Hypopituitarism.

Hypopituitarism refers to deficiency of one or more hormones produced by the anterior pituitary or released from the posterior pituitary. Hypopituitarism is associated with excess mortality, a key risk factor being cortisol deficiency due to adrenocorticotropic hormone (ACTH) deficiency. Onset can be acute or insidious, and the most common cause in adulthood is a pituitary adenoma, or treatment with pituitary surgery or radiotherapy. Hypopituitarism is diagnosed based on baseline blood sampling for thyroid stimulating hormone, gonadotropin, and prolactin deficiencies, whereas for ACTH, growth hormone, and antidiuretic hormone deficiency dynamic stimulation tests are usually needed. Repeated pituitary function assessment at regular intervals is needed for diagnosis of the predictable but slowly evolving forms of hypopituitarism. Replacement treatment exists in the form of thyroxine, hydrocortisone, sex steroids, growth hormone, and desmopressin. If onset is acute, cortisol deficiency should be replaced first. Modifications in replacement treatment are needed during the transition from paediatric to adult endocrine care, and during pregnancy.

Hypothyroidism following childhood cancer therapy-an under diagnosed complication.

To determine the prevalence of hypothyroidism amongst most adult survivors of childhood cancer in Britain using the British Childhood Cancer Survivor Study (BCCSS). The BCCSS is a population based cohort of individuals diagnosed with childhood cancer between 1940 and 1991 and who survived at least 5 years from diagnosis (n = 17,981). 10483, 71% of those survivors aged at least 16 years, returned a completed questionnaire, which asked if hypothyroidism had been diagnosed. Of the whole cohort, 7.7% reported hypothyroidism with the highest risk among patients treated for Hodgkin's disease (HD) (19.9%), CNS neoplasms (15.3%), Non-Hodgkin's lymphoma (6.2%) and leukaemia (5.2%). Survivors were more likely to develop hypothyroidism if they had received radiotherapy for HD (p = 0.0001) or a CNS neoplasm (p < 0.00005) but not leukaemia (p = 0.3). In these three patient groups, the frequency of hypothyroidism was similar in men and women. Survivors of irradiated CNS tumours reported a prevalence of hypothyroidism, which was substantially lower if discharged to primary care compared with being on hospital follow-up and which declined substantially with increased follow-up in both primary care (p = 0.004) and hospital follow-up (p = 0.023) settings. Hypothyroidism is a common finding amongst adult survivors of childhood malignancy. The substantial differences in reported hypothyroidism prevalence after irradiated CNS neoplasms suggests substantial under-diagnosis, which increased with increased follow-up, and which increased among those followed-up in primary care compared with hospital settings.

Serum vascular endothelial growth factor (VEGF) is elevated in GH deficient adults.

OBJECTIVE: GHD adults exhibit a number of adverse surrogate markers of vascular risk culminating in excess vascular morbidity and mortality. Vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of a number of vascular morbidities. Furthermore, serum levels decrease following GH replacement in GHD adults, though it remains unclear if levels are significantly elevated in untreated individuals. DESIGN: A cross-sectional case-control study. METHODS: We measured fasting serum VEGF, MMP2, and MMP9 in 27 patients with GHD, 24 with partial GHD (GHI), and 25 sex- and age-matched controls. RESULTS: GHD (483±334 vs 326±180ng/l, P=0.04), but not GHI (354±192 vs 326±180ng/l, P=n/s) adults had significantly elevated VEGF levels compared with controls. Neither MMP2, nor MMP9 levels were elevated in the patient groups. Serum VEGF levels correlated positively with LDL-cholesterol (R=0.34, P=0.004) and serum MMP9 values (R=0.36, P=0.002), and negatively with IGF-I values, however, no correlation was observed with MMP2. Multiple regression analysis with VEGF levels as the dependent variable, and age, gender, % fat mass, LDL-C, insulin and IGF-I as independent variables revealed VEGF levels to be dependent on LDL-C alone (P=0.003, R=0.36). CONCLUSION: GHD adults have elevated VEGF levels, which correlate with MMP9 levels. Both VEGF and MMP9 are associated with vascular pathologies and may provide insight in to the pathophysiological mechanisms underlying the increased vascular morbidity and mortality observed in GHD adults.

Partial growth hormone deficiency in adults; should we be looking for it?

