Cranial irradiation and growth hormone neurosecretory dysfunction: a critical appraisal

The Late Effects of Hematopoietic Stem Cell Transplants in Pediatric Patients: A 25-Year Review

CONTEXT

A rare, large, single-center study covering all long-term health outcomes of pediatric allogeneic hemopoietic stem cell transplant (HSCT) survivors, to provide comprehensive local data and identify gaps and future directions for improved care.

OBJECTIVE

To document endocrine sequelae and other late effects of all HSCT recipients.

DESIGN

Retrospective review.

SETTING

Royal Children's Hospital Melbourne.

PATIENTS

384 children and adolescents received HSCT; 228 formed the study cohort; 212 were alive at commencement of data accrual.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Incidence of endocrinopathies; fertility, growth, bone and metabolic status; subsequent malignant neoplasms (SMNs).

RESULTS

Gonadotoxicity was more common in females (P < .001). Total body irradiation (TBI) conditioning was more toxic than chemotherapy alone. All females receiving TBI or higher cyclophosphamide equivalent doses developed premature ovarian insufficiency. In males, impaired spermatogenesis +/- testicular endocrine dysfunction was associated with increasing testicular radiation exposure. Preservation of gonadal function was associated with younger age at HSCT. Of sexually active females, 22% reported spontaneous pregnancies. Short stature was common, with GH axis disruption in 30% of these. Of patients exposed to thyroid radiation, 51% developed nodules; 30% were malignant. Metabolic disturbances included hypertension and dyslipidemias, with both excess and underweight reported. Fragility fractures occurred in 6% and avascular necrosis in 6%. Thirteen percent developed SMNs, with the risk continuing to rise throughout follow-up.

CONCLUSION

We confirm gonadal dysfunction, multiple endocrine and metabolic abnormalities, thyroid cancer, and SMNs as common sequelae of HSCT and identify gaps in management-particularly the need for informed fertility counseling and pretreatment fertility preservation, evaluation, and management of bone health-and underline the need for early lifestyle modification, long-term surveillance, and prospective planned studies aimed at reducing complication risk.

Growth hormone after CNS tumor diagnosis: the fundamentals, fears, facts, and future directions

Growth hormone deficiency (GHD) may occur in pediatric patients with central nervous system (CNS) tumors at initial tumor presentation or later as treatment-related sequelae. While it is well recognized that growth hormone (GH) has beneficial effects on growth and endocrinopathies, there's often hesitancy by clinicians to initiate GH therapy for GHD after CNS tumor diagnosis due to the perceived increased risk of tumor recurrence. The available data is described here and based on this review, there is no evidence of increased risk of tumor recurrence or secondary malignancy in patients treated with GH after CNS tumor diagnosis. Further understanding of tumor biology and presence of downstream GH targets including insulin-like growth factor-1 (IGF-1) and insulin receptor activity is still needed.

Growth Hormone Deficiency and Treatment in Childhood Cancer Survivors

Growth hormone (GH) deficiency is a common pituitary hormone deficiency in childhood cancer survivors (CCS). The identification, diagnosis, and treatment of those individuals at risk are important in order to minimize associated morbidities that can be ameliorated by treatment with recombinant human GH therapy. However, GH and insulin-like growth factor-I have been implicated in tumorigenesis, so there has been concern over the use of GH therapy in patients with a history of malignancy. Reassuringly, GH therapy has not been shown to increase risk of tumor recurrence. These patients have an increased risk for development of meningiomas, but this may be related to their history of cranial irradiation rather than to GH therapy. In this review, we detail the CCS who are at risk for GHD and the existing evidence on the safety profile of GH therapy in this patient population.

Risk Factors for Small Adult Height in Childhood Cancer Survivors

PURPOSE

Between 10% and 20% of childhood cancer survivors (CCS) experience impaired growth, leading to small adult height (SAH). Our study aimed to quantify risk factors for SAH or growth hormone deficiency among CCS.

METHODS

The French CCS Study holds data on 7,670 cancer survivors treated before 2001. We analyzed self-administered questionnaire data from 2,965 CCS with clinical, chemo/radiotherapy data from medical records. SAH was defined as an adult height ≤ 2 standard deviation scores of control values obtained from a French population health study.

