Biochemical investigations in diagnosis and follow up of acromegaly

Pitfalls in the lab assessment of hypopituitarism

The diagnostic approach to hypopituitarism involves many disciplines. Clinical symptoms rarely are specific. Imaging techniques are helpful but cannot prove the specific functional defects. Therefore, the definitive diagnosis of pituitary insufficiency is largely based on laboratory tests. However, also laboratory methods come with inherent limitations, and it is essential for the clinician to know and recognize typical pitfalls. Most factors potentially impairing the quality of hormone measurements are introduced in the preanalytical phase, i.e. before the hormones are measured by the laboratory. For example, the timing of blood drawing with respect to circadian rhythm, stress, and medication can have an influence on hormone concentrations. During the actual analysis of the hormones, cross-reactions with molecules present in the sample presenting the same or similar epitopes than the intended analyte may affect immunoassays. Interference can also come from heterophilic or human anti-animal antibodies. Unexpected problems can also be due to popular nutritional supplements which interfere with the measurement procedures. An important example in this respect is the interference from biotin. It became only clinically visible when the use of this vitamin became popular among patients. The extreme serum concentrations reached when patients take it as a supplement can lead to incorrect measurements in immunoassays employing the biotin-streptavidin system. To some extent, hormone analyses using liquid chromatography mass spectrometry (LCMS) can overcome problems, although availability and cost-effectiveness of this method still imposes restrictions. In the post-analytical phase, appropriateness of reference intervals and cut-offs with respect to the specific analytical method used is of outmost importance. Furthermore, for interpretation, additional biological and pharmacological factors like BMI, age and concomitant diseases must be considered to avoid misinterpretation of the measured concentrations. It is important for the clinician and the laboratory to recognize when one or more laboratory values do not match the clinical picture. In an interdisciplinary approach, the search for the underlying cause should be initiated.

Pseudoacromegaly-A challenging entity in the endocrine clinic: A systematic review

OBJECTIVE

Pseudoacromegaly encompasses conditions with features of acromegaly/gigantism, but no growth hormone (GH) or insulin-like growth factor-1 (IGF-1) excess. We aimed to review published pseudoacromegaly cases evaluated due to clinical suspicion of acromegaly.

DESIGN/PATIENTS

PubMed/Medline search was conducted to identify reported pseudoacromegaly cases, which were systematically reviewed to ensure they met eligibility criteria: (1) presentation suggestive of acromegaly; (2) acromegaly excluded based on normal GH, IGF-1 and/or GH suppression on oral glucose tolerance test (OGTT-GH); (3) diagnosis of the pseudoacromegaly condition was established. Data were retrieved from each case and analysed collectively.

RESULTS

Of 76 cases, 47 were males, mean ages at presentation and at first acromegaloid symptoms were 28 ± 16 and 17 ± 10 years, respectively. Most common conditions were pachydermoperiostosis (47%) and insulin-mediated pseudoacromegaly (IMP) (24%). Acromegaloid facies (75%) and acral enlargement (80%) were the most common features. Measurement of random GH was reported in 65%, IGF-1 in 79%, OGTT-GH in 51%. GH excess was more frequently excluded based on two tests (53%). Magnetic resonance imaging (MRI) was performed in 30 patients, with pituitary adenoma or hyperplasia being reported in eight and three patients, respectively. Investigations differed between cases managed by endocrine and non-endocrine specialists, the former requesting more often IGF-1, OGTT-GH and pituitary MRI.

CONCLUSIONS

Pseudoacromegaly is a challenging entity that may be encountered by endocrinologists. Pachydermoperiostosis and IMP are the conditions most often mimicking acromegaly. Adequate assessment of GH/IGF-1 is crucial to exclude acromegaly, which may be better performed by endocrinologists. Pituitary incidentalomas are common and require careful judgement to prevent unnecessary pituitary surgery.

Effect of Cabergoline on weight and glucose metabolism in patients with acromegaly

PURPOSE

Cabergoline (CAB) has shown to have benefic effects on the metabolism in different clinical settings but its metabolic role in acromegaly disease has not been studied yet. Aim of our study was to evaluate the impact of CAB on glucose metabolism and weight in patients with acromegaly.

METHODS

All patients with acromegaly undergoing continuous treatment with CAB for at least 6 months were retrospectively screened. Exclusion criteria were discontinuation of CAB for more than one month, change of antidiabetic or other therapy for acromegaly, concomitant untreated hormonal deficiency, initiation of pregnancy and/or breastfeeding. All patients were evaluated in terms of biochemical disease control, glucose metabolism and weight at baseline (T0) and after the introduction of CAB therapy at 6 (T6) and 12 months (T12).

RESULTS

Twenty-six patients (15 females and 11 males) were evaluated at T0 and T6 and 19 patients (12 females and 7 males) were also evaluated at T12. Insulin-like growth factor I (IGF-I) and prolactin (PRL) levels were significantly lower at T6 and T12 compared to baseline (p < 0.001 for IGF-I, p < 0.05 for PRL) even if no further differences were observed between T12 and T6. Considering the entire cohort, no differences were appreciated regarding the metabolic parameters but a significant reduction in weight and body mass index (BMI) was observed at both T6 (p = 0.009 for weight, p = 0.021 for BMI) and T12 (p = 0.014 for weight, p = 0.017 for BMI) compared to baseline.