Quantitatively, GH secretion exists as a continuum in states ranging from good health through to hypopituitarism. Currently, GH replacement is considered only for adults designated as being severely GH deficient (GHD). In clinical practice the gold standard, on which the biochemical diagnosis of severe GHD is based, centres on the presence of two or more additional anterior pituitary hormone deficits. Cohorts of adults with partial GHD (Growth Hormone Insufficiency [GHI]) have been reported with adverse body composition changes, dyslipidaemia, insulin resistance, altered cardiac performance and increased carotid intima-media thickness. The diagnosis of GHI in an individual patient, however, is extremely difficult because such patients rarely exhibit additional anterior pituitary hormone deficits, and the levels of GH-dependent proteins, including IGF-I, are normal in the majority. Currently, GH replacement therapy should only be considered in a patient characterized as GHI by dynamic GH testing in whom there is a plausible cause for hypopituitarism and in whom the IGF-I level is pathologically low.

Quality of life, self-esteem, fatigue, and sexual function in young men after cancer: a controlled cross-sectional study.

BACKGROUND: Androgen deficiency is increasingly recognized in young male cancer survivors; however, its impact on quality of life (QOL) is not established. The authors investigated the relationship between androgen levels, QOL, self-esteem, fatigue, and sexual function in young male cancer survivors compared with control subjects. METHODS: A cross-sectional, observational study of 176 male cancer survivors and 213 male controls aged 25 to 45 years was performed. Subjects completed 3 QOL scales (Medical Outcomes Study 36-Item Short-Form Health Survey version 2, the 12-item General Health Questionnaire [GHQ-12], and Aging Male Scale), and measures of self-esteem (Rosenberg Self-Esteem Scale), fatigue (Functional Assessment of Chronic Illness Therapy-Fatigue), and sexual function (Derogatis Interview for Sexual Functioning-II Self-Report-Male). RESULTS: Cancer survivors had lower scores for all components of the Short-Form Health Survey, Aging Male Scale, and Functional Assessment of Chronic Illness Therapy-Fatigue, and for 4 of 5 subsections of the Derogatis Interview for Sexual Functioning than controls. The majority of these differences remained after adjusting by linear regression analysis. Levels of psychiatric disorder or self-esteem did not differ between the 2 groups. In cancer survivors, those with androgen deficiency (serum testosterone < or = 10 nmol/L) had lower scores than those without for all components of the Short-Form Health Survey, the General Health Questionnaire, Functional Assessment of Chronic Illness Therapy-Fatigue, and the Derogatis Interview for Sexual Functioning. Serum testosterone only weakly correlated with health measures. CONCLUSIONS: Young male cancer survivors self-report a marked impairment in QOL, energy levels, and quality of sexual functioning, and this was exacerbated in those with androgen deficiency. However, psychological distress was not elevated, self-esteem was normal, and sexual relationships were not impaired. The relationship with testosterone is complex, and appears dependent on a threshold level rather than direct correlation. Interventional trials are needed to determine whether testosterone replacement would improve QOL in young male cancer survivors.

Partial growth hormone deficiency is associated with an adverse cardiovascular risk profile and increased carotid intima-medial thickness.

OBJECTIVE: To quantify the relative prevalence of surrogate markers of vascular risk in adults with partial GH deficiency (GH insufficiency, GHI). CONTEXT: Hypopituitary adults with untreated GH deficiency (GHD) have an excess vascular mortality and demonstrate clustering of adverse vascular risk factors. The vascular risk profile of GHI adults has yet to be comprehensively studied. DESIGN: A cross-sectional case controlled study. PATIENTS: Thirty GHD adults, 24 GHI, and 30 age- and sex-matched controls. GHI adults were defined biochemically using two GH stimulation tests (peak GH 3-7 µg/l). MEASUREMENTS: Serum lipids and apolipoproteins, plasminogen activator inhibitor type-I (PAI-I), C-reactive protein (CRP), lipoprotein (a) [Lp(a)], fibrinogen, blood pressure and carotid intima-medial thickness (IMT). RESULTS: IGF-I levels of GHI adults were lower than controls (373 ± 123 vs 295 ± 104 µg/l; P < 0.001). Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) values were consistently between those of, but not significantly different from, GHD and control subjects. GHI adults showed significantly elevated PAI-I levels [80 (13-98) vs 50.5 (3-98) ng/ml; P = 0.01], although no there were differences in CRP, Lp(a), and fibrinogen levels compared with control subjects. No differences in systolic or diastolic blood pressure were shown between study groups. In parallel with the increased vascular risk profile of GH-insufficient adults, carotid IMT was significantly increased (0.503 ± 0.08 vs 0.578 ± 0.130 mm; P = 0.02). TC, LDL-C, Waist-Hip Ratio (WHR), truncal fat mass, and IMT correlated with IGF-I levels and GH status. TG, K(ITT), and PAI-I additionally correlated with GH status, but not with IGF-I levels. CONCLUSION: GHI adults are at elevated vascular risk, reflected by adverse surrogate markers and increased carotid IMT. The surrogate risk marker profile parallels GHD adults, but is less divergent from that observed in healthy individuals. No data are yet available as to whether these anomalies will be reflected in an increased vascular mortality in GHI adults.

