Monitoring of acromegaly: what should be performed when GH and IGF-1 levels are discrepant?

Reevaluation of Acromegalic Patients in Long-Term Remission according to Newly Proposed Consensus Criteria for Control of Disease

Acromegaly guidelines updated in 2010 revisited criteria of disease control: if applied, it is likely that a percentage of patients previously considered as cured might present postglucose GH nadir levels not adequately suppressed, with potential implications on management. This study explored GH secretion, as well as hormonal, clinical, neuroradiological, metabolic, and comorbid profile in a cohort of 40 acromegalic patients considered cured on the basis of the previous guidelines after a mean follow-up period of 17.2 years from remission, in order to assess the impact of the current criteria. At the last follow-up visit, in the presence of normal IGF-I concentrations, postglucose GH nadir was over 0.4 μg/L in 11 patients (Group A) and below 0.4 μg/L in 29 patients (Group B); moreover, Group A showed higher basal GH levels than Group B, whereas a significant decline of both GH and postglucose GH nadir levels during the follow-up was observed in Group B only. No differences in other evaluated parameters were found. These results seem to suggest that acromegalic patients considered cured on the basis of previous guidelines do not need a more intensive monitoring than patients who met the current criteria of disease control, supporting instead that the cut-off of 0.4 mcg/L might be too low for the currently used GH assay.

[Drug therapy for acromegaly]

Prolonged overproduction of growth hormone, like insulin-like growth factor-1 hypersecretion leads to acromegaly in adults. This is associated with several co-morbidities and increased mortality. Despite typical clinical features and modern diagnostic tools, it often takes years to diagnose from the onset of the disease. The aims of the treatment are to reduce or control tumour growth, inhibit growth hormone hypersecretion, normalize insulin-like growth factor-1 levels, treat co-morbidities and, therefore, reduce mortality. There are three approaches for therapy: surgery, medical management (dopamine agonists, somatostatin analogues and growth hormone receptor antagonist), and radiotherapy. Efficient therapy of the disease is based on the appropriate multidisciplinary team management. The review provides a summary of medical treatment for acromegaly.

Monitoring for potential residual disease activity by serum insulin-like growth factor 1 and soluble Klotho in patients with acromegaly after pituitary surgery: is there an impact of the genomic deletion of exon 3 in the growth hormone receptor (d3-GHR) gene on "safe" GH cut-off values?

BACKGROUND

Acromegaly is an illness usually defined by excessively high growth hormone (GH) and insulin like growth factor 1 (IGF-1) levels, the latter mainly reflecting GH action on the liver. IGF-1, also known as somatomedin C, mediates several actions of GH. The diagnosis and management of acromegaly is relatively straight forward, but long-term follow-up of patients can be difficult, as elevated IGF-1 levels can occur in the presence of apparently normalised GH levels and late recurrence of acromegaly may arise despite previous suppression on oral glucose tolerance testing. Data suggest this applies especially to patients in whom the GH receptor lacks exon 3. In such patients, GH may not always be a useful marker of disease, and traditional GH cut-offs may be misleading. Recent data suggest that soluble Klotho (sKlotho), besides and in addition to IGF-1, may help monitor the activity of GH-producing adenomas (presumably reflecting GH action on the kidneys) and may be a useful supplementary tool.

METHODS

GHR genotyping was performed in 112 patients with acromegaly. IGF-1 and sKlotho levels were measured in the sera of patients before and after transsphenoidal surgery, with emphasis on patients judged inconclusively cured by surgery or with small residual tumour masses shortly after surgery. Patients were assessed for recurrence of acromegaly with GH levels (random or nadir during an oGTT).

RESULTS

Of the 48 patients who underwent surgery between 2000 and 2009 and who had well-documented longer term follow-up at our institution, 29 had no biochemical evidence of residual disease activity after transsphenoidal surgery (marked reduction in IGF-1 and sKlotho levels, GH suppressible to <1 ng/ml) and were classified as in remission. 2 of these patients developed recurrent symptoms of acromegaly during follow-up with increasing levels of IGF-1 and sKlotho, and both patients were carriers of the d3-GHR genotype.

CONCLUSIONS

Acromegalic patients with the d3-GHR polymorphism might be - for a given low postsurgical GH level - at higher risk for recurrence and may require a lower GH nadir during oGTT to be classified as in remission. Soluble Klotho could be useful in the follow-up of acromegalic patients. The question arises whether sKlotho not only reflects the activity of GH-secreting pituitary adenomas but whether Klotho (ectodomain clipping?) could also mediate selected actions of GH.

