Evolving hypopituitarism following cranial irradiation

Cranial irradiation alters neuroinflammation and neural proliferation in the pituitary gland and induces late-onset hormone deficiency

Cranial radiotherapy induces endocrine disorders and reproductive abnormalities, particularly in long-term female cancer survivors, and this might in part be caused by injury to the pituitary gland, but the underlying mechanisms are unknown. The aim of this study was to investigate the influence of cranial irradiation on the pituitary gland and related endocrine function. Female Wistar rat pups on postnatal day 11 were subjected to a single dose of 6 Gy whole-head irradiation, and hormone levels and organ structure in the reproductive system were examined at 20 weeks after irradiation. We found that brain irradiation reduced cell proliferation and induced persistent inflammation in the pituitary gland. The whole transcriptome analysis of the pituitary gland revealed that apoptosis and inflammation-related pathways were up-regulated after irradiation. In addition, irradiation led to significantly decreased levels of the pituitary hormones, growth hormone, adrenocorticotropic hormone, thyroid-stimulating hormone and the reproductive hormones testosterone and progesterone. To conclude, brain radiation induces reduction of pituitary and reproduction-related hormone secretion, this may due to reduced cell proliferation and increased pituitary inflammation after irradiation. Our results thus provide additional insight into the molecular mechanisms underlying complications after head irradiation and contribute to the discovery of preventive and therapeutic strategies related to brain injury following irradiation.

Whole Ovary Cryopreservation and Transplantation: A Systematic Review of Challenges and Research Developments in Animal Experiments and Humans

Ovarian tissue cryopreservation and transplantation is the only fertility preservation option that enables both restoration of fertility and resumption of ovarian endocrine function, avoiding the morbidity associated with premature menopause. It is also the only technique available to prepubertal patients and those whose treatment cannot be delayed for life-threatening reasons. Ovarian tissue cryopreservation can be carried out in two different ways, either as ovarian cortical fragments or as a whole organ with its vascular pedicle. Although use of cortical strips is the only procedure that has been approved by the American Society for Reproductive Medicine, it is fraught with drawbacks, the major one being serious follicle loss occurring after avascular transplantation due to prolonged warm ischemia. Whole ovary cryopreservation involves vascular transplantation, which could theoretically counteract the latter phenomenon and markedly improve follicle survival. In theory, this technique should maintain endocrine and reproductive functions much longer than grafting of ovarian cortical fragments. However, this procedure includes a number of critical steps related to (A) the level of surgical expertise required to accomplish retrieval of a whole ovary with its vascular pedicle, (B) the choice of cryopreservation technique for freezing of the intact organ, and (C) successful execution of functional vascular reanastomosis upon thawing. The aim of this systematic review is to shed light on these challenges and summarize solutions that have been proposed so far in animal experiments and humans in the field of whole ovary cryopreservation and transplantation.

Hypothalamic-pituitary axis irradiation dose thresholds for the development of hypopituitarism in adult-onset gliomas

BACKGROUND

Childhood brain tumour survivors who receive cranial radiotherapy undergo regular surveillance for the development ofhypothalamic-pituitary (HP) axis dysfunction. Much less attention has been given to radiation-induced hypopituitarism in patients with malignant brain tumours of adult onset.

DESIGN

Retrospective cohort study.

PATIENTS/MEASUREMENTS

We assessed the effects of cranial radiotherapy (cXRT) on pituitary function in 58 adults (32 male) with gliomas distant to the HP axis. The XRT dose exposure at the HP axis was correlated with individual axis dysfunction to establish dose thresholds.

RESULTS

Mean age at cXRT was 41.2 ± 10.9 years and duration of endocrine follow-up 8.2 ± 5.2 years. Mean XRT dose to the HP axis was 35.9 ± 15.5 Gy. Overall prevalence of radiation-induced hypopituitarism was 84.5%. GH, LH/FSH, ACTH and TSH deficiency were present in 82.8%, 20.7%, 19% and 6.9% of patients, respectively. Hyperprolactinaemia was noted in 10.3% (n = 6) and was persistent in one case. GH deficiency and "any degree of hypopituitarism" positively correlated with the radiotherapy dose to the hypothalamic-pituitary axis. HP axis XRT dose thresholds for the development of GHD, LH/FSH, ACTH and TSH deficiency were established at 10, 30, 32 and 40.8 Gy, respectively. A gradual increase in the prevalence of all anterior pituitary hormone deficits was observed throughout the follow-up period.