Assessment of quality of life in adult patients with GH deficiency: KIMS contribution to clinical practice and pharmacoeconomic evaluations.

Quality of life (QoL) has emerged as an important construct that has found numerous applications across healthcare-related fields, ranging from research and clinical evaluation of treatment effects to pharmacoeconomic evaluations and global healthcare policy. Impairment of QoL is one of the key clinical characteristics in adult GHD and has been extensively studied in the Pfizer International Metabolic Database (KIMS). We provide summarized evidence on GH treatment effects for both clinical and health economic applications based on the KIMS data. The primary focus is on those aspects of QoL research that cannot be investigated in the traditional clinical trial setting, such as specific patient subgroups, cross-country comparisons and long-term follow-up. First, the impact of age, gender, disease onset, primary aetiology, extent of hypopituitarism, previous radiotherapy and obesity on QoL before and during long-term GH replacement is discussed. Secondly, the studies on QoL in relation to country-specific normative values are reviewed. Finally, health economic data derived from KIMS including both burden of disease and utility assessment are evaluated. We conclude that the wide spectrum of analyses performed on the KIMS data allows for practical application of the results not only to research and clinical practice but also to health policy and global medical decision making.

Normal testicular function and spermatogenesis.

The testis performs two basic functions, sperm production and testosterone secretion. Formation of the testis is genetically controlled; expression of the SRY gene directs the embryonic gonads into the pathway leading to the development of testes. By the fourth week of gestation in humans, the primordial germ cells derived from pluripotent cells of the embryonic epiblast proliferate and migrate from the endoderm of the yolk sac into the undifferentiated gonad, which becomes morphologically distinct during the seventh week of gestation in humans. Histological development of the testis is largely completed by the end of the third month of gestation.

Hypopituitarism following Radiotherapy Revisited.

Neuroendocrine disturbances in anterior pituitary hormone secretion are common 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. The somatotropic axis is the most vulnerable to radiation damage and GH deficiency remains the most frequently seen endocrinopathy. Compensatory hyperstimulation of a partially damaged somatotropic axis may restore normality of spontaneous GH secretion in the context of reduced but normal stimulated responses in adults. At its extreme, endogenous hyperstimulation may limit further stimulation by insulin-induced hypoglycaemia resulting in subnormal GH responses despite the normality of spontaneous GH secretion. In children, failure of the hyper-stimulated 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 insulin tolerance test remains the gold standard for assessing H-P functional reserve. With low radiation doses (<30 Gy) GH deficiency usually occurs in isolation in about 30% of patients, while with radiation doses of 30-50 Gy, the incidence of GH deficiency can reach 50-100% and long-term gonadotropin, TSH and ACTH deficiencies occur in 20-30, 3-9 and 3-6% of patients, respectively. With higher dose cranial irradiation (>60 Gy) or following conventional irradiation for pituitary tumours (30-50 Gy), multiple hormonal deficiencies occur in 30-60% after 10 years of follow-up. Precocious puberty can occur after radiation doses of <30 Gy in girls only, and in both sexes equally with a radiation dose of 30-50 Gy. Hyperprolactinaemia, due to hypothalamic damage is mostly seen in young women after high dose cranial irradiation and is usually subclinical. H-P dysfunction is progressive and irreversible and can have an adverse impact on growth, body image, sexual function and quality of life. Regular testing is advised to ensure timely diagnosis and early hormone replacement therapy.

The use of thyroid function tests in the diagnosis of hypopituitarism: definition and evaluation of the TSH Index.