Insulin-like growth factor-I correlates more closely than growth hormone with insulin resistance and glucose intolerance in patients with acromegaly

In normal subjects growth hormone (GH) and insulin-like growth factor-I (IGF-I) have opposing effects on glucose metabolism. Active acromegaly is associated with insulin resistance (IR) and glucose intolerance although both GH and IGF-I are elevated. Our objective was to compare whether GH or IGF-I correlates more closely with IR and glucose intolerance in acromegaly. Basal serum IGF-I and GH, glucose and insulin during an oral glucose tolerance test were measured in 70 normoglycemic and 44 hyperglycemic acromegalic patients (21 impaired fasting glucose, 11 impaired glucose tolerance and 12 diabetes mellitus) according to American Diabetes Association criteria. 55 patients were assessed before any treatment for acromegaly and 59 after surgery and/or radiotherapy (15 patients had normal IGF-I after treatment). Patients treated with somatostatin analogs, GH-receptor antagonists or antidiabetic drugs were excluded. IR was assessed by various basal and stimulated indices. Homeostatic Model Assessment 2-Insulin Resistance (HOMA2-IR) index correlated more closely with IGF-I (r = 0.65, p < 0.0001) than nadir (r = 0.23, p = 0.008) or random GH (r = 0.26, p = 0.002). HOMA2-IR correlated better with IGF-I than nadir or random GH also in normoglycemic (n = 70; r = 0.74, p < 0.0001 vs. r = 0.36, p = 0.001 vs. r = 0.39, p < 0.001) and hyperglycemic patients (n = 44; r = 0.54, p = 0.0002 vs. r = 0.09, p = 0.4 vs. r = 0.14, p = 0.26). In multivariate logistic regression analysis IGF-I but not GH was a significant risk factor for glucose intolerance after adjusting for age, sex, weight and acromegaly duration (OR = 1.56, p = 0.01). In acromegaly IGF-I correlates more closely than GH with IR. IGF-I levels but not GH are associated with glucose intolerance.

Nationwide survey of acromegaly in South Korea

CONTEXT

It was previously reported in Korea that there were 1.4 case per million per year of acromegaly. This was low in comparison with the extrapolated values of Western European countries. We expected that the incidence of acromegaly would be much higher now because of recently improved medical facilities, diagnostic tools and coverage of medical insurance to all the population of South Korea.

OBJECTIVE

The purpose of this nationwide survey was to examine the incidence and prevalence of patients with acromegaly, mode of treatment and outcome of surgical treatment of recent 5 years.

DESIGN AND PATIENTS

We requested and collected the medical records of all possible patients with acromegaly from 74 secondary or tertiary medical institutes in Korea from 2003 to 2007 retrospectively.

MEASUREMENTS

Date of diagnosis and treatment, tumour size, pre- and postoperative hormonal level, treatment modality and usage of medication were collected.

RESULTS

During 5 years, 1350 patients with acromegaly had been registered. The average annual incidence was 3.9 cases per million during this period, and prevalence had increased up to 27.9 cases per million in 2007. Male/female ratio was 1:1.2, and mean age at diagnosis was 44.1 years. Macroadenoma was dominant (82.9%). Transsphenoidal adenoidectomy was used the most as primary treatment (90.4%).

CONCLUSIONS

This Korean acromegaly survey offers a realistic overview of the predominant epidemiological characteristics of acromegaly in Korea. Annual incidence was at a similar level with western countries. Efforts to diagnose and control the disease earlier are recommended.

Outcome of multimodal therapy in operated acromegalic patients, a study in 115 patients

INTRODUCTION

Given the new therapeutic options in acromegaly, it seemed important to evaluate the outcome of operated acromegalic patients today.

OBJECTIVE

To analyse the characteristics and short- and long-term surgical outcome of patients who underwent transsphenoidal surgery for a growth hormone (GH)-secreting adenoma in our centre and to determine predictive factors of remission.

DESIGN AND PATIENTS

This retrospective 10-year study included 115 newly diagnosed acromegalic patients operated on at Timone University Hospital, Marseille, France, between 1997 and 2007.

MEASUREMENTS

Initial and long-term outcomes were evaluated using stringent and current remission criteria, associating GH nadir after oral glucose tolerance test <0·4 μg/l and normal insulin-like growth factor-1 (IGF-1) at 3 months, and a normal IGF-1 at the end of follow-up (52·4 ± 36·8 months, median 41 months, range 6·7-135·4 months, n = 99).

RESULTS

At the end of follow-up, 90·9% of patients had controlled disease. Overall, 49·5% of patients were in long-term remission after surgery alone, and only 2·0% of patients experienced recurrent disease. Multivariate predictors of 3-month remission included mean GH at diagnosis (P = 0·033), tumour invasion (P = 0·013) and surgeon report of incomplete or uncertain macroscopic resection (P = 0·003 and P = 0·047, respectively). Multivariate predictors at diagnosis of long-term remission included mean GH level (P = 0·048), adenoma size (P = 0·007) and absence of pituitary deficit (P = 0·026).

