The ongoing challenge of discrepant growth hormone and insulin-like growth factor I results in the evaluation of treated acromegalic patients: a systematic review and meta-analysis

"Micromegaly": Acromegaly with apparently normal GH, an entity on its own?

A small proportion of the patients with acromegaly present with apparently normal basal GH levels and suppressible GH levels despite increased IGF-1 levels, a pattern called micromegaly by some authors. Whether this pattern represents a distinct entity or is just an expression of acromegaly in its early stages is still a matter of debate. Nevertheless, these patients have some peculiar characteristics such as being more likely older and male, mostly harbour microadenomas or small macroadenomas, and have lower IGF-1 and postglucose GH levels. Even though, the frequency and severity of clinical signs and comorbidities are similar to those of patients with classic acromegaly. In conclusion, micromegaly seems to be a distinct clinical entity with a different biological behavior characterized by a low GH output.

Consensus on criteria for acromegaly diagnosis and remission

PURPOSE

The 14th Acromegaly Consensus Conference was convened to consider biochemical criteria for acromegaly diagnosis and evaluation of therapeutic efficacy.

METHODS

Fifty-six acromegaly experts from 16 countries reviewed and discussed current evidence focused on biochemical assays; criteria for diagnosis and the role of imaging, pathology, and clinical assessments; consequences of diagnostic delay; criteria for remission and recommendations for follow up; and the value of assessment and monitoring in defining disease progression, selecting appropriate treatments, and maximizing patient outcomes.

RESULTS

In a patient with typical acromegaly features, insulin-like growth factor (IGF)-I > 1.3 times the upper limit of normal for age confirms the diagnosis. Random growth hormone (GH) measured after overnight fasting may be useful for informing prognosis, but is not required for diagnosis. For patients with equivocal results, IGF-I measurements using the same validated assay can be repeated, and oral glucose tolerance testing might also be useful. Although biochemical remission is the primary assessment of treatment outcome, biochemical findings should be interpreted within the clinical context of acromegaly. Follow up assessments should consider biochemical evaluation of treatment effectiveness, imaging studies evaluating residual/recurrent adenoma mass, and clinical signs and symptoms of acromegaly, its complications, and comorbidities. Referral to a multidisciplinary pituitary center should be considered for patients with equivocal biochemical, pathology, or imaging findings at diagnosis, and for patients insufficiently responsive to standard treatment approaches.

CONCLUSION

Consensus recommendations highlight new understandings of disordered GH and IGF-I in patients with acromegaly and the importance of expert management for this rare disease.

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.

A combined top-down and bottom-up LC-HRMS/MS method for the quantification of human growth hormone in plasma and serum

OBJECTIVE

The precise and accurate quantification of human growth hormone (GH) in plasma/ serum is crucial for the diagnosis and treatment of diseases like GH deficiency or acromegaly. However, the ligand-binding assays (LBAs) currently used for routine testing show considerable methodological variability. Here, we present a complementary, combined top-down and bottom-up LC-MS-based method to quantify (intact) GH in plasma and serum, which concurrently provides a basis for a MS-based analysis of GH in doping controls.

DESIGN

Extraction of GH from plasma/ serum was accomplished by protein precipitation, followed by an immunocapture step using protein A-coupled magnetic beads and a polyclonal anti-GH antibody. The intact protein was subsequently analyzed top-down on a 2D-LC-HRMS/MS system. In addition, sample extracts were digested with trypsin and analyzed for signal peptides corresponding to 'total', 22 kDa and 20 kDa GH (bottom-up). Both assays were validated according to current guidelines and compared to the GH isoform differential immunoassay used in routine doping control analysis. GH concentrations in serum samples of healthy adults, patients with acromegaly, and in samples obtained after administration of recombinant GH were analyzed as proof-of-principle.