BACKGROUND: TSH secretion in hypopituitary patients may be decreased due to TSH deficiency but it also remains under feedback inhibition by free thyroxine (fT4). We propose a TSH index (TSHI), as 'fT4-adjusted TSH', that corrects for any physiological TSH suppression, to provide a true estimate of pituitary thyrotroph function and any pathological pituitary suppression. METHODS: A total of 9519 thyroid function tests (TFTs) (Bayer Immuno-1) in 4064 patients of our institution were examined, including 444 patients investigated for hypopituitarism. Based on the physiological log-linear relationship between fT4 and TSH, we estimated the amount of feedback-induced change in log TSH per change in fT4, which allowed the extrapolation of log TSH to a fixed fT4 of 0, defining the TSHI. TSHIs were compared with other measures of pituitary function. RESULTS: Feedback inhibition was estimated to cause a 0.1345 decrease in log TSH (mU/l) for 1 pmol/l increase in fT4 concentration, therefore TSHI = log TSH + 0.1345 x fT4. Patients with lower peak-stimulated GH and cortisol concentrations had a significantly lower TSHI (P < 0.0001). TSHIs measured before pituitary stimulation tests predicted highly significantly the risk of test failure (P = 0.0002). Of all potential fT4-TSH combinations within the current reference ranges, 21.9% were identified as abnormal on the basis of the TSHI. CONCLUSION: The TSHI provides an accurate estimate of the severity of pituitary dysfunction in hypopituitary patients based on simple TFTs. It predicts the probability of pituitary stimulation test failure and extends the diagnosis of TSH deficiency into areas of the normal TFT reference ranges.

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.

Effect of aromatizable and unaromatizable androgen replacement in hypogonadal men on GH responsiveness.

OBJECTIVES: Although studies have clearly demonstrated that oestrogen replacement affects GH responsiveness by causing relative GH resistance, the effect of androgen replacement is unknown. Circumstantial evidence only suggests that androgen replacement may increase GH sensitivity and/or responsiveness. To examine the impact of androgens on GH responsiveness, hypogonadal men underwent the IGF-1 generation test in the unreplaced state, replaced with testosterone (T) and also replaced with dihydrotestosterone (DHT), its nonaromatizable metabolite. DESIGN AND PATIENTS: Twelve hypogonadal men with a normal GH axis were recruited. Each subject in random order had 4 weeks off T (NoRx), 4 weeks on T gel (TG) and 4 weeks on DHT gel (DHTG) applied daily, with 1 week washout between each preparation. An IGF-1 generation test using a subcutaneous injection of 7 mg of GH was performed at the end of each of these 4-week phases. MEASUREMENTS: Serum GHBP, total and free IGF-1, IGFBP-3 and acid-labile subunit (ALS) levels were measured at baseline and 24 h (peak) after GH administration. RESULTS: Despite a decrease in GHBP during the TG and DHTG phases, there were no observed differences in baseline, peak or increment (peak - baseline) total or free IGF-1 between the NoRx, TG or DHTG phases. CONCLUSIONS: There is no evidence of fluctuation in GH responsiveness in hypogonadal men, untreated or replaced with T or DHT alone. This implies that the increased level of oestradiol as a consequence of T replacement in hypogonadal men does not impact significantly on GH responsiveness, nor is there evidence of an androgen effect with elevated DHT levels as a consequence of either T or DHT replacement.

GH sensitivity of GH-deficient adults is dependent on gender but not timing of onset.