CONCLUSION

Our results confirm the efficacy of CAB in providing a significant improvement in the biochemical disease control but do not demonstrate a marked benefit on glucose metabolism of acromegaly patients. In such patients, CAB appears to have a rapid effect on weight and BMI, with significant changes noticeable as early as 6 months and persisting for at least 12 months.

Interpreting growth hormone and IGF-I results using modern assays and reference ranges for the monitoring of treatment effectiveness in acromegaly

Standard treatment for acromegaly focuses on the achievement of target absolute levels of growth hormone (GH) and insulin-like growth factor (IGF-I). The appropriateness of these targets when measured using modern assay methods is not well defined. This paper reviews biochemical status assessed using methods available at the time and associated clinical outcomes. GH measurements were shown to provide an indication of changes in tumor size, and failure of GH suppression after glucose stimulation is associated with tumor recurrence. IGF-I levels were more closely associated with changes in symptoms and signs. Reduced GH and IGF-I concentrations were shown to be associated with increased longevity, although the degree of increase has only been analyzed for GH. Lowering of GH and IGF-I has consistently been associated with improved outcomes; however, absolute levels reported in previous studies were based on results from methods and reference ranges that are now obsolete. Applying previously described absolute thresholds as targets (e.g. "normal" IGF-I level) when using current methods is best applied to those with active acromegaly symptoms who could benefit from further lowering of biochemical markers. In asymptomatic individuals with mild IGF-I or GH elevations, targeting biochemical "normalization" would result in the need for combination pharmacotherapy in many patients without proven benefit. Measurement of both GH and IGF-I remains an essential component of diagnosis and monitoring the effectiveness of treatment in acromegaly; however, treatment goals based only on previously identified absolute thresholds are not appropriate without taking into account the assay and reference ranges being employed. Treatment goals should be individualized considering biochemical improvement from an untreated baseline, symptoms of disease, risks, burdens and costs of complex treatment regimens, comorbidities, and quality of life.

Delving into Acromegaly

Acromegaly is a rare and disabling disease with some distinct and striking clinical features that have fascinated (and frightened) laypeople and medical experts alike throughout history [...].

Sex difference in patients with controlled acromegaly-A multicentre survey

OBJECTIVE

Active acromegaly is subject to sex differences in growth hormone (GH) and Insulin like growth factor 1 (IGF-I) patterns as well as clinical features but whether this also pertains to controlled disease is unclear.

DESIGN

In a cross-sectional, multi-centre study, 84 patients with acromegaly (F = 43, M = 41), who were considered controlled after surgery alone (n = 23) or during continued somatostatin receptor ligand (SRL) treatment (n = 61), were examined.

METHODS

Serum concentrations of GH, insulin, glucose and free fatty acid (FFA) were measured during an oral glucose tolerance test (OGTT) together with baseline serum IGF-I and completion of two HR-Qol questionnaires (acromegaly quality of life questionnaire [AcroQol] and Patient-assessed Acromegaly Symptom Questionnaire [PASQ]).

RESULTS

The mean age at the time of the study was 57 (±1.1) years and the majority of females (were postmenopausal. Females had significantly higher fasting GH but comparable IGF-I standard deviation scores (SDS). Using fasting GH < 1.0 µg/L as cut off, disease control was less prevalent in females (F: 56% vs. M: 83%, p = .007) whereas a comparable figure was observed using IGF-I SDS < 2 (F:79% vs. M:76%, p = .71). Compared with males, female patients showed impaired AcroQol physical score (p = .05), higher fasting FFA (p = .03) and insulin concentrations during the OGTT (p = .04).

CONCLUSION

In patients with acromegaly considered controlled, postmenopausal females exhibited higher GH levels than males despite comparable IGF-I levels, which also translated into impaired metabolic health and well-being. Our findings point to the relevance of including GH measurements in the assessment of disease control and suggest that disease-specific sex differences prevail after treatment.

Acromegaly: pathogenesis, diagnosis, and management

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

The biochemical diagnosis of acromegaly: revising the role of measurement of IGF-I and GH after glucose load in 5 questions

INTRODUCTION

Acromegaly is a rare disorder characterized by the excessive secretion of growth hormone (GH), mostly caused by pituitary adenomas. While in full-blown cases the diagnosis is easy to establish, milder cases are more challenging. Additionally, establishing whether full cure after surgery is reached may be difficult.

AREAS COVERED

In this article, we will review the challenges posed by the variability in measurements of GH and its main effector insulin-like growth factor I (IGF-I) due to both biological changes, co-morbidities, and assays variability.

EXPERT OPINION

Interpretation of GH and IGF-I assays is important in establishing an early diagnosis of acromegaly, in avoiding misdiagnosis, and in establishing if cure is achieved by surgery. Physicians should be familiar with the variables that affect measurements of these 2 hormones, and with the performance of the assays available in their practice.