RESULTS

The intact monomeric 22 kDa isoform of GH was selectively quantified in a representative working range of 0.5 to 10 ng/ml by top-down LC-HRMS/MS. Subsequent bottom-up analysis provided additional data on 'total' and 20 kDa GH. Top-down and bottom-up assay results for the 22 kDa isoform correlated well with the corresponding immunoassay results (R2 > 0.95). For a possible application of the method in an anti-doping context, the ratio between 22 kDa and 'total' GH was evaluated, indicating differences between the various donor groups, but only with limited significance.

CONCLUSION

The top-down and bottom-up LC-HRMS/MS method developed here presents a valuable tool for the quantification of GH in plasma/ serum complementary to established LBAs used at present in clinical measurements. Albeit the examination of the GH isoform proportions by the LC-MS method does not yet allow for the assessment of GH abuse, the obtained findings provide an important basis to enable LC-MS-based GH analysis of doping control samples in the future.

Discordant biochemical parameters of acromegaly remission do not influence the prevalence or aggressiveness of metabolic comorbidities: a single-center study

Purpose

The discrepancy between the biomarkers of disease's activity in acromegalic patients (GH and IGF-1) is almost frequent representing a challenge for the development of comorbidities in the long term. The aim of this study was to evaluate the prevalence and severity of metabolic comorbidities (diabetes, hypertension, and dyslipidemia) in surgically treated acromegalic patients with disease control and discordant GH and/or IGF-1 levels compared with those with concordant values.

Patients and methods

Retrospective monocentric observational study on acromegalic surgically treated patients with biochemical remission (group A) or mild discordant GH or IGF-1 levels (group B). Metabolic complications and medical therapy were assessed at diagnosis and at the last follow-up visit. Severity of the disease was set for drug titration or shift to another molecule or more than before.

Results

There were 18 patients that met the inclusion criteria [group A: nine patients; group B: nine patients, follow-up 7 years (IQR 5.0;11.25)]. The prevalence of female patients was significantly higher in the remission group compared with the discordant group (p < 0.02). Considering metabolic complications, at the last follow-up, 61.1% was affected by hypertension, 33.3% by diabetes, and 61.1% by dyslipidemia, without differences between groups. Drug characteristics (dose, shift, number) during the follow-up did not differ significantly between groups.

Conclusion

Metabolic complications, mainly dyslipidemia, are frequent in cured acromegalic patients, but GH/IGF-1 discrepancy does not seem to represent a risk factor for their presence or persistence. More extended studies are needed to confirm our results in a long-term period.

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.

The prevalence of acromegaly is higher than previously reported: Changes over a three-decade period

OBJECTIVE

To study time-related changes in the prevalence and patient characteristics of acromegaly, as well as to assess the impact of changes in treatment on disease control.

METHODS

A total of 107 patients with acromegaly were identified by healthcare registries and subsequently validated by patient chart review over a three-decade period (1992-2021). A systematic literature review focusing on the incidence and prevalence of acromegaly was performed identifying 31 studies.

RESULTS

The prevalence of acromegaly significantly increased throughout the study period (R²  = 0.94, p < .001) and was 122 cases/10⁶ persons in 2021 whereas the annual incidence remained constant at 4.6 cases/10⁶ persons. The age at the first sign of acromegaly and the age at diagnosis significantly increased during the study period, whereas growth hormone and insulin-like growth factor I decreased. Incidentalomas constituted 32% of all cases diagnosed with acromegaly in the last decade. Primary surgery was used in 93% of all cases, and repeated surgery decreased from 24% to 10% during the three decades. The use of first-generation somatostatin analogues (21%-48%) and second-line medical treatment (4%-20%) increased with a concomitant improvement of biochemical disease control (58%-91%).

CONCLUSION

The prevalence of acromegaly is higher than previously reported and the clinical presentation has shifted towards a milder phenotype. Modern treatment of acromegaly enables individualized treatment and disease control in the majority of patients.