RESULTS

After exclusion of 189 CCS treated with growth hormone, 9.2% (254 of 2,776) had a SAH. Being young at the time of cancer treatment (relative risk [RR], 0.91 [95% CI, 0.88 to 0.95] by year of age), small height at diagnosis (≤ 2 standard deviation scores; RR, 6.74 [95% CI, 4.61 to 9.86]), pituitary irradiation (5-20 Gy: RR, 4.24 [95% CI, 1.98 to 9.06]; 20-40 Gy: RR, 10.16 [95% CI, 5.18 to 19.94]; and ≥ 40 Gy: RR, 19.48 [95% CI, 8.73 to 43.48]), having received busulfan (RR, 4.53 [95% CI, 2.10 to 9.77]), or > 300 mg/m² of lomustine (300-600 mg/m²: RR, 4.21 [95% CI, 1.61 to 11.01] and ≥ 600 mg/m²: RR, 9.12 [95% CI, 2.75 to 30.24]) were all independent risk factors for SAH. Irradiation of ≥ 7 vertebrae (≥ 15 Gy on ≥ 90% of their volume) without pituitary irradiation increased the RR of SAH by 4.62 (95% CI, 2.77 to 7.72). If patients had also received pituitary irradiation, this increased the RR by an additional factor of 1.3 to 2.4.

CONCLUSION

CCS are at a high risk of SAH. CCS treated with radiotherapy, busulfan, or lomustine should be closely monitored for growth, puberty onset, and potential pituitary deficiency.

Hypothalamic-Pituitary and Growth Disorders in Survivors of Childhood Cancer: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

To formulate clinical practice guidelines for the endocrine treatment of hypothalamic-pituitary and growth disorders in survivors of childhood cancer.

PARTICIPANTS

An Endocrine Society-appointed guideline writing committee of six medical experts and a methodologist.

CONCLUSIONS

Due to remarkable improvements in childhood cancer treatment and supportive care during the past several decades, 5-year survival rates for childhood cancer currently are >80%. However, by virtue of their disease and its treatments, childhood cancer survivors are at increased risk for a wide range of serious health conditions, including disorders of the endocrine system. Recent data indicate that 40% to 50% of survivors will develop an endocrine disorder during their lifetime. Risk factors for endocrine complications include both host (e.g., age, sex) and treatment factors (e.g., radiation). Radiation exposure to key endocrine organs (e.g., hypothalamus, pituitary, thyroid, and gonads) places cancer survivors at the highest risk of developing an endocrine abnormality over time; these endocrinopathies can develop decades following cancer treatment, underscoring the importance of lifelong surveillance. The following guideline addresses the diagnosis and treatment of hypothalamic-pituitary and growth disorders commonly encountered in childhood cancer survivors.

MANAGEMENT OF ENDOCRINE DISEASE: Neuroendocrine surveillance and management of neurosurgical patients

Advances in the management of traumatic brain injury, subarachnoid haemorrhage and intracranial tumours have led to improved survival rates and an increased focus on quality of life of survivors. Endocrine sequelae of the acute brain insult and subsequent neurosurgery, peri-operative fluid administration and/or cranial irradiation are now well described. Unrecognised acute hypopituitarism, particularly ACTH/cortisol deficiency and diabetes insipidus, can be life threatening. Although hypopituitarism may be transient, up to 30% of survivors of TBI have chronic hypopituitarism, which can diminish quality of life and hamper rehabilitation. Patients who survive SAH may also develop hypopituitarism, though it is less common than after TBI. The growth hormone axis is most frequently affected. There is also accumulating evidence that survivors of intracranial malignancy, who have required cranial irradiation, may develop hypopituitarism. The time course of the development of hormone deficits is varied, and predictors of pituitary dysfunction are unreliable. Furthermore, diagnosis of GH and ACTH deficiency require dynamic testing that can be resource intensive. Thus the surveillance and management of neuroendocrine dysfunction in neurosurgical patients poses significant logistic challenges to endocrine services. However, diagnosis and management of pituitary dysfunction can be rewarding. Appropriate hormone replacement can improve quality of life, prevent complications such as muscle atrophy, infection and osteoporosis and improve engagement with physiotherapy and rehabilitation.