Characteristics and treatment outcomes of micromegaly - acromegaly with apparently normal basal GH: A retrospective study and literature review

Objective. Micromegaly describes a subgroup of patients with clinically evident acromegaly and elevated insulin-like growth factor I (IGF-I) with apparently normal basal growth hormone (bGH) and often a glucose-suppressed growth hormone (GH) of <1 ng/mL at diagnosis. It is controversial whether this condition is a distinct clinical entity or a classic acromegaly in early stages. The aim of the present article was to characterize the prevalence, clinical and biochemical characteristics, and therapeutic outcomes of micromegaly. Methods. A retrospective study of patients with an acromegaly followed ≥1 year at a tertiary center from 1995 to 2019. Patients without IGF-I or GH measurements at diagnosis were excluded. At diagnosis, bGH was considered normal if <2 ng/mL. Results. From 74 patients with acromegaly, 6 (8.1%) had normal bGH levels. There was no difference in the gender distribution, median diagnostic delay, and follow-up time between patients with normal bGH and elevated bGH. Patients with normal bGH were significantly older at time of the first acromegalic manifestation and diagnosis they had significantly lower nadir post-glucose GH and IGF-I levels, and tended to have a higher prevalence of obesity than patients with the elevated bGH. The frequency of acromegalic symptoms, signs, and other comorbidities than obesity was similar between groups. Five patients (83.3%) with normal bGH presented microadenomas. Post-operative remission and outcomes at last visit were comparable between patients with or without normal bGH. Conclusions. Normal bGH acromegaly is relatively uncommon in our patients. These patients showed differentiating characteristics from the classical acromegaly with elevated bGH. Further studies are needed to extend the knowledge about its clinical behavior, therapeutic outcomes, morbidity, and mortality.

Diagnosis and Treatment of Acromegaly: An Update

Acromegaly is typically caused by a growth hormone-secreting pituitary adenoma, driving excess secretion of insulin-like growth factor 1. Acromegaly may result in a variety of cardiovascular, respiratory, endocrine, metabolic, musculoskeletal, and neoplastic comorbidities. Early diagnosis and adequate treatment are essential to mitigate excess mortality associated with acromegaly. PubMed searches were conducted using the keywords growth hormone, acromegaly, pituitary adenoma, diagnosis, treatment, pituitary surgery, medical therapy, and radiation therapy (between 1981 and 2021). The diagnosis of acromegaly is confirmed on biochemical grounds, including elevated serum insulin-like growth factor 1 and lack of growth hormone suppression after glucose administration. Pituitary magnetic resonance imaging is advised in patients with acromegaly to identify an underlying pituitary adenoma. Transsphenoidal pituitary surgery is generally first-line therapy for patients with acromegaly. However, patients with larger and invasive tumors (macroadenomas) are often not in remission postoperatively. Medical therapies, including somatostatin receptor ligands, cabergoline, and pegvisomant, can be recommended to patients with persistent disease after surgery. Select patients may also be candidates for preoperative medical therapy. In addition, primary medical therapy has a role for patients without mass effect on the optic chiasm who are unlikely to be cured by surgery. Clinical, endocrine, imaging, histologic, and molecular markers may help predict the response to medical therapy; however, confirmation in prospective studies is needed. Radiation therapy is usually a third-line option and is increasingly administered by a variety of stereotactic techniques. An improved understanding of the pathogenesis of acromegaly may ultimately lead to the design of novel, efficacious therapies for this serious condition.

Acromegaly: Clinical Care in Central and Eastern Europe, Israel, and Kazakhstan

Acromegaly is a rare condition typically caused by benign pituitary adenomas, resulting in excessive production of growth hormone. Clinical manifestations of acromegaly are diverse, varying from the overgrowth of body tissue to cardiovascular, metabolic, and osteoarticular disorders. Symptoms may emerge slowly, overlapping with other diseases and often involve many different healthcare specialists. In the last decade, efforts to provide an accurate and timely diagnosis of acromegaly have improved disease management and clinical experience. Despite this progress, marked differences in the diagnosis, treatment, and management of acromegaly exist from country-to-country. To address these inconsistencies in the region comprising Central and Eastern Europe, Israel, and Kazakhstan, a panel of acromegaly experts from 13 of these countries was convened. Acromegaly experts from each country provided available information on the approaches from their country, including regional treatment centers and multidisciplinary teams, treatment access, reimbursement and availability, and physician education, disease awareness, and patient advocacy. Across several areas of acromegaly management, divergent approaches were identified and discussed, including the provision of multidisciplinary care, approved and available treatments, and disease awareness programs. These were recognized as areas of potential improvement in the management of acromegaly, in addition to participation in national and regional acromegaly registries. Further experience exchange will facilitate the identification of specific strategies that can be adapted in each country, and widespread participation in acromegaly registries will enable their evaluation. It is anticipated that this approach will support the optimization of acromegaly patient care across this region.