Mean GH profile is more accurate than single fasting GH in the evaluation of acromegaly disease control during somatostatin receptor ligands therapy

PURPOSE

This study aims to compare the accuracy of mean GH profile (GHP) < 2.5 ng/ml and single fasting GH (SGH) < 1 ng/ml in the evaluation of disease control in acromegaly patients during somatostatin receptor ligands (SRLs) therapy.

METHODS

We retrospectively enrolled 100 acromegaly patients, 68 responder, and 32 partial responder to SRLs. Controlled disease has been defined as IGF-I levels within age-related normal limits, while partial response as pathological IGF-I values despite a reduction ≥ 50%. In all patients, GHP, SGH, IGF-I, and IGFBP-3 were evaluated.

RESULTS

Median GHP levels (1.2 ng/ml, IQR 0.5-2.3 ng/ml) were lower (p = 0.001) than SGH (1.9 ng/ml, IQR 1.0-3.6 ng/ml). Accuracy of GHP was 81%, whereas that of SGH was 55%, with a Kappa index of 0.520 and 0.237, respectively. In multivariable analysis GHP (p = 0.002) and IGFBP-3 (p = 0.004), but not SGH, were independently associated with normal IGF-I levels. At receiver-operator characteristic curve (ROC) analysis GHP cut-off sensitivity and specificity were 94.1% and 50.0%, respectively, while SGH sensitivity and specificity were 35.3% and 93.7%, respectively. Finally, in obese patients the GH cut-off level (both as SGH and GHP) associated to good disease control was significantly different with respect to not obese ones.

CONCLUSIONS

GHP associates with IGF-I (and therefore with appropriate control of disease) with higher accuracy than SGH. When GH evaluation is needed, the measurement of mean GHP should be preferred and use of BMI-related cut-offs is suggested.

Biochemical discrepancies in the evaluation of the somatotroph axis: Elevated GH or IGF-1 levels do not always diagnose acromegaly

The most frequent diagnosis underlying the finding of an elevated growth hormone (GH) and insulin-like growth factor-1 (IGF-1) is acromegaly due to a GH-secreting pituitary tumour. However, GH and IGF-1 levels can be discordant in patients with acromegaly due to early or partially treated disease, or there might be another cause of high GH or high IGF-1 unrelated to acromegaly, such as pre-analytical and technical pitfalls, physiological circumstances and pathological conditions. High GH and normal or low serum IGF-1, or alternatively, normal GH with elevated serum IGF-1, should be carefully assessed to avoid misinterpreting the activity of acromegaly or misdiagnosing a patient with acromegaly. We summarise here these biochemical discrepancies in the evaluation of the somatotroph axis.

[Discordant parameters of insulin-like growth factor 1 and growth hormone in the diagnosis and monitoring of acromegaly]

Acromegaly is a rare endocrine disorder associated with multiple complications and increased mortality. Timely diagnosis and adequate treatment can bring the life expectancy of patients with acromegaly closer to the general population level. The tests for the diagnosis of acromegaly are measurement of both serum GH, and GH after oral glucose administration; serum insulin-like growth factor-1 (IGF-1). However, in clinical practice, up to 39% of patients with discordant results are found. The patients with discordant GH and IGF-1levels, are the most difficult to manage. This review discusses the prevalence of discordant GH and IGF-1 outcomes in patients with acromegaly; factors causing this discrepancy; the impact of hormone levels on treatment outcomes. Although endocrinologists are used to dealing with this discrepancy in clinical practice for many years, discordant patients'outcome remains uncertain and undefined The optimal treatment should be individually tailored for each patient, taking into account all clinical parameters.

GH and IGF-I levels and tumor shrinkage in response to first generation somatostatin receptor ligands in acromegaly: a comparative study between two reference centers for pituitary diseases in Brazil

PURPOSE

To compare biochemical and tumor response rates between two reference centers for pituitary diseases in Brazil after primary and adjuvant therapy with somatostatin receptor ligands (SRL) in acromegaly.