CONCLUSIONS

Hypopituitarism post-cXRT in adults with gliomas is a frequent, progressive and dose-dependent phenomenon. Dose thresholds suggest long-term endocrine surveillance is important where the HP axis XRT dose is higher than 30 Gy. Identification of deficits to allow early and appropriate hormone replacement therapy is important to improve well-being in these individuals with limited prognosis.

Central hypothyroidism - a neglected thyroid disorder

Central hypothyroidism is a rare and heterogeneous disorder that is characterized by a defect in thyroid hormone secretion in an otherwise normal thyroid gland due to insufficient stimulation by TSH. The disease results from the abnormal function of the pituitary gland, the hypothalamus, or both. Moreover, central hypothyroidism can be isolated or combined with other pituitary hormone deficiencies, which are mostly acquired and are rarely congenital. The clinical manifestations of central hypothyroidism are usually milder than those observed in primary hypothyroidism. Obtaining a positive diagnosis for central hypothyroidism can be difficult from both a clinical and a biochemical perspective. The diagnosis of central hypothyroidism is based on low circulating levels of free T₄ in the presence of low to normal TSH concentrations. The correct diagnosis of both acquired (also termed sporadic) and congenital (also termed genetic) central hypothyroidism can be hindered by methodological interference in free T₄ or TSH measurements; routine utilization of total T₄ or T₃ measurements; concurrent systemic illness that is characterized by low levels of free T₄ and normal TSH concentrations; the use of the sole TSH-reflex strategy, which is the measurement of the sole level of TSH, without free T₄, if levels of TSH are in the normal range; and the diagnosis of congenital hypothyroidism based on TSH analysis without the concomitant measurement of serum levels of T₄. In this Review, we discuss current knowledge of the causes of central hypothyroidism, emphasizing possible pitfalls in the diagnosis and treatment of this disorder.

Menstrual restoration in severe panhypopituitarism many years after cranial irradiation for suprasellar germinoma

Purpose

We report a very rare case showing menstrual restoration in severe pan-hypopituitarism many years after cranial irradiation for suprasellar germinoma.

Case

A 30-year-old, almost primarily amenorrheic woman with severe panhypopituitarism presented with cyclic genital bleeding for the previous five months. She had menstruated once, when she was 13 years old. When she was 14 years old, she was diagnosed with a suprasellar germinoma measuring 10 mm in diameter, which led to diabetes insipidus. Cranial irradiation with a total dose of 24 Gy and chemotherapy resulted in complete tumor remission. She developed severe hypopituitarism [luteinizing hormone (LH) = 0.4 mIU/mL, follicle-stimulating hormone (FSH) = 1.7 mIU/mL, and serum estradiol (E2) level < 10 pg/mL]. She had received multiple hormone replacement therapies for many years. When she was 29 years old, she expressed a desire to become pregnant. Serum gonadotropin and E2 levels increased (LH = 5.8 mIU/mL, FSH = 5.9 mIU/mL, and E2 = 58 pg/mL). She conceived with clomiphene therapy, and then delivered a healthy baby. Eight months after parturition, her basal body temperature and serum progesterone levels indicated recovery of ovulatory cycles. Ten months after parturition, she also spontaneously conceived.

Conclusion

Menstrual restoration is very rare in severe panhypopituitarism after cranial irradiation. A relatively low dose of irradiation and small tumor size may have contributed to the recovery of menstruation in our patient.

Clinical review: Central hypothyroidism: pathogenic, diagnostic, and therapeutic challenges

CONTEXT

Central hypothyroidism (CH) is a particular hypothyroid condition due to an insufficient stimulation by TSH of an otherwise normal thyroid gland. This condition raises several challenges for clinicians; therefore, a review of the most relevant findings on CH epidemiology, pathogenesis, and clinical management has been performed.