GH deficiency in adult survivors of childhood cancer

Childhood cancer survivors (CCS) are a fast growing population, but late adverse effects of cancer therapies are not rare. In CCS treated with cranial radiotherapy, growth hormone deficiency (GHD) is a well-known occurrence and the potential impact of GH replacement therapy on the global outcome of CCS is under continuous evaluation. In the present review, we discuss advantages and disadvantages of GH replacement therapy in survivors of pediatric malignancies, taking into consideration the different reasons for treating GHD during childhood or adult life. It is doubtless that GH treatment is advisable to obtain a normal growth in pediatric patients. As far as the beginning/continuation of the replacement therapy in adult age is concerned, contrasting results have been reported in literature. The suggestion is that the decision to treat adult CCS should be taken after careful evaluation of each patient's clinical history and of the potential side effects, in agreement with the patients.

Long-term effects of treatment of pituitary adenomas

Pituitary adenomas can be treated effectively in the vast majority of cases. After successful treatment for pituitary disease, many patients still report reduced quality of life in the presence of persistent morbidity and (slightly) increased mortality. At present, there is an increasing awareness that in many cases long-term remission of functioning or nonfunctioning adenomas does not equal cure. The causes are most probably multifactorial. Hypopituitarism, intrinsic imperfections of surgical or endocrine replacement therapy, but also persistent effects of treatment and of previous hormone excess on the central nervous system all affect long-term morbidity, general well-being, and mortality. This implies that treatment goals for patients with pituitary adenomas will shift from long-term cure to long-term care. Further research is therefore needed to get more insight into each of these factors of influence, such as the extent of reversibility of hormone excess syndromes on cardiovascular risk and behavior. The fact that coping strategies, despite long-term remission, are altered and illness perceptions are affected strongly suggests that long-term care should incorporate self-management interventions that might help to improve quality of life for patients.

Growth hormone deficiency after childhood bone marrow transplantation with total body irradiation: interaction with adiposity and age

OBJECTIVE

Bone marrow transplantation with total body irradiation (BMT/TBI) has adverse effects on growth, growth hormone status and adiposity. We investigated the GH-IGF-I axis in relation to adiposity.

DESIGN

Cross-sectional case control study.

PATIENTS

BMT/TBI survivors (n = 22) and short stature control participants (n = 19), all GH-naïve or off GH treatment >3 months.

MEASUREMENTS

Auxology, DEXA scans and GH-IGF-I axis investigation: (i) 12-h overnight GH profiles; (ii) insulin tolerance test (ITT); and (iii) IGF-I generation test.

ANALYSIS

auto-deconvolution of GH profile data and comparison of quantitative parameters using ANOVA.

RESULTS

Eighty-two percent of BMT/TBI survivors had growth hormone deficiency (GHD) using ITT. GH profile area-under-the-curve (GH-AUC) was reduced in BMT/TBI survivors vs short stature control participants [geometric mean (range) 209 (21-825) vs 428 (64-1400) mcg/l/12 h, respectively, P = 0·007]. GHD was more marked in those who had additional cranial irradiation (CRT) [ITT peak 1·4 (0·2-3·0) vs TBI only 4·1 (1·1-14·8) mcg/l, P = 0·036]. GHD was more marked at the end of growth in BMT/TBI survivors vs short stature control participants (GH-AUC 551 (64-2474) vs 1369 (192-4197) mcg/l/12 h, respectively, P = 0·011) and more prevalent (9/11 vs 1/9, respectively, P = 0·005). GH profile data were consistent with ITT results in 80% of participants. IGF-I generation tests were normal. BMT/TBI survivors still demonstrated lower GH levels after adjustment for adiposity (fat-adjusted mean difference for GH-AUC 90·9 mcg/l/12 h, P = 0·025).

CONCLUSIONS

GHD was more prevalent in BMT/TBI survivors than expected for the CRT dose in TBI, worsened with time and persisted into adulthood. GHD could not be explained by adiposity. There was no evidence of GH neurosecretory dysfunction or resistance after BMT/TBI.