METHODS

Patients were classified as non-responders (NR), partial responders (PR), and full responders (FR) to 12-month SRL therapy according to: [criteria A] normal IGF-I and random GH (rGH) < 1 ng/mL (FR); ≥ 50% decrease of IGF-I and/or rGH (PR); < 50% decrease of IGF-I and rGH (NR); [criteria B] normal IGF-I (FR); ≥ 50% decrease of IGF-I (PR); < 50% decrease of IGF-I (NR). Tumor shrinkage <20% defined poor responders (tPR) and ≥ 20% good responders (tGR).

RESULTS

We studied 219 acromegaly patients (59% women, age 43.1 ± 13.9 years; 73 from Center I and 146 from Center II). After SRL therapy, the proportion of FR, PR, and NR by criteria A and B was 30.2 vs 49.1%, 52.8 vs 21.2% and 17 vs 29.7%, respectively (p < 0.001). Considering criteria A or B separately, there was no difference in the proportion of FR, PR and NR between two centers. However, when comparing criteria A and B, the Center I showed a difference of 30.9% in classification of FR in relation to 13.2% observed in Center II (p = 0.006). tGR were 51.4% of patients, with no differences between the centers.

CONCLUSIONS

IGF-I alone significantly increased positive response rates to SRLs, whereas the inclusion of rGH levels into therapeutic decision might lead to a significant increment on the costs of acromegaly management.

Value of Early Post-Operative Growth Hormone Testing in Predicting Long-Term Remission and Residual Disease after Transsphenoidal Surgery for Acromegaly

INTRODUCTION

Surgical remission for acromegaly is dependent on a number of factors including tumour size, invasiveness, and surgical expertise. We studied the value of early post-operative growth hormone (GH) level as a predictor of outcome and to guide early surgical re-exploration for residual disease in patients with acromegaly.

METHODS

Patients with acromegaly undergoing first-time endoscopic transsphenoidal surgery between 2005 and 2015, in 2 regional neurosurgical centres, were studied. Insulin-like growth factor-1 (IGF-1), basal GH (i.e., sample before oral glucose), and GH nadir on oral glucose tolerance test (OGTT) were tested at various time points, including 2-5 days post-operatively. Definition of disease remission was according to the 2010 consensus statement (i.e., GH nadir <0.4 μg/L during an OGTT and normalized population-matched IGF-1). Forward stepwise logistic regression was used to determine factors associated with remission.

RESULTS

We investigated 81 consecutive patients with acromegaly, 67 (83%) of which had macroadenomas and 22 (27%) were noted to be invasive at surgery. Mean follow-up was 44 ± 25 months. Overall, surgical remission was achieved in 55 (68%) patients at final follow-up. On univariate analysis, the remission rates at the end of the study period for patients with early post-operative GH nadir on OGTT of <0.4 (N = 43), between 0.4 and 1 (N = 28), and >1 μg/L (N = 8) were 88, 54, and 20%, respectively. Similar results were seen with basal GH on early post-operative OGTT. On multivariate regression analysis, pre-operative IGF-1 (odds ratio of 13.1) and early post-operative basal GH (odds ratio of 5.0) and GH nadir on OGTT (odds ratio of 6.8) were significant predictors of residual disease. Based on a raised early GH nadir and post-operative MR findings, 10 patients underwent early surgical re-exploration. There was reduction in post-operative GH levels in 9 cases, of which 5 (50%) achieved long-term remission. There was an increased risk of new pituitary hormone deficiencies in patients having surgical re-exploration compared to those having a single operation (60 vs. 14%).

CONCLUSIONS

An early post-operative basal GH and GH nadir on OGTT are reliable predictors of long-term disease remission. It can be used to guide patients for early surgical re-exploration for residual disease, although there is increased risk of hypopituitarism.

Discordant GH and IGF-1 Results in Treated Acromegaly: Impact of GH Cutoffs and Mean Values Assessment

CONTEXT

Discordant growth hormone (GH) and insulin-like growth factor-1 (IGF-1) values are frequent in acromegaly.