Soluble Alpha Klotho in Acromegaly: Comparison With Traditional Markers of Disease Activity

CONTEXT

Soluble alpha klotho (sαKL) has been linked to growth hormone (GH) action, but systematic evaluation and comparisons with traditional biomarkers in acromegaly are lacking.

OBJECTIVE

To evaluate the potential of sαKL to aid classification of disease activity.

METHODS

This retrospective study at 2 academic centers included acromegaly patients before surgery (A, n = 29); after surgery (controlled, discordant, or uncontrolled) without (B1, B2, B3, n = 28, 11, 8); or with somatostatin analogue treatment (C1, C2, C3, n = 17, 11, 5); nonfunctioning pituitary adenomas (n = 20); and healthy controls (n = 31). sαKL was measured by immunoassay and compared with traditional biomarkers (random and nadir GH, insulin-like growth factor I [IGF-I], IGF binding protein 3). Associations with disease activity were assessed.

RESULTS

sαKL was correlated to traditional biomarkers, particularly IGF-I (rs=0.80, P <0.0001). High concentrations before treatment (A, median, interquartile range: 4.04 × upper limit of normal [2.26-8.08]) dropped to normal after treatment in controlled and in most discordant patients. A cutoff of 1548 pg/mL for sαKL discriminated controlled (B1, C1) and uncontrolled (B3, C3) patients with 97.8% (88.4%-99.9%) sensitivity and 100% (77.1%-100%) specificity. sαKL was below the cutoff in 84% of the discordant subjects. In the remaining 16%, elevated sαKL and IGF-I persisted, despite normal random GH. Sex, age, body mass index, and markers of bone and calcium metabolism did not significantly affect sαKL concentrations.

CONCLUSION

Our data support sαKL as a biomarker to assess disease activity in acromegaly. sαKL exhibits close association with GH secretory status, large dynamic range, and robustness toward biological confounders. Its measurement could be helpful particularly when GH and IGF-I provide discrepant information.

The Biochemical Diagnosis of Acromegaly

Background: The diagnosis of acromegaly still poses a clinical challenge, and prolonged diagnostic delay is common. The most important assays for the biochemical diagnosis and management of acromegaly are growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Objective: Discuss the role of IGF-1, basal serum GH, and nadir GH after oral glucose tolerance test (OGTT) for the diagnosis, management, and treatment of patients with acromegaly. Methods: We performed a narrative review of the published data on the biochemical diagnosis and monitoring of acromegaly. An English-language search for relevant studies was conducted on PubMed from inception to 1 January 2021. The reference lists of relevant studies were also reviewed. Results: Serum IGF-1 levels, basal GH values, and nadir GH after OGTT play a major role in the diagnosis, management, and treatment of patients with acromegaly. Measurement of IGF-1 levels is the key factor in the diagnosis and monitoring of acromegaly, but basal and nadir GH following OGTT are also important. However, several factors may significantly influence the concentrations of these hormones, including assay methods, physiologic and pathologic factors. In some cases, discordant GH and IGF-1 levels may be challenging and usually requires additional data and monitoring. Conclusion: New GH and IGF-1 standards are much more precise and provide more accurate tools to diagnose and monitor patients with acromegaly. However, all these biochemical tools have their limitations, and these should be taken under consideration, along with the history, clinical features and imaging studies, when assessing patients for acromegaly.

Multidisciplinary management of acromegaly: A consensus

The 13th Acromegaly Consensus Conference was held in November 2019 in Fort Lauderdale, Florida, and comprised acromegaly experts including endocrinologists and neurosurgeons who considered optimal approaches for multidisciplinary acromegaly management. Focused discussions reviewed techniques, results, and side effects of surgery, radiotherapy, and medical therapy, and how advances in technology and novel techniques have changed the way these modalities are used alone or in combination. Effects of treatment on patient outcomes were considered, along with strategies for optimizing and personalizing therapeutic approaches. Expert consensus recommendations emphasize how best to implement available treatment options as part of a multidisciplinary approach at Pituitary Tumor Centers of Excellence.

Pituitary Tumors Centers of Excellence

Pituitary tumors are common and require complex and sophisticated procedures for both diagnosis and therapy. To maintain the highest standards of quality, it is proposed to manage patients in pituitary tumors centers of excellence (PTCOEs) with patient-centric organizations, with expert clinical endocrinologists and neurosurgeons forming the core. That core needs to be supported by experts from different disciplines such as neuroradiology, neuropathology, radiation oncology, neuro-ophthalmology, otorhinolaryngology, and trained nursing. To provide high-level medical care to patients with pituitary tumors, PTCOEs further pituitary science through research publication, presentation of results at meetings, and performing clinical trials.