60 YEARS OF NEUROENDOCRINOLOGY: The hypothalamo-GH axis: the past 60 years

At the time of the publication of Geoffrey Harris's monograph on 'Neural control of the pituitary gland' 60 years ago, the pituitary was recognised to produce a growth factor, and extracts administered to children with hypopituitarism could accelerate growth. Since then our understanding of the neuroendocrinology of the GH axis has included identification of the key central components of the GH axis: GH-releasing hormone and somatostatin (SST) in the 1970s and 1980s and ghrelin in the 1990s. Characterisation of the physiological control of the axis was significantly advanced by frequent blood sampling studies in the 1980s and 1990s; the pulsatile pattern of GH secretion and the factors that influenced the frequency and amplitude of the pulses have been defined. Over the same time, spontaneously occurring and targeted mutations in the GH axis in rodents combined with the recognition of genetic causes of familial hypopituitarism demonstrated the key factors controlling pituitary development. As the understanding of the control of GH secretion advanced, developments of treatments for GH axis disorders have evolved. Administration of pituitary-derived human GH was followed by the introduction of recombinant human GH in the 1980s, and, more recently, by long-acting GH preparations. For GH excess disorders, dopamine agonists were used first followed by SST analogues, and in 2005 the GH receptor blocker pegvisomant was introduced. This review will cover the evolution of these discoveries and build a picture of our current understanding of the hypothalamo-GH axis.

Growth hormone exposure as a risk factor for the development of subsequent neoplasms of the central nervous system: a report from the childhood cancer survivor study

CONTEXT

Cranial radiation therapy (CRT) predisposes to GH deficiency and subsequent neoplasms (SNs) of the central nervous system (CNS). Increased rates of SNs have been reported in GH-treated survivors.

OBJECTIVE

The objective of the study was to evaluate the association between GH treatment and the development of CNS-SNs.

DESIGN

The study was designed with a retrospective cohort with longitudinal follow-up.

SETTING

The setting of the study was multiinstitutional.

PARTICIPANTS

A total of 12 098 5-year pediatric cancer survivors from the Childhood Cancer Survivor Study, diagnosed with cancer prior to age 21 years, of whom 338 self-reported GH treatment, which was verified through medical record review.

INTERVENTIONS

INTERVENTIONS included subject surveys, medical records abstraction, and pathological review.

OUTCOME MEASURES

Incidence of meningioma, glioma, and other CNS-SNs was measured.

RESULTS

Among GH-treated survivors, 16 (4.7%) developed CNS-SN, including 10 with meningioma and six with glioma. Two hundred three survivors without GH treatment (1.7%) developed CNS-SN, including 138 with meningioma, 49 with glioma, and 16 with other CNS-SNs. The adjusted rate ratio in GH-treated compared with untreated survivors for development of any CNS-SN was 1.0 [95% confidence interval (CI) 0.6-1.8, P = .94], for meningiomas, 0.8 (95% CI 0.4-1.7, P = .61), and for gliomas, 1.9 (95% CI 0.7-4.8, P = .21). Factors associated with meningioma development included female gender (P = .001), younger age at primary cancer diagnosis (P < .001), and CRT/longer time since CRT (P < .001). Glioma was associated with CRT/shorter time since CRT (P < .001).

CONCLUSIONS

There was no statistically significant increased overall risk of the occurrence of a CNS-SN associated with GH exposure. Specifically, occurrence of meningiomas and gliomas were not associated with GH treatment.

Alternative causes of hypopituitarism: traumatic brain injury, cranial irradiation, and infections

Hypopituitarism often remains unrecognized due to subtle clinical manifestations. Anterior pituitary hormone deficiencies may present as isolated or multiple and may be transient or permanent. Traumatic brain injury (TBI) is recognized as a risk factor for hypopituitarism, most frequently presenting with isolated growth hormone deficiency (GHD). Data analysis shows that about 15% of patients with TBI have some degree of hypopituitarism which if not recognized may be mistakenly ascribed to persistent neurologic injury and cognitive impairment. Identification of predictors for hypopituitarism after TBI is important, one of them being the severity of TBI. The mechanisms involve lesions in the hypothalamic-pituitary axis and inflammatory changes in the central nervous system (CNS). With time, hypopituitarism after TBI may progress or reverse. Cranial irradiation is another important risk factor for hypopituitarism. Deficiencies in anterior pituitary hormone secretion (partial or complete) occur following radiation damage to the hypothalamic-pituitary region, the severity and frequency of which correlate with the total radiation dose delivered to the region and the length of follow-up. These radiation-induced hormone deficiencies are irreversible and progressive. Despite numerous case reports, the incidence of hypothalamic-pituitary dysfunction following infectious diseases of the CNS has been underestimated. Hypopituitarism usually relates to the severity of the disease, type of causative agent (bacterial, TBC, fungal, or viral) and primary localization of the infection. Unrecognized hypopituitarism may be misdiagnosed as postencephalitic syndrome, while the presence of a sellar mass with suprasellar extension may be misdiagnosed as pituitary macroadenoma in a patient with pituitary abscess which is potentially a life-threatening disease.