OBJECTIVE

To evaluate the impact of different GH cutoffs on discordance rate. To investigate whether the mean of consecutive GH measurements impacts discordance rate when matched to the last available IGF-1 value.

DESIGN

Retrospective study.

SETTING

Referral center for pituitary diseases.

PATIENTS

Ninety acromegaly patients with at least 3 consecutive evaluations for GH and IGF-1 using the same assay in the same laboratory (median follow-up 13 years).

INTERVENTIONS

Multimodal treatment of acromegaly.

MAIN OUTCOME MEASURES

Single fasting GH (GHf) and IGF-1 (IGF-1f). Mean of 3 GH measurements (GHm), collected during consecutive routine patients' evaluations.

RESULTS

At last evaluation GHf values were 1.99 ± 2.79 µg/L and age-adjusted IGF-1f was 0.86 ± 0.44 × upper limit of normality (mean ± SD). The discordance rate using GHf was 52.2% (cutoff 1 µg/L) and 35.6% (cutoff 2.5 µg/L) (P = 0.025). "High GH" discordance was more common for GHf <1.0 µg/L, while "high IGF-1" was predominant for GHf <2.5 µg/L (P < 0.0001). Using GHm mitigated the impact of GH cutoffs on discordance (GHm <1.0 µg/L: 43.3%; GHm <2.5 µg/L: 38.9%; P = 0.265). At receiver-operator characteristic curve (ROC) analysis, both GHf and GHm were poor predictors of IGF-1f normalization (area under the curve [AUC] = 0.611 and AUC = 0.645, respectively). The prevalence of disease-related comorbidities did not significantly differ between controlled, discordant, and active disease patients.

DISCUSSION

GH/IGF-1 discordance strongly depends on GH cutoffs. The use of GHm lessen the impact of GH cutoffs. Measurement of fasting GH levels (both GHf and GHm) is a poor predictor of IGF-1f normalization in our cohort.

Discordant biological parameters of remission in acromegaly do not increase the risk of hypertension or diabetes: a study with the Liege Acromegaly Survey database

PURPOSE

Acromegaly is a rare disease due to growth hormone (GH)-secreting pituitary adenoma. GH and IGF-1 levels are usually congruent, indicating either remission or active disease; however, a discrepancy between GH and IGF-1 may occur. We aimed to evaluate the outcome of diabetes mellitus (DM) and hypertension (HT) in acromegalic patients with congruent GH and/or IGF-1 levels vs. discordant biochemical parameters.

METHODS

Retrospective analysis of the data of 3173 patients from the Liege Acromegaly Survey (LAS) allowed us to include 190 patients from 8 tertiary referral centers across Europe, treated by surgery, with available data concerning DM and HT both at diagnosis and at the last follow-up (LFU). We recorded the number of anti-HT and anti-DM drugs used at the first evaluation and at LFU for every patient.

RESULTS

Ninety-nine patients belonged to the REM group (concordant parameters), 65 patients were considered as GH_dis (high random GH/controlled IGF-1), and 26 patients were considered as IGF-1_dis (high IGF-1/controlled random GH). At diagnosis, 72 patients (37.8%) had HT and 54 patients had DM (28.4%). There was no statistically significant difference in terms of the number of anti-HT and anti-DM drugs at diagnosis versus LFU (mean duration: 7.3 ± 4.5 years) between all three groups.

CONCLUSION

The long-term outcome of DM and HT in acromegaly does not tend to be more severe in patients with biochemical discordance in comparison with patients considered as in remission on the basis of concordant biological parameters, suggesting that patients with biochemical discordance do not require a closer follow-up.

Biochemical Control in Acromegaly With Multimodality Therapies: Outcomes From a Pituitary Center and Changes Over Time

PURPOSE

To determine the prevalence of insulin-like growth factor-1 (IGF-1) normalization with long-term multimodality therapy in a pituitary center and to assess changes over time.