Octreotide-Resistant Acromegaly: Challenges and Solutions

Acromegaly is a rare and severe disease caused by an increased and autonomous secretion of growth hormone (GH), thus resulting in high circulating levels of insulin-like growth factor 1 (IGF-1). Comorbidities and mortality rate are closely related to the disease duration. However, in most cases achieving biochemical control means reducing or even normalizing mortality and restoring normal life expectancy. Current treatment for acromegaly includes neurosurgery, radiotherapy and medical therapy. Transsphenoidal surgery often represents the recommended first-line treatment. First-generation somatostatin receptor ligands (SRLs) are the drug of choice in patients with persistent disease after surgery and are suggested as first-line treatment for those ineligible for surgery. However, only about half of patients treated with octreotide (or lanreotide) achieve biochemical control. Other available drugs approved for clinical use are the second-generation SRL pasireotide, the dopamine agonist cabergoline, and the GH-receptor antagonist pegvisomant. In the present paper, we revised the current literature about the management of acromegaly, aiming to highlight the most relevant and recent therapeutic strategies proposed for patients resistant to first-line medical therapy. Furthermore, we discussed the potential molecular mechanisms involved in the variable response to first-generation SRLs. Due to the availability of different medical therapies, the choice for the most appropriate drug can be currently based also on the peculiar clinical characteristics of each patient.

Random Gh and Igf-I levels after transsphenoidal surgery for acromegaly: relation with long-term remission

PURPOSE

To evaluate the role of IGF-I and random GH measurements 3 months after transsphenoidal surgery (TSS) in predicting long-term remission in acromegaly patients.

METHODS

Retrospective analysis of 54 acromegaly patients who underwent TSS with the same neurosurgery team. Random GH and IGF-I values evaluated 3 months after TSS were related to long-term outcomes. The initiation of adjuvant therapy at any time defined surgical failure.

RESULTS

At 3 months, 14 (25.9%) patients had controlled disease (CD; normal IGF-I and GH < 1.0 µg/L), 25 (46.3%) had uncontrolled disease (UD; high IGF-I and GH), and 15 (27.8%) had biochemical discrepancies (BD): 12 BDI (normal IGF-I + GH ≥ 1.0 μg/L) and 3 BDII (high IGF-I + GH < 1.0 μg/L). All patients of the CD group, 2 of the UD, 11 of the BDI, and 2 of the BDII, progressed with long-term remission and had IGF-I ≤ 1.25-fold the Upper Limit of Normal (ULN), in contrast with all cases of surgical failure where IGF-I was ≥1.3-fold ULN. Only one patient with normal IGF-I had recurrence, resulting in 100% sensitivity and 96% specificity of post-surgical IGF-I ≤ 1.25-fold ULN to predict long-term remission, observed in 54% of our cohort. Post-surgical random GH ≥ 1.7 µg/L was the best cutoff to identify surgical failure, but its accuracy to predict long-term outcomes was limited.

CONCLUSIONS

IGF-I levels ≤ 1.25-fold ULN 3 months after TSS was the best guide for long-term remission in acromegaly patients with both initial surgical failure and discrepant biochemical results.

Model informed quantification of the feed-forward stimulation of growth hormone by growth hormone-releasing hormone

Aims

Growth hormone (GH) secretion is pulsatile and secretion varies highly between individuals. To understand and ultimately predict GH secretion, it is important to first delineate and quantify the interaction and variability in the biological processes underlying stimulated GH secretion. This study reports on the development of a population nonlinear mixed effects model for GH stimulation, incorporating individual GH kinetics and the stimulation of GH by GH‐releasing hormone (GHRH).

Methods

Literature data on the systemic circulation, the median eminence, and the anterior pituitary were included as system parameters in the model. Population parameters were estimated on data from 8 healthy normal weight and 16 obese women who received a 33 μg recombinant human GH dose. The next day, a bolus injection of 100 μg GHRH was given to stimulate GH secretion.

Results

The GH kinetics were best described with the addition of 2 distribution compartments with a bodyweight dependent clearance (increasing linearly from 24.7 L/h for a 60‐kg subject to 32.1 L/h for a 100‐kg subject). The model described the data adequately with high parameter precision and significant interindividual variability on the GH clearance and distribution volume. Additionally, high variability in the amount of secreted GH, driven by GHRH receptor activation, was identified (coefficient of variation = 90%).

Conclusion

The stimulation of GH by GHRH was quantified and significant interindividual variability was identified on multiple parameters. This model sets the stage for further development of by inclusion of additional physiological components to quantify GH secretion in humans.

Acromegaly with congenital generalized lipodystrophy - two rare insulin resistance conditions in one patient: a case report

BACKGROUND

Lipodystrophies are a group of diseases which are characterized by abnormal adipose tissue deposition and are frequently associated with metabolic changes. Congenital generalized lipodystrophy is an autosomal recessive syndrome, with a prevalence < 1:10 million. Acromegaly is a rare disease, secondary to the chronic hypersecretion of growth hormone and insulin-like growth factor-1, with characteristic metabolic and somatic effects. "Acromegaloidism" is a term used for patients who manifest clinical features of acromegaly, but do not present a demonstrable hormone growth hypersecretion. The extreme shortage of subcutaneous adipose tissues and muscle hypertrophy confer an acromegaloid-like appearance in these patients.