Radiation-induced hypopituitarism

PURPOSE OF REVIEW

Progressive and irreversible neuro-endocrine dysfunction following radiation-induced damage to the hypothalamic-pituitary (h-p) axis is the most common complication in cancer survivors with a history of cranial radiotherapy involving the h-p axis and in patients with a history of conventional or stereotactic pituitary radiotherapy for pituitary tumours. This review examines the controversy about the site and pathophysiology of radiation damage while providing an epidemiological perspective on the frequency and pattern of radiation-induced hypopituitarism.

RECENT FINDINGS

Contrary to the previously held belief that h-p axis irradiation with doses less than 40 Gy result in a predominant hypothalamic damage with time-dependent secondary pituitary atrophy, recent evidence in survivors of nonpituitary brain tumours suggests that cranial radiation causes direct pituitary damage with compensatory increase in hypothalamic release activity. Sparing the hypothalamus from significant irradiation with sterteotactic radiotherapy for pituitary tumours does not appear to reduce the long-term risk of hypopituitarism.

SUMMARY

Radiation-induced h-p dysfunction may occur in up to 80% of patients followed long term and is often associated with an adverse impact on growth, body image, skeletal health, fertility, sexual function and physical and psychological health. A detailed understanding of pathophysiological and epidemiological aspects of radiation-induced h-p axis dysfunction is important to provide targeted and reliable long-term surveillance to those at risk so that timely diagnosis and hormone-replacement therapy can be provided.

Radiotherapy-induced hypopituitarism: a review

Hypopituitarism is a disorder caused by impaired hormonal secretions from the hypothalamic-pituitary axis. Radiotherapy is the most common cause of iatrogenic hypopituitarism. The hypothalamic-pituitary axis inadvertently gets irradiated in patients receiving prophylactic cranial radiotherapy for leukemia, total body irradiation and radiotherapy for intracranial, base skull, sinonasal and nasopharyngeal tumors. Radiation-induced hypopituitarism (RIH) is insidious, progressive and largely nonreversible. Mostly, RIH involves one hypothalamic-pituitary axis; however, multiple hormonal axes deficiency starts developing at higher doses. Although the clinical effects of the hypopituitarism are more profound in children and young adults, its implications in older adults are being increasingly recognized. The risk continues to persist or increase up to 10 years following radiation exposure. The clinical management of hypopituitarism is challenging both for the patients and healthcare providers. Here we have reviewed the scale of the problem, the risk factors and the management of RIH.

Pilot study on sex hormone levels and fertility in women with malignant gliomas

The standard treatment of patients with high-grade gliomas based on conformal radiation therapy (RT) with or without chemotherapy (CT) may induce endocrine deficiencies of pituitary and subsequently also of peripheral hormones. In 24 premenopausal women with high-grade gliomas treated with RT and CT, hormonal changes and their impact on quality of life were investigated. Serum concentrations of gonadal, pituitary and of thyroid hormones were measured at various time points after initial anti-neoplastic therapy. Additionally, endovaginal ultrasound was performed and patients' quality of life (QLQ) and female role functioning were assessed. Of 24 patients, 23 (96%) reported a change in their menstrual pattern. Twenty-one patients reported at least transient amenorrhoea with a mean duration of 26.1 months (3-96 months). Increased prolactin serum levels were found in 10 women, 8 of them with amenorrhoea. Thirteen women showed menopausal or perimenopausal hormone pattern, 3 a pattern compatible with hypogonadism. Changes in thyroid hormone levels were seen in 8 patients. Furthermore, patients complained about fatigue and menopausal symptoms, like flushes, weakness and gain of weight. They felt a decrease of libido combined with the loss of attractiveness as a female, and an increased need for tender care and security. The hormonal deficiencies in female patients with malignant gliomas require thorough evaluation and individualized diagnosis and sometimes intervention.