METHODS

Patients with acromegaly (N = 409), with ≥1 year of data after surgery and at least 2 subsequent clinic visits were included in long-term analysis (N = 266). Biochemical data, clinical characteristics, and therapeutic interventions were reviewed retrospectively.

RESULTS

At diagnosis, mean [standard deviation] age was 43.4 [14.3] years, body mass index was 28.5 (24.9-32.1) kg/m2 (median, interquartile range), serum IGF-1 index (IGF-1 level/upper limit of normal) was 2.3 [1.7-3.1], and 80.5% had macroadenomas. Patients with transsphenoidal surgery after 2006 were older [46.6 ± 14.3 vs 40.0 ± 13.4 years; P < 0.001]. Age and tumor size correlated inversely. Overall (N = 266), 93.2% achieved a normal IGF-1 level during 9.9 [5.0-15.0] years with multimodality therapy. The interval to first normal IGF-1 level following failed surgical remission was shorter after 2006: 14.0 (95% confidence interval, 10.0-20.0) versus 27.5 (22.0-36.0) months (P = 0.002). Radiation therapy and second surgery were rarer after 2006: 28 (22%) versus 62 (47.0%); P < 0.001 and 12 (9.4%) versus 28 (21.2%); P = 0.010, respectively. Age at diagnosis increased over time periods, possibly reflecting increased detection of acromegaly in older patients with milder disease. Male gender, older age, smaller tumor and lower IGF-1 index at diagnosis predicted long-term sustained IGF-1 control after surgery without adjuvant therapies.

CONCLUSION

The vast majority of patients with acromegaly can be biochemically controlled with multimodality therapy in the current era. Radiotherapy and repeat pituitary surgery became less frequently utilized over time. Long-term postoperative IGF-1 control without use of adjuvant therapies has improved.

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.

[Not Available]

Acromegaly is characterized by increased release of growth hormone (GH) and, consequently, Insulin-Like Growth Factor I (IGF-I), most often by a pituitary adenoma. Prolonged exposure to excess hormone leads to progressive somatic disfigurement and a wide range of systemic manifestations that are associated with increased mortality. Transsphenoidal adenomectomy is the treatment of choice of GH-secreting pituitary tumors but surgical cure is not achieved in around 50% of patients, then adjuvant treatment is necessary. Mortality in acromegaly is normalized with biochemical control and has decreased in the last decade with the increased use of adjuvant therapy. Both GH and IGF-I are currently biomarkers for assessing disease activity in patients with acromegaly. However, discordance between GH and IGF-I results is encountered in a quarter of treated patients. The impacts of such a discrepancy over mortality and morbidity and the risk of biochemical and/or clinical recurrence are unclear. Moreover, despite a good biochemical control, some symptoms persist, leading to a decreased quality of life. Back pain due to vertebral fractures seem to be frequent in these patients and underdiagnosed. In patients with acromegaly, bone mineral density is not a reliable predictor of fracture risk. A more accurate evaluation of bone microstructural alterations associated with GH hypersecretion and vertebral fractures may be provided by new radiological devices analyzing alteration of trabecular microarchitecture, leading to a better prevention. © 2019 Published by Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Les Must de l'Endocrinologie 2019 réalisé avec le soutien institutionnel de Ipsen-Pharma.

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.

Targeting either GH or IGF-I during somatostatin analogue treatment in patients with acromegaly: a randomized multicentre study

CONTEXT

Discordant GH and IGF-I values are frequent in acromegaly. The clinical significance and its dependence on treatment modality and of glucose-suppressed GH (GH_nadir) measurements remain uncertain.

OBJECTIVE

To evaluate the effects of targeting either IGF-I or GH during somatostatin analogue (SA) treatment.

PATIENTS AND METHODS

84 patients with controlled acromegaly after surgery (n = 23) or SA (n = 61) underwent a GH profile including an OGTT, at baseline and after 12 months. SA patients were randomized to monitoring according to either IGF-I (n = 33) or GH_nadir (n = 28). SA dose escalation was allowed at baseline and 6 months.