BACKGROUND: Females secrete 2-3 -fold greater amounts of GH compared with males despite maintaining similar IGF-I levels. IGF-I generation tests in healthy subjects suggest this discordancy results from relative resistance to GH in females. In GHD females the presumed relative insensitivity to GH is reflected by a lower basal IGF-I and the need for higher GH maintenance doses during replacement. Adults with severe GHD of childhood-onset (CO) have lower basal IGF-I SDS and require higher GH maintenance doses compared with adult-onset (AO) patients with GHD of equal severity. We hypothesised CO-GHD adults to be less sensitive to GH than AO-GHD patients. METHODOLOGY: In a single site study we analysed the incremental change in IGF-I (DeltaIGF-I) in 116 GHD adults following initiation of GH replacement. The data were corrected to provide DeltaIGF-I/mg GH because of slight variances in initial GH dose. RESULTS: Following GH replacement DeltaIGF-I was 230 +/- 245 and 356 +/- 278 ng/ml/mg GH in females and males, respectively (P = 0.01). In CO and AO patients DeltaIGF-I was 282 +/- 206 and 294 +/- 292 ng/ml/mg GH, respectively (P = 0.83). Further analysis after stratification by both gender and timing of onset of GHD showed DeltaIGF-I was 226 +/- 164, 324 +/- 228, 231 +/- 268, and 373 +/- 304 ng/ml/mg GH in the CO females, CO males, AO females, and AO males, respectively (AO males vs. AO females, P = 0.03; CO males vs. CO females, P = 0.17; AO males vs. CO males, P > 0.05; AO females vs. CO females, P > 0.05). Multiple linear regression with DeltaIGF-I as the dependent variable and age, gender, BMI, baseline IGF-I level, and timing of onset as independent variables showed DeltaIGF-I to be dependent on gender alone (R = 0.28, P = 0.004). Age (P = 0.44), BMI (P = 0.54), baseline IGF-I level (P = 0.63) and timing of onset (P = 0.61) had no effect on DeltaIGF-I. CONCLUSION: We have shown gender to have a significant impact on GH sensitivity in GHD adults, which, at least in part, explains differences in maintenance dosages during replacement. None of the additional variables impacted significantly on GH sensitivity. The lower basal IGF-I SDS and higher GH replacement requirement reported in CO compared with AO patients cannot be explained by differences in sensitivity to GH.

Do doctors discuss fertility issues before they treat young patients with cancer?

BACKGROUND: Many children treated for cancer are at risk of infertility, but for girls and prepubertal boys, all fertility preservation techniques remain experimental. We have assessed UK practice relating to information provision about the effects of cancer treatment on fertility and options for fertility preservation. METHODS: Paediatric oncologists prospectively completed a data form for each new patient registered over a 12 month period. RESULTS: Data were available on 1030 patients (68% of total registered). The effect of cancer treatment on fertility was discussed with 63% of patients. Of these, 61% were judged to be at high or medium risk of fertility problems. Discussions took place more commonly with boys than girls; the commonest reason for discussion not occurring was young age. The majority (83%) of post-pubertal boys assessed as high/medium risk of infertility were referred for semen cryopreservation. This rate fell to 39% of those in early puberty. Only 1% (n=4) of girls were referred to an assisted conception unit. CONCLUSIONS: These data indicate a high awareness of the potential adverse effects of therapy on fertility among UK paediatric oncologists. High referral rates for older boys indicate that current guidelines are followed, but there is a need for fertility preservation techniques for girls and younger boys.

Iodothyronine deiodinase enzyme activities in bone.

Euthyroid status is essential for normal skeletal development and maintenance of the adult skeleton, but the mechanisms which control supply of thyroid hormone to bone cells are poorly understood. Thyroid hormones enter target cells via monocarboxylate transporter-8 (MCT8), which provides a functional link between thyroid hormone uptake and metabolism in the regulation of T3-action but has not been investigated in bone. Most circulating active thyroid hormone (T3) is derived from outer ring deiodination of thyroxine (T4) mediated by the type 1 deiodinase enzyme (D1). The D2 isozyme regulates intra-cellular T3 supply and determines saturation of the nuclear T3-receptor (TR), whereas a third enzyme (D3) inactivates T4 and T3 to prevent hormone availability and reduce TR-saturation. The aim of this study was to determine whether MCT8 is expressed in the skeleton and whether chondrocytes, osteoblasts and osteoclasts express functional deiodinases. Gene expression was analyzed by RT-PCR and D1, D2 and D3 function by sensitive and highly specific determination of enzyme activities. MCT8 mRNA was expressed in chondrocytes, osteoblasts and osteoclasts at all stages of cell differentiation. D1 activity was undetectable in all cell types, D2 activity was only present in mature osteoblasts whereas D3 activity was evident throughout chondrocyte, osteoblast and osteoclast differentiation in primary cell cultures. These data suggest that T3 availability especially during skeletal development may be limited by D3-mediated catabolism rather than by MCT8 mediated cellular uptake or D2-dependent T3 production.

GH replacement reduces increased lipid peroxidation in GH-deficient adults.