Postradiation therapy hypopituitarism

The increasing use of radiation treatment for head and neck cancers and other tumors, including pituitary adenomas, from the mid-20th Century onwards led to the recognition that pituitary function may be affected - often leading to some degree of pituitary insufficiency. Our knowledge is mostly based on observational or retrospective rather than randomized prospective studies. The various axes may be impacted at the hypothalamic or pituitary levels, or both. Some axes - the somatotropic and gonadotropic - appear to be especially vulnerable to radiation damage and may be affected quite early, whereas posterior pituitary function is rarely affected. Increased use of stereotactic radiosurgery, which focuses the radiation dose on the abnormal tissue, may be expected to reduce the impact on normal pituitary function, but such studies that are available are, as yet, relatively short term. Prospective studies of the effect of stereotactic radiosurgery on pituitary function would be valuable.

Intracranial metastatic disease rarely involves the pituitary: retrospective analysis of 935 metastases in 155 patients and review of the literature

We present a case report of a patient recently treated at our institution for an isolated non-small cell lung cancer metastatic lesion to the sella, report the lack of involvement of the pituitary gland in a large single-institution series of treated intracranial parenchymal metastases, and review the pertinent literature. We reviewed cranial imaging studies (CT and MRI) for 935 metastases in 155 patients treated at our institution over the previous 3 years for intracranial metastatic disease. Special attention was paid to the skull base to document the presence of any metastatic disease involving the pituitary gland, infundibular stalk, sella turcica (including anterior and posterior clinoids), or diaphragm sellae. We found no other involvement of the pituitary gland or other sellar structures by metastatic disease in this series. Intracranial metastatic disease rarely involves the pituitary gland and infundibular stalk parenchyma, suggesting that this structure may be safely omitted from the treatment field during WBRT and prophylactic cranial irradiation (PCI). This treatment approach should reduce the late sequelae of treatment to this critical organ.

Hypopituitarism following traumatic brain injury: prevalence is affected by the use of different dynamic tests and different normal values

OBJECTIVE

Traumatic brain injury (TBI) has emerged as an important cause of hypopituitarism. However, considerable variations in the prevalence of hypopituitarism are reported. These can partly be explained by severity of trauma and timing of hormonal evaluation, but may also be dependent on endocrine tests and criteria used for diagnosis of hypopituitarism.

METHODS

Systematic review of studies reporting prevalence of hypopituitarism in adults >or=1 year after TBI focusing on used (dynamic) tests and biochemical criteria.

RESULTS

We included data from 14 studies with a total of 931 patients. There was considerable variation in definition of hypopituitarism. Overall, reported prevalences of severe GH deficiency varied between 2 and 39%. Prevalences were 8-20% using the GHRH-arginine test (cutoff <9 microg/l), 11-39% using the glucagon test (cutoff 1-5 microg/l), 2% using the GHRH test (no cutoff), and 15-18% using the insulin tolerance test (ITT; cutoff <3 microg/l). Overall, the reported prevalence of secondary adrenal insufficiency had a broad range from 0 to 60%. This prevalence was 0-60% with basal cortisol (cutoff <220 or <440 nmol/l), 7-19% using the ACTH test, and 5% with the ITT as first test (cutoff <500 or <550 nmol/l). Secondary hypothyroidism was present in 0-19% (free thyroxine) or 5-15% (thyroid-releasing hormone stimulation). Secondary hypogonadism was present in 0-29%.

CONCLUSION

The reported variations in the prevalence rates of hypopituitarism after TBI are in part caused by differences in definitions, endocrine assessments of hypopituitarism, and confounding factors. These methodological issues prohibit simple generalizations of results of original studies on TBI-associated hypopituitarism in the perspective of meta-analyses or reviews.

[Evaluating diagnosis methods on childhood GH (DGH) deficiency: IGFs, IGFBPs, releasing tests, GH rhythm and image exams]

The diagnostic approach to growth hormone deficiency (GHD) in children with short stature (SS) is controversial. Here we review the available methodology and present prospective data obtained in a cohort of patients with SS suggesting the use of screening test followed by the confirmation test. Thus, the children with SS should be submitted to clinical and laboratorial evaluation to exclude of chronic and genetic diseases. In addition patients with height<3 percentile or growth velocity<percentile 25, IGF-1 levels should be measured. If the IGF1 levels<-1 standard deviation (SD) compared to the age, GHD should be confirmed by two GH-stimulations tests (peak<5 mcg/L). In risk factor patients, IGF-1<-1 SD and one non-responsible GH-test, the GHD was confirmed. Children with IGF-1>-1 SD, the growth velocity should have observed and GH/IGF-1 axis re-evaluated if the growth pattern is not satisfactory.