MAIN OUTCOME MEASURES

GH_nadir and IGF-I at baseline and 12 months, and disease-specific Quality of Life (QoL).

RESULTS

IGF-I and fasting GH levels were comparable between the surgery and the SA group, whereas GH_nadir (µg/L) was lower in the surgery group (GH_nadir 0.7 ± 0.1 vs 0.3 ± 0.1, P < 0.01). SA dose increase was performed in 20 patients in the GH group and in 8 patients in the IGF-I group (P = 0.02), which increased the number of concordantly controlled patients (P = 0.01). QoL was only mildly affected at baseline in all groups and did not changed consistently during the study.

CONCLUSION

(1) Discordant values in terms of high GH levels are prevalent in SA patients and more so if applying glucose-suppressed GH_nadir; (2) targeting discordant levels of either GH or IGF-I translates into SA dose increase and improved biochemical control; (3) even though QoL was not improved in this study, we suggest biochemical assessment of disease activity to include glucose-suppressed GH_nadir also in SA patients.

Twenty-four-hour growth hormone profiling in the assessment of acromegaly

OBJECTIVES AND BACKGROUND

Recent guidelines recommend insulin-like growth factor (IGF-1), random growth hormone (GH) and nadir GH on an oral glucose tolerance test (OGTT) for assessment of acromegaly. At this Regional Centre, the 24-hour GH profile has also been used.

DESIGN PATIENTS AND MEASUREMENTS

We evaluated 57 GH profiles from 34 patients from 2008 to 2012. Samples were drawn every 2 hour and matched with 0800 GH, nadir GH after OGTT and IGF-1.

RESULTS

Correlations between the mean 13-point profiles and mean 5-point profile, OGTT nadir and 0800 GH were as follows: r = .99, .99 and .90, respectively (P < .01 for all). The correlation between the mean 13-point profiles and IGF-1 was r = .32 P = .02.Of 5 patients with very high 0800 GH preoperatively (≥20 μg/L), mean 13-point GH reduced by 88%-99% postoperatively. IGF-1 did not normalize in these patients, and all required extra treatment. Preoperatively, all patients had concordant 0800 GH and IGF-1. Postoperatively, 6 patients had 0800 GH <1 μg/L and high IGF-1; only 2 of these had a 13-point mean >1 μg/L, but 5 required further treatment.

CONCLUSIONS

Growth hormone profiling is not necessary for assessing the majority of patients with acromegaly if there is confidence in the local IGF-1 assay. When undertaken, a 5-point profile is adequate. In patients with very high 0800 GH, 24-hour profiling was useful in demonstrating partial therapeutic success but did not alter management. Further work is needed to explore the possible role of GH profiling in stratifying patients with discordant IGF-1 and GH results.

The impact of adjustments to the diagnostic criteria for biochemical remission in surgically treated patients with acromegaly

BACKGROUND

The suggested criteria for biochemical remission in patients treated for acromegaly were recently modified. The aim of this project was to study to what extent this modification influences remission rates.

DESIGN, PATIENTS AND METHODS

This was a retrospective study of 55 consecutive patients [29 men; median age 47years (interquartile range 38-68)] diagnosed with acromegaly between 2003 and 2014. After treatment serum IGF-I and/or GH was measured according to a standardized protocol. The biochemical remission status was defined according to the clinical guidelines from 2010 and2014.

RESULTS

Out of 55 patients, 44 patients were primarily operated. Of these, 33 (75%) were evaluated 3-12months postoperatively by measuring serum IGF-I and GH during an oral glucose tolerance test. According to the 2010 guidelines, 11 patients (33%) were in biochemical remission, 15 patients (46%) were not and 7 patients (21%) had discordant results (normal IGF-I and high GH or vice versa). Applying the 2014 guidelines in the same group, 16 patients (49%) were in biochemical remission, 7 patients (21%) were not and 10 patients (30%) had discordant results. Thus, by using the most recent criteria for biochemical control, more patients were considered to be in remission, or with discordant results, and fewer patients not in remission (P<0.05).