CASE PRESENTATION

We describe a case of a patient with the rare combination of Berardinelli-Seip congenital lipodystrophy and acromegaly; our patient is a 63-year-old white man, who was referred to an endocrinology consultation for suspected lipodystrophy. He had lipoatrophy of upper and lower limbs, trunk, and buttocks, with muscular prominence, acromegaloid facial appearance, large extremities, and soft tissue tumescence. In addition, he had dyslipidemia and prediabetes. His fat mass ratio (% trunk fat mass/% lower limbs fat mass) was 1.02 by densitometry and he also had hepatomegaly, with mild steatosis (from an abdominal ultrasound), and left ventricular hypertrophy (from an electrocardiogram). His first oral glucose tolerance test had growth hormone nadir of 0.92 ng/mL, and the second test, 10 months afterwards, registered growth hormone nadir of 0.64 ng/mL (growth hormone nadir < 0.3 ng/mL excludes acromegaly). Pituitary magnetic resonance imaging identified an area of hypocaptation of contrast product in relation to a pituitary adenoma and he was subsequently submitted to transsphenoidal surgical resection of the mass. A pathological evaluation showed pituitary adenoma with extensive expression of growth hormone and adrenocorticotropic hormone, as well as a rare expression of follicle-stimulating hormone and prolactin. A genetic study revealed an exon 3/exon 4 deletion of the AGPAT2 gene in homozygosity.

CONCLUSIONS

Congenital generalized lipodystrophy is a rare disease which occurs with acromegaloid features. As far as we know, we have described the first case of genetic lipodystrophy associated with true acromegaly. Although this is a rare association, the presence of congenital generalized lipodystrophy should not exclude the possibility of simultaneous acromegaly.

Italian Association of Clinical Endocrinologists (AME) and Italian AACE Chapter Position Statement for Clinical Practice: Acromegaly - Part 1: Diagnostic and Clinical Issues

Acromegaly is a rare disease. Improvements in lifespan in these patients have recently been reported due to transsphenoidal surgery (TSS), advances in medical therapy, and strict criteria for defining disease remission. This document reports the opinions of a group of Italian experts who have gathered together their prolonged clinical experience in the diagnostic and therapeutic challenges of acromegaly patients. Both GH and IGF-I (only IGF-I in those treated with Pegvisomant) are needed in the diagnosis and follow-up. Comorbidities (cardio-cerebrovascular disease, sleep apnea, metabolic derangement, neoplasms, and bone/joint disease) should be specifically addressed. Any newly diagnosed patient should be referred to a multidisciplinary team experienced in the treatment of pituitary adenomas.

The tendency of reduced periodontal destruction in acromegalic patients showing similar inflammatory status with periodontitis patients

PURPOSE

Evaluate periodontal status of acromegalics through clinical and biochemical variables.

METHODS

Demographics, hormone and metabolic variables, periodontal variables, gingival crevicular fluid (GCF) volume, and content data were collected from 30 patients with acromegaly, 30 patients with periodontitis, and 20 healthy subjects and comparatively analyzed.

RESULTS

GH differences between acromegaly (2.56 ± 4.86) and periodontitis (0.53 ± 0.95) (p < 0.001) were statistically significant. IGF-1 was lowest at periodontitis (113.31 ± 45.01) and lower (152.11 ± 45.56) at healthy group compared with acromegalics (220.38 ± 167.62) (p < 0.05). GH and IGF-1 had positive correlation (p < 0.05). IGF-1 and CAL had negative (p < 0.01) correlation except healthy group that showed the same correlation at the opposite direction (p < 0.05). Besides similar plaque and gingival indices with periodontitis, acromegalics showed relatively less CAL and GCF volume but except CAL, all their periodontal variables were higher than healthy subjects. GCF GH and prolactin showed higher values in acromegalics while healthy subjects showed relatively high interleukin-1, -10 and carboxyterminal telopeptide of type I collagen compared with others.

CONCLUSION

Acromegalics have a tendency of slowed periodontal destruction with an influence of GH and IGF-1 to the inflammation- and collage metabolism-related mechanisms rather than bone-associated ones. However, this information must be confirmed with further studies exploring the mechanisms possibly bonded to others.

Laboratory investigations in the diagnosis and follow-up of GH-related disorders

In addition to auxiological, clinical and metabolic features measurements of growth hormone (GH) and insulin-like growth factor I (IGF-I) complement our tools in diagnosis and follow-up of GH-related disorders. While comparably robust during the pre-analytical phase, measurement and interpretation of concentrations of both hormones can be challenging due to analytical issues and biological confounders. Assay methods differ in terms of antibody specificity, interference from binding proteins, reference preparations and sensitivity. GH assays have different specificity towards different GH-isoforms (e.g. 20 kDa GH, placental GH) and interference from the GH antagonist Pegvisomant. The efficacy to prevent binding protein interference is most important in IGF-I assays. Methodological differences between assays require that reference intervals and diagnostic cut-offs are assay-specific. Among biological variables, pubertal development and age are most relevant for IGF-I, making detailed reference intervals mandatory for interpretation. GH has pulsatile secretion and short half-life. Its concentration is modified by acute factors such as stress, exercise and sleep, but also by intake of oral estrogens and anthropometric factors (e.g. BMI). Other GH dependent biomarkers such as free IGF-I, IGF binding protein 3 (IGFBP 3) and acid labile subunit (ALS) have been proposed. Their concentrations largely mirror the information obtained through measurement of IGF-I, but their measurement can be helpful in particular situations. In this review, we describe the evolution of analytical methods to measure biomarkers of GH action, the impact of the methodological changes on laboratory results and the need to include biological variables in their interpretation. Arch Endocrinol Metab. 2019;63(6):618-29.