Growth hormone deficiency is associated with decreased quality of life in patients with prior acromegaly

CONTEXT

Both GH deficiency (GHD) and GH excess are associated with a decreased quality of life. However, it is unknown whether patients with GHD after treatment for acromegaly have a poorer quality of life than those with normal GH levels after cure of acromegaly.

OBJECTIVE

The aim of the study was to determine whether patients with GHD and prior acromegaly have a poorer quality of life than those with GH sufficiency after cure of acromegaly.

DESIGN AND SETTING

We conducted a cross-sectional study in a General Clinical Research Center.

STUDY PARTICIPANTS

Forty-five patients with prior acromegaly participated: 26 with GHD and 19 with GH sufficiency.

INTERVENTION

There were no interventions.

MAIN OUTCOME MEASURES

We evaluated quality of life, as measured by 1) the Quality of Life Adult Growth Hormone Deficiency Assessment (QoL-AGHDA); 2) the Short-Form Health Survey (SF-36); and 3) the Symptom Questionnaire.

RESULTS

Mean scores on all subscales of all questionnaires, except for the anger/hostility and anxiety subscales of the Symptom Questionnaire, showed significantly impaired quality of life in the GH-deficient group compared with the GH-sufficient group. Peak GH levels after GHRH-arginine stimulation levels were inversely associated with QoL-AGHDA scale scores (R = -0.53; P = 0.0005) and the Symptom Questionnaire Depression subscale scores (R = -0.35; P = 0.031) and positively associated with most SF-36 subscale scores.

CONCLUSIONS

Our data are the first to demonstrate a reduced quality of life in patients who develop GHD after cure of acromegaly compared to those who are GH sufficient. Further studies are warranted to determine whether GH replacement would improve quality of life for patients with GHD after cure from acromegaly.

Cranially irradiated adult cancer survivors may have normal spontaneous GH secretion in the presence of discordant peak GH responses to stimulation tests (compensated GH deficiency)

CONTEXT

We have previously demonstrated that spontaneous (physiological) GH secretion was entirely normal in cranially irradiated patients who had normal individual peak GH responses to the insulin tolerance test (ITT) but reduced maximal somatotroph reserve as indicated by substantially reduced group GH responses to the GHRH + arginine stimulation test (AST). The normality of spontaneous GH secretion was attributed to a compensatory increase in hypothalamic stimulatory input within a partially damaged hypothalamic-pituitary (h-p) axis. It is unknown, however, if such compensatory stimulation can also maintain normality of GH secretion in those who fail the ITT but pass the GHRH + AST. STUDY SUBJECTS AND DESIGN: We studied 24-h spontaneous GH secretion by 20-min sampling both in the fed state (n = 11) and in the last 24 h of a 33-h fast (n = 9) in adult cancer survivors with subnormal peak GH responses to the ITT but either normal or relatively less attenuated peak GH responses to the GHRH + AST. The study was conducted 8.3 +/- 1.8 (range 2-23) years after cranial irradiation for nonpituitary brain tumours (n = 9) or leukaemia/lymphoma (n = 2) in comparison with 30 normal controls (fasting, 14).

RESULTS

Previously published diagnostic thresholds for the ITT, GHRH + AST and spontaneous GH secretion were used to characterize GH secretion. Four of the 11 patients with impaired stimulated responses to both tests showed only minor discordancies between stimulated and spontaneous GH secretion. Two of the remaining seven patients had subnormal spontaneous GH secretion. However, spontaneous GH secretion, both individually and as a group, was entirely normal in the remaining five patients who had impaired GH responses to the ITT but normal individual responses to the GHRH + AST; in these five patients, IGF-I standard deviation scores (SDS; -2.7 to -0.8) were significantly reduced to a moderate degree compared with normals.

CONCLUSIONS

In cranially irradiated adult cancer survivors, it cannot be assumed that failure to pass the ITT in isolation reflects severe GH deficiency (GHD). It appears that in some patients near-maximal compensatory overdrive of the partially damaged somatotroph axis may result in near-normal quantitative restoration of spontaneous GH secretion, thus limiting further stimulation with the ITT to the extent that impaired GH responses can be seen even before spontaneous GH secretion starts to decline in adults. However, IGF-I status continues to provide useful information about the adequacy of the compensatory process and therefore the degree of normality of GH secretion.

