin D response element due to overexpression of heterogeneous nuclear ribonucleoprotein and accelerated vitamin D metabolism cause VDDR2B and VDDR3, respectively. Impaired dietary calcium absorption and consequent calcium deficiency increases parathyroid hormone in these disorders resulting in phosphaturia and hypophosphatemia. Hypophosphatemia is a common feature of all these disorders, though not a sine-qua-non and leads to hypomineralisation of the bone and myopathy. Improvement in hypophosphatemia is one of the earliest markers of response to vitamin D supplementation in nutritional rickets/osteomalacia and the lack of such a response should prompt evaluation for inherited forms of rickets/osteomalacia.

Premature ovarian insufficiency (POI) is a condition in which there is a decline in ovarian function in women who are younger than 40 years resulting in a hypo-oestrogenic state with elevated gonadotrophins and oligomenorrhoea/amenorrhoea. This leads to short term complications of menopausal symptoms and long-term effects on bone and cardiovascular health, cognition as well as the impact of reduced fertility and sexual function associated with this condition. It is managed by sex steroid replacement either with HRT or combined hormonal contraception until the age of natural menopause (51) and this can provide a beneficial role with both symptom control and minimising the long-term adverse effects associated with this condition. Women who undergo a menopause between 40 and 45 years are deemed to have an “early menopause”. The limited data available for this group suggest that they also have an increased morbidity if not adequately treated with hormone therapy. As such, women who have an early menopause should be managed in a similar way to those with POI, with the recommendation that they should take HRT at least until the natural age of menopause. This is the same for induced menopause that is caused by medical or surgical treatment that impacts the ovaries. It is important to ensure early diagnosis and access to specialist care to help support and manage these patients to reduce the symptoms and risks of long-term complications. This review looks at the diagnosis, causes, short and long-term complications and management of POI, early and induced menopause.

Estrogen depletion following menopause predisposes to increased risk of cardiovascular disease (CVD), mainly due to ischemic heart disease. This is mostly evident in cases with premature menopause. The pathophysiological basis for this atherosclerotic process is the accumulation of several risk factors, such as abdominal obesity, atherogenic dyslipidemia, insulin resistance and arterial hypertension. The presence of vasomotor symptoms may further augment this risk, especially in women younger than 60 years. Menopausal hormone therapy (MHT) exerts many beneficial effects on lipid profile and glucose homeostasis as well as direct arterial effects, and may reduce CVD risk if initiated promptly (i.e.,<60 years or within ten years of the final menstrual period). Transdermal estradiol and micronized progesterone or dydrogesterone are the safest regimens in terms of venous thromboembolic events (VTE) and breast cancer risk. In any case, an individualized approach, taking into account the patient’s total CVD, VTE and breast cancer risk, is recommended.

The menopause transition is usually a gradual process occurring over many years, caused by the cessation of ovarian reproductive function, resulting in the end of menstrual bleeding. In the peri-menopause, ovarian function and therefore the production of the hormones oestrogen, progesterone and testosterone can fluctuate greatly, leading to a wide variety of symptoms, affecting multiple organ systems. Menopause and the management of its associated symptoms can be very challenging for patients and clinicians alike and can negatively impact quality of life. The management options include lifestyle adjustment, talking therapies, dietary supplements as well as prescribed medications, including hormone replacement therapy. The UK’s average life expectancy for women is approximately 81 years. Therefore, women will now live up to a third of their life being either peri- or postmenopausal. Thus, understanding and treating, where possible, the symptoms of menopause is essential to reduce the burden associated with this physiological state.

Women are living a significant portion of their adult lives in the post-reproductive phase, and many seek help for debilitating menopausal symptoms. Every individual’s experience of menopausal transition is unique. Adopting a holistic approach to managing the menopause using a combination of lifestyle, hormonal, and non-hormonal interventions is key to maximise the quality of life of affected women. However, many opt to use non hormonal options or have contraindications to using hormonal therapy. Studies have shown that several pharmacological non-hormonal medications such as SSRIs, SSRI/SNRIs, Gabapentin, and Pregabalin are effective for managing vasomotor symptoms as well as other menopausal symptoms. Their main side effects are dry mouth, nausea, constipation, reduced libido, and loss of appetite. Clonidine is the only non-hormonal drug which is licenced for control of vasomotor symptoms in the UK, but has several side effects including dizziness and sleep disturbance. Cognitive Behavioural Therapy is recommended as a treatment for anxiety, sleep problems and vasomotor symptoms related to menopausal transition. Evidence for clinical efficacy and safety of herbal remedies and alternative therapies remains weak. Studies with neurokinin receptor 3 antagonists on women with hot flushes have shown improvement in vasomotor symptoms and results of large-scale studies are awaited.

Vasomotor symptoms (VMS) are characteristic of menopause experienced by over 75% of postmenopausal women with significant health and socioeconomic implications. Although the average duration of symptoms is seven years, 10% of women experience symptoms for more than a decade. Although menopausal hormone therapy (MHT) remains an efficacious and cost-effective treatment, its use may not be suitable in all women, such as those at an increased risk of breast cancer or gynaecological malignancy. The neurokinin B (NKB) signaling pathway, together with its intricate connection to the median preoptic nucleus (MnPO), has been postulated to provide integrated reproductive and thermoregulatory responses, with a central role in mediating postmenopausal VMS. This review describes the physiological hypothalamo-pituitary-ovary (HPO) axis, and subsequently the neuroendocrine changes that occur with menopause using evidence derived from animal and human studies. Finally, data from the latest clinical trials using novel therapeutic agents that antagonise NKB signaling are reviewed.