METHODOLOGY

The relevant papers were selected by a PubMed search using appropriate key words.

MAIN FINDINGS

CH can be the consequence of various disorders affecting either the pituitary gland or the hypothalamus, but most frequently affecting both of them. CH is about 1000-fold rarer than primary hypothyroidism. Except for the neonatal CH due to biallelic TSHβ mutations, the thyroid hormone defect is rarely as profound as can be observed in some primary forms. In contrast with primary hypothyroidism, CH is most frequently characterized by low/normal TSH levels, and adequate thyroid hormone replacement is associated with the suppression of residual TSH secretion. Thus, CH often represents a clinical challenge because physicians cannot rely on the systematic use of the "reflex TSH strategy." The clinical management of CH is further complicated by the frequent combination with other pituitary deficiencies and their substitution.

Time course of hypothalamic-pituitary deficiency in adults receiving cranial radiotherapy for primary extrasellar brain tumors

BACKGROUND

No longitudinal data on hypothalamic-pituitary (HP) function are available in patients who had received cranial radiation therapy (CRT) for primary extrasellar brain tumors (PBT).

PURPOSE

To investigate the effects of CRT on HP function in adults with PBT.

PATIENTS AND METHODS

Twenty-six adults irradiated for PBT and six CRT naive controls were studied. CRT was delivered with 6 MV X-ray by a linear accelerator (2 Gy fraction schedule). Gross Tumor Volume (GTV) excluded the HP region that was contoured on the planning CT. Median dose to the HP region was 41.8 Gy (IQR: 30.7-49.8).

RESULTS

All controls maintained normal HP function. Hypopituitarism developed in 38% of CRT patients (GH deficiency 29%, ACTH 22%, TSH 14%, gonadotropin 4%, no abnormal prolactin level or diabetes insipidus). All HP failures occurred within 32 months after CRT.

CONCLUSIONS

Adults undergoing CRT for PBT are at increased risk for HP dysfunction within 3 years from CRT. Endocrine surveillance is recommended also in adults patients exposed to CRT for primary brain tumors distant from HP region.

Gonadal Function in Patients Treated for Leukemia in Childhood

Ovarian and testicular function were assessed in 67 long-term survivors (37 females, 30 males) treated for leukemia between 1973 and 1992. At diagnosis they were 1-16 (median 5) years old and had evaluation of gonadal function 4-25 (median 13) years later at the age of 13-31 (median 19). All had been treated with various combinations of chemotherapy (ChT) (including cyclophosphamide (CYC) and cytarabine in 32 patients), 62 patients had received prophylactic cranial irradiation with 12-49 (median 18) Gy, 2 patients had had craniospinal irradiation with 24 and 10 Gy respectively. Nine patients were treated for relapse; 2 boys had testicular irradiation (RT) with 12 Gy in 3 fractions and 1 girl whole-abdomen RT with 20 Gy as a part of this treatment. Three patients were treated for second malignancies. Gonadal function was assessed by clinical examination and measurement of serum concentrations of estradiol and testosterone. Serum levels of LH and FSH were determined in basal state and after stimulation. Primary hypogonadism was found in 6 (9%) patients. Five (16,5%) males had primary hypogonadism with evidence of damage to the germinal epithelium, 2 of them, treated with testicular RT, had evidence of damage to the Leydig cells and 2 had evidence of dysfunction of Leydig cells as well. Primary hypogonadism was found in 1 female, who was heavily treated for relapse (ChT containing CYC, abdominal RT and craniospinal RT). She was amenorrhoic and needed substitutional estrogen therapy but delivered a child anyway. Five females had early puberty after cranial RT. One female had secondary hypogonadism and hyposomatotropism after cranial RT with 30 Gy, one male had hyposomatotropism after receiving cranial RT twice (49 Gy total). Primary treatment for leukemia does not produce primary hypogonadism in girls, but it does in boys. Alkylating agents and gonadal RT are the most damaging factors. Not only RT to gonads but also alkylating agents alone cause dysfunction of Leydig cells.