Current perspectives on the impact of clinical disease and biochemical control on comorbidities and quality of life in acromegaly

Acromegaly is a rare chronic, systemic disorder caused by excessive growth hormone (GH) secretion from a somatotroph pituitary adenoma. GH hypersecretion leads to overproduction of insulin-like growth factor-1 (IGF-1), which contributes to the somatic overgrowth, physical disfigurement, onset of multiple systemic comorbidities, reduced quality of life (QoL) and premature mortality of uncontrolled patients. Somatostatin receptor ligands, dopamine agonists and a GH receptor antagonist are currently available for medical therapy of acromegaly. The main aim of treatment is biochemical normalisation, defined as age-normalised serum IGF-1 values and random GH levels <1.0 μg/L. However, there is an increasing evidence suggesting that achieving biochemical control does not always decrease the burden of disease-related comorbidities and/or improve patients' QoL. This lack of correlation between biochemical and clinical control can be due to both disease duration (late diagnosis) or to the peculiarity of a given comorbidity. Herein we conducted ad hoc literature searches in order to find the most recent and relevant reports on biochemical and clinical disease control during medical treatment of acromegaly. Particularly, we analyse and describe the relationship between biochemical, as well as clinical disease control in patients with acromegaly receiving medical therapy, with a focus on comorbidities and QoL. In conclusion, we found that current literature data seem to indicate that clinical disease control (besides biochemical control), encompassing clinical signs and symptoms, comorbidities and QoL, emerge as a primary focus of acromegaly patient management.

Clinical Characteristics of Acromegalic Patients With Paradoxical GH Response to Oral Glucose Load

CONTEXT

A paradoxical GH response to oral glucose (OG) is often found in acromegaly. However, the clinical characteristics of patients with acromegaly and a paradoxical GH response to OG (OG responders) remain unclear.

OBJECTIVE

The aim of the present study was to define the clinical characteristics of OG responders with acromegaly.

DESIGN

Retrospective study.

SETTING

Hospitalized care at Osaka University Hospital.

PATIENTS AND METHODS

Of 63 patients with acromegaly admitted to our hospital from January 2006 to January 2017, 19 were classified as OG responders and 44 as nonresponders. The clinical characteristics of these groups were compared.

RESULTS

Before surgery, OG responders had substantially greater IGF-1 SD scores than nonresponders (P < 0.05), although no difference was found in basal GH levels between the two groups (P = 0.46). Regarding glucose metabolism, 120-minute plasma glucose and immunoreactive insulin after OG administration and hemoglobin A1c were significantly greater in OG responders than in nonresponders (P < 0.01, P < 0.05, P < 0.05, respectively). GH levels during octreotide or bromocriptine testing were decreased more significantly in OG responders than in nonresponders (P < 0.05, P < 0.05, respectively). The proportion of pituitary tumors with hypointensity on T2-weighted MRI was significantly greater in OG responders than in nonresponders (P < 0.05). The difference in IGF-1 and parameters of glucose metabolism described disappeared between the two groups after surgery.

CONCLUSIONS

The paradoxical GH response reflected the clinical characteristics, especially IGF-I level, glucose metabolism, and drug efficacy in acromegaly. A paradoxical GH response, in addition to the nadir GH levels, to OG load is potentially useful for evaluation of the clinical characteristics of acromegaly.

A Consensus Statement on acromegaly therapeutic outcomes

The 11th Acromegaly Consensus Conference in April 2017 was convened to update recommendations on therapeutic outcomes for patients with acromegaly. Consensus guidelines on the medical management of acromegaly were last published in 2014; since then, new pharmacological agents have been developed and new approaches to treatment sequencing have been considered. Thirty-seven experts in the management of patients with acromegaly reviewed the current literature and assessed changes in drug approvals, clinical practice standards and clinical opinion. They considered current treatment outcome goals with a focus on the impact of current and emerging somatostatin receptor ligands, growth hormone receptor antagonists and dopamine agonists on biochemical, clinical, tumour mass and surgical outcomes. The participants discussed factors that would determine pharmacological choices as well as the proposed place of each agent in the guidelines. We present consensus recommendations highlighting how acromegaly management could be optimized in clinical practice.