CONCLUSION

An apparently minor adjustment of the criteria for biochemical control has a significant impact on remission status in patients treated for acromegaly, eventually affecting follow-up and treatment strategies.

Matrix metalloproteinase 2 (MMP-2) levels are increased in active acromegaly patients

PURPOSE

During follow-up of acromegaly patients, there is a discordance rate of 30% between the measurements of growth hormone and insulin-like growth factor-1 levels. Further tests are required to determine disease activity in patients with discordant results. This study was planned to investigate an association of serum levels of matrix metalloproteinase-2, matrix metalloproteinase-9, and cathepsin B with disease activity in acromegaly patients.

METHODS

In this study, 64 acromegaly patients followed in our clinic were divided into two groups according to the 2010 consensus criteria for cure of acromegaly as patients with active disease (n = 24) and patients with controlled disease (n = 40). Serum matrix metalloproteinase-2, matrix metalloproteinase-9, and cathepsin B levels were measured by the enzyme-linked immunosorbent assay method.

RESULTS

The mean serum matrix metalloproteinase-2 level was significantly higher in the active acromegaly patients than in the controlled acromegaly patients (150.1 ± 54.5 ng/mL vs. 100.2 ± 44.6 ng/mL; p < 0.0001). There was no significant difference between the active and controlled acromegaly patients regarding serum matrix metalloproteinase-9 and cathepsin B levels (p = 0.205 and p = 0.598, respectively). Serum matrix metalloproteinase-2 levels of 118.3 ng/mL and higher had a sensitivity of 75% and a specificity of 77.5% in determining active disease. The risk of active acromegaly was 3.3 fold higher in the patients with a matrix metalloproteinase-2 level of >118.3 ng/mL than in the patients with a matrix metalloproteinase-2 level of <118.3 ng/mL.

CONCLUSIONS

In this study, serum matrix metalloproteinase-2 level is increased in the active acromegaly patients and a threshold value in determining active disease was defined for serum matrix metalloproteinase-2 level. This study is the first to compare acromegaly patients having active or controlled disease in terms of matrix metalloproteinase-2 and matrix metalloproteinase-9 levels. The results need to be confirmed by a study that will be conducted in a larger patient group also including a healthy control group to demonstrate the value of this novel marker in disease activity.

Long-term outcomes of acromegaly treated with fractionated stereotactic radiation: case series and literature review

Background

Growth hormone (GH)-secreting pituitary adenomas represent an uncommon subset of pituitary neoplasms. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) have been used as primary or adjuvant treatment. The purpose of this study is to report the long-term tumor control and toxicity from our institution and to perform a systematic literature review of acromegaly patients treated with FSRT.

Methods

We retrospectively reviewed all patients treated with FSRT (median dose 50.4 Gray [Gy], range 50.4-54 Gy) between 2005 and 2012 who had: 1) GH-secreting adenoma with persistently elevated insulin growth factor-1 (IGF-1) despite medical therapy and 2) clinical follow up >3 years after FSRT. Patients were treated with modern FSRT planning techniques. Biochemical control was defined as IGF-1 normalization. Systematic review of the literature was performed for FSRT in acromegaly.

Results

With a median follow-up of 80 months, radiographic control was achieved in all 11 patients and overall survival was 100%. Long-term biochemical control was achieved in 10 patients (90.9%) with either FSRT alone (36.4%) or FSRT with continued medical management (45.5%). No patient experienced new hypopituitarism, cranial nerve dysfunctions, or visual deficits. Our systematic review found published rates of biochemical control and hypopituitarism vary, with uniformly good radiographic control and low incidence of visual changes.

Conclusions

Adjuvant FSRT offered effective long-term biochemical control and radiographic control, and there was a lower rate of complications in this current series. Review of the literature shows variations in published rates of biochemical control after FSRT for acromegaly, but low incidence of serious toxicities.