Hypopituitarism following radiotherapy

Deficiencies in anterior pituitary hormones secretion ranging from subtle to complete occur following radiation damage to the hypothalamic-pituitary (h-p) axis, the severity and frequency of which correlate with the total radiation dose delivered to the h-p axis and the length of follow up. Selective radiosensitivity of the neuroendocrine axes, with the GH axis being the most vulnerable, accounts for the high frequency of GH deficiency, which usually occurs in isolation following irradiation of the h-p axis with doses less than 30 Gy. With higher radiation doses (30-50 Gy), however, the frequency of GH insufficiency substantially increases and can be as high as 50-100%. Compensatory hyperstimulation of a partially damaged h-p axis may restore normality of spontaneous GH secretion in the context of reduced but normal stimulated responses; at its extreme, endogenous hyperstimulation may limit further stimulation by insulin-induced hypoglycaemia resulting in subnormal GH responses despite normality of spontaneous GH secretion in adults. In children, failure of the hyperstimulated partially damaged h-p axis to meet the increased demands for GH during growth and puberty may explain what has previously been described as radiation-induced GH neurosecretory dysfunction and, unlike in adults, the ITT remains the gold standard for assessing h-p functional reserve. Thyroid-stimulating hormone (TSH) and ACTH deficiency occur after intensive irradiation only (>50 Gy) with a long-term cumulative frequency of 3-6%. Abnormalities in gonadotrophin secretion are dose-dependent; precocious puberty can occur after radiation dose less than 30 Gy in girls only, and in both sexes equally with a radiation dose of 30-50 Gy. Gonadotrophin deficiency occurs infrequently and is usually a long-term complication following a minimum radiation dose of 30 Gy. Hyperprolactinemia, due to hypothalamic damage leading to reduced dopamine release, has been described in both sexes and all ages but is mostly seen in young women after intensive irradiation and is usually subclinical. A much higher incidence of gonadotrophin, ACTH and TSH deficiencies (30-60% after 10 years) occur after more intensive irradiation (>60 Gy) used for nasopharyngeal carcinomas and tumors of the skull base, and following conventional irradiation (30-50 Gy) for pituitary tumors. The frequency of hypopituitarism following stereotactic radiotherapy for pituitary tumors is mostly seen after long-term follow up and is similar to that following conventional irradiation. Radiation-induced anterior pituitary hormone deficiencies are irreversible and progressive. Regular testing is mandatory to ensure timely diagnosis and early hormone replacement therapy.

Pituitary hypoplasia and growth hormone deficiency in a woman with glycogen storage disease type Ia: a case report

INTRODUCTION

Growth retardation is one of the cardinal manifestations of glycogen storage disease type Ia. It is unclear which component of the growth hormone and/or insulin-like growth factor axis is primarily disrupted, and management of growth impairment in these patients remains controversial. Here we report the first case in the literature where glycogen storage disease type Ia is associated with pituitary hypoplasia and growth hormone deficiency.

CASE PRESENTATION

A 20-year-old woman with glycogen storage disease type Ia was admitted to our endocrinology department because of growth retardation. Basal and overnight growth hormone sampling at 2-hour intervals demonstrated low levels; however, provocative testing revealed a relatively normal growth hormone response. A hypoplastic anterior pituitary with preserved growth hormone response to provocative testing suggested the possibility of growth hormone neurosecretory dysfunction and/or primary pituitary involvement.

CONCLUSION

Pituitary hypoplasia may result from growth hormone-releasing hormone deficiency, a condition generally known as growth hormone neurosecretory dysfunction. It is an abnormality with a spontaneous and pulsatile secretion pattern, characterized by short stature, growth retardation and normal serum growth hormone response to provocative testing. However, in the case described in this report, a normal although relatively low growth hormone response during insulin tolerance testing and pituitary hypoplasia suggested that primary pituitary involvement or growth hormone neurosecretory dysfunction may occur in glycogen storage disease type Ia. This is a potential cause of growth failure associated with a lower somatotroph mass, and may explain the variable responsiveness to growth hormone replacement therapy in people with glycogen storage disease.