Growth hormone: isoforms, clinical aspects and assays interference

The measurement of circulating concentrations of growth hormone (GH) is an indispensable tool in the diagnosis of both GH deficiency and GH excess. GH is a heterogeneous protein composed of several molecular isoforms, but the physiological role of these different isoforms has not yet been fully understood. The 22KD GH (22 K-GH) is the main isoform in circulation, followed by 20KD GH (20 K-GH) and other rare isoforms. Studies have been performed to better understand the biological actions of the different isoforms as well as their importance in pathological conditions. Generally, the non-22 K- and 20 K-GH isoforms are secreted in parallel to 22 K-GH, and only very moderate changes in the ratio between isoforms have been described in some pituitary tumors or during exercise. Therefore, in a diagnostic approach, concentrations of 22 K-GH accurately reflect total GH secretion. On the other hand, the differential recognition of GH isoforms by different GH immunoassays used in clinical routine contributes to the known discrepancy in results from different GH assays. This makes the application of uniform decision limits problematic. Therefore, the worldwide efforts to standardize GH assays include the recommendation to use 22 K-GH specific GH assays calibrated against the pure 22 K-GH reference preparation 98/574. Adoption of this recommendation might lead to improvement in diagnosis and follow-up of pathological conditions, and facilitate the comparison of results from different laboratories.

How are growth hormone and insulin-like growth factor-1 reported as markers for drug effectiveness in clinical acromegaly research? A comprehensive methodologic review

OBJECTIVE

In rare disease research, most randomized prospective clinical trials can only use limited number of patients and are comprised of highly heterogeneous populations. Therefore, it is crucial to report the results in such a manner that it allows for comparison of treatment effectiveness and biochemical control between studies. The aim of this review was to investigate the current methods that are being applied to measure and report growth hormone (GH) and insulin-like growth factor-1 (IGF-1) as markers for drug effectiveness in clinical acromegaly research.

SEARCH STRATEGY

A systematic search of recent prospective and retrospective studies, published between 2012 and 2017, that studied the effects of somatostatin analogues or dopamine agonists in acromegaly patients was performed. The markers of interest were GH, IGF-1, and the suppression of GH after an oral glucose tolerance test (OGTT). Additionally, the use of pharmacokinetic (PK) measurements in these studies was analyzed. The sampling design, cut-off for biochemical control, reported units, and used summary statistics were summarized.

RESULTS

A total of 49 articles were selected out of the 263 screened abstracts. IGF-1 concentrations were measured in all 49 studies, GH in 45 studies, and an OGTT was performed in 11 studies. A wide range of different cut-off values and sampling designs were used to determine biochemical control in acromegaly patients. The summary statistics were reported in various ways, with the percentage of biochemical control most frequently used. Nine studies sampled the PK at one or more time points. Non-compartmental analyses were commonly performed on the available PK data.

CONCLUSIONS

The way GH and IGF-1 are measured and reported in acromegaly research varies considerably. A consensus on how to report study results would enable better comparisons between studies, thereby improving evidence based decision making to optimize treatment in acromegaly.

Silent somatotroph pituitary adenomas: an update

Silent growth hormone adenomas (SGHA) are a rare entity of non-functioning pituitary neuroendocrine tumors. Diagnosis is invariably made post-operatively of a tumor immunopositive for GH (and Pit-1 in selected cases) but without clinical acromegaly. Mainly young females are affected, and tumors are often uncovered by investigation for headaches or oligoamenorrhea. Integration of clinical, pathological and biochemical data is required for proper diagnosis. Beside normal IGF-1 levels, a third of SGHAs displays elevated GH levels and some will eventually progress to acromegaly. Almost two-thirds will be mixed GH-prolactin tumors and sparsely-granulated monohormonal GH tumors seems the more aggressive subtype. Recurrence and need for radiation is higher than other non-functioning tumors so close follow-up is warranted.

Control of (pre)-analytical aspects in immunoassay measurements of metabolic hormones in rodents

The measurement of circulating hormones by immunoassay remains a cornerstone in preclinical endocrine research. For scientists conducting and interpreting immunoassay measurements of rodent samples, the paramount aim usually is to obtain reliable and meaningful measurement data in order to draw conclusions on biological processes. However, the biological variability between samples is not the only variable affecting the readout of an immunoassay measurement and a considerable amount of unwanted or unintended variability can be quickly introduced during the pre-analytical and analytical phase. This review aims to increase the awareness for the factors 'pre-analytical' and 'analytical' variability particularly in the context of immunoassay measurement of circulating metabolic hormones in rodent samples. In addition, guidance is provided how to gain control over these variables and how to avoid common pitfalls associated with sample collection, processing, storage and measurement. Furthermore, recommendations are given on how to perform a basic validation of novel single and multiplex immunoassays for the measurement of metabolic hormones in rodents. Finally, practical examples from immunoassay measurements of plasma insulin in mice address the factors 'sampling site and inhalation anesthesia' as frequent sources of introducing an unwanted variability during the pre-analytical phase. The knowledge about the influence of both types of variability on the immunoassay measurement of circulating hormones as well as strategies to control these variables are crucial, on the one hand, for planning and realization of metabolic rodent studies and, on the other hand, for the generation and interpretation of meaningful immunoassay data from rodent samples.