BACKGROUND: GH replacement improves numerous metabolic abnormalities in GH-deficient patients; increased lipid peroxidation (LPO) has been observed in GH-deficient patients; however, it is unknown if LPO is influenced by GH replacement. AIM AND METHODS: To evaluate the extent to which GH replacement might reverse the increased LPO in GH-deficient adults and to analyse if this phenomenon might be involved in the improvement of metabolic disturbances due to GH treatment. Serum concentrations of malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA), as an index of LPO, were measured at baseline, and after 12 and 24 months of GH replacement in 40 adult patients with severe GH deficiency (both in adult- and childhood-onset) and in 40 healthy volunteers, matched for sex, age and body mass index (BMI). Correlations were evaluated between LPO and lipids, IGF-I, metalloproteinase-2 and -9 (MMP-2, -9), vascular endothelial growth factor (VEGF), BMI and GH dose. RESULTS: LPO values in GH-deficient patients were several-fold higher than in controls [55.36 +/- 2.27 vs. 4.19 +/- 0.42 nmol/mg protein (mean +/- SEM), P < 0.0001] and decreased significantly over time with GH replacement to 38.61 +/- 2.15 nmol/mg protein (i.e. by approximately 30%), though still remaining markedly elevated compared with controls (P < 0.0001). The proatherogenic lipid profile parameters correlated positively with LPO in the childhood-onset subgroup before GH replacement. GH replacement restored the positive correlation between LPO and age in male patients (r = 0.57, P = 0.013; r = 0.8, P < 0.001, at 12 and 24 months of GH replacement, respectively). CONCLUSIONS: GH replacement partially reverses the grossly abnormal LPO in GH-deficient adults. It is highly probable, therefore, that oxidative mechanisms are involved in the overall improvement of metabolic changes due to GH replacement.

Growth hormone replacement throughout life: insights into age-related responses to treatment.

The adult growth hormone deficiency (GHD) syndrome is a well-defined clinical entity. Although the symptoms of GHD are not age specific, their relative importance differs depending on the patient's age, and the impact of GHD varies throughout adult life. Ceasing growth hormone (GH) therapy soon after final height in patients with severe GHD potentially limits somatic development by reducing accrual of bone and muscle mass. It is now recognized that the continuation of GH therapy in the transition years is required to achieve adult levels of somatic development. In middle age, the most worrying feature of GHD is the increase in cardiovascular risk, an important component of which is GHD-related dyslipidemia. One of the most profound effects of GH therapy in this age group is the durable reduction in cholesterol levels. Elderly GH-deficient patients experience the symptoms of GHD over and above the signs of normal aging. Perhaps most importantly, these patients have impaired quality of life, with fatigue as a major component. Evidence is growing for improved quality of life with GH therapy in the elderly. This review describes the diagnosis, symptoms and treatment of GHD specific to the different age groups.

Treatment of acromegaly improves quality of life, measured by AcroQol.

BACKGROUND: AcroQol is a disease-generated questionnaire, developed to assess quality of life (QOL) in patients with acromegaly. We have previously demonstrated severely impaired QOL in patients with acromegaly and the value of AcroQol in measuring QOL in a cross-sectional study compared with the non-disease-specific generic tools 'Psychological general wellbeing schedule' (PGWBS) and EuroQol (EQ-5D), and the disease-specific signs and symptoms score (SSS). AIM, SUBJECTS AND METHODS: We re-evaluated these tools in a longitudinal study of 56 of the previously reported patients (33 male, mean age 55 +/- 15 years), in order to determine change in QOL over time and the effect of different treatment modalities. Data were analysed using Spearman's correlation tests. RESULTS: Baseline median IGF-I was 354 ng/ml (range 48-899) and at re-evaluation 217 ng/ml (60-594) (P < 0.001) [median time interval 608 days (113-1136)]. Analysis of change in IGF-I levels and AcroQol scores demonstrated a significant negative correlation (i.e. a reduction in IGF-I being associated with improved overall QOL (r = -0.36, P = 0.006). Significant negative correlations were also seen in the physical (r = -0.33, P = 0.01), psychological (r = -0.37, P = 0.005) and appearance (r = -0.42, P = 0.001) AcroQol subdomains. No correlations were seen between change in IGF-I and change in overall PGWBS score or subdomains, SSS or EQ-5D. CONCLUSIONS: In summary, of the tools studied we have demonstrated AcroQol to be uniquely capable of detecting changes in QOL associated with treatment-induced improvement in the main biochemical marker of disease activity in patients with acromegaly. Further studies are required to evaluate the long-term biological significance of the changes seen in AcroQol.