CONCLUSIONS

In long-term follow-up after surgery of acromegaly, half of the patients achieved remission after surgery alone and more than 90% had their disease controlled. With stringent 3-month remission criteria, recurrence was rare.

Long-term outcome in patients with acromegaly: analysis of 1344 patients from the German Acromegaly Register

BACKGROUND

Acromegaly is a rare disease with significant morbidity and increased mortality. Epidemiological data about therapeutic outcome under 'real life' conditions are scarce.

OBJECTIVE

To describe biochemical long-term outcome of acromegaly patients in Germany.

DESIGN AND METHODS

Retrospective data analysis from 1344 patients followed in 42 centers of the German Acromegaly Register. Patients' data were collected 8.6 (range 0-52.6) years after diagnosis. Controlled disease was defined by an IGF1 within the center-specific reference range.

RESULTS

Nine hundred and seventeen patients showed a normalized IGF1 (157 (range 25-443) ng/ml). In patients with a diagnosis dated back >2 years (n=1013), IGF1 was normalized in 76.9%. Of the patients, 19.5% had an elevated IGF1 and a random GH ≥1 ng/ml, 89% of the patients had at least one surgical intervention, 22% underwent radiotherapy, and 43% received medical treatment. After surgery 38.8% of the patients were controlled without any further therapy. The control rates were higher in surgical centers with a higher caseload (P=0.034). Of the patients with adjunctive radiotherapy 34.8% had a normal IGF1 8.86 (0-44.9) years post irradiation, 65.2% of the medically treated patients were controlled, and 47.2% of the patients with an elevated IGF1 received no medical therapy.

CONCLUSION

The majority of acromegaly patients were controlled according to their IGF1 status. Long-term outcome could be improved by exploiting medical treatment options especially in patients who are not controlled by surgery and/or radiotherapy.

Comparison of two immunoassays in the determination of IGF-I levels and its correlation with oral glucose tolerance test (OGTT) and with clinical symptoms in acromegalic patients

The aim of our study was to evaluate two different methodologies in IGF-I levels determination, its correlation with GH nadir in OGTT <1 and <0.4 ng/ml and with clinical symptoms in acromegalic patients. We analyzed 37 patients. Sixteen patients had not undergone any kind of treatment (Group 1). Twenty-one patients underwent surgery as primary treatment, and after that, some of them another kind of treatment (except pegvisomant) (Group 2). Serum IGF-I levels were measured by Immulite-1000 (IMM) and by an immunoradiometric assay (DSL) and, GH by immunochemiluminometric assay. IGF-I levels by IMM and by DSL showed a significant difference. When we analyzed in both groups the concordance by crosstabs-Kappa coefficients, between different parameters, GH nadir <1 and <0.4 ng/ml with IGF-I by DSL and IMM showed concordance in group 1, but in group 2 only GH nadir <1 and <0.4 ng/ml had a weak concordance with IGF-I by IMM. When we analyzed clinical symptoms in the patients and, GH nadir <1 and <0.4 ng/ml and IGF-I levels by both methodologies, more than 90% of clinically active patients had abnormal GH response or/and elevated IGF-I levels in group 1, but less than 70% in group 2. In the 8 patients under medical treatment, GH nadir was higher than 0.4 ng/ml in all patients, and IGF-I levels were elevated in 8/8 by DSL and in 6/8 by IMM. In conclusion, discrepant GH and IGF-I levels in the diagnosis and follow-up of patients with acromegaly requires consideration of many factors that influence these parameters.

Discordant growth hormone and IGF-1 levels post pituitary surgery in patients with acromegaly naïve to medical therapy and radiation: what to follow, GH or IGF-1 values?

New criteria that define acromegaly remission are more stringent: normal (age/sex-adjusted) insulin-like growth factor type 1 (IGF-1), growth hormone (GH) random (GHr) <1 μg/L, and a GH nadir (GHn) during oral glucose tolerance test (OGTT) of <0.4 μg/L. Discordance between GH and IGF-1 values is often attributed to somatostatin receptor ligands (SRLs) or radiation. The purpose of this study was to evaluate rates of discordant IGF-1 and GH levels in patients with GH secreting adenomas (after pituitary surgery), who were naïve to any other treatment. We retrospectively analyzed data over a 5 year time period (2006-2010), in post-surgery acromegaly patients who had elevated IGF-1 but normal GH levels (per the new cure criteria). Symptoms of acromegaly were scored according to a 4-point scale. Fifty-four patients had post-operative GHr and IGF-1 measurements, 28 patients had GHn during OGTT, and 16 patients had 5-point 2-h GH day curve tests. Thirteen of 54 (24%) patients were found to have intermittent persistent discordant values; high IGF-1 and normal GH at final evaluation (77% of these patients were women). Patients had a median number of IGF-1 evaluations of 7.5 (range: 2-15) over a median of 22 months (range: 3-47 months). Mean elevated IGF-1 in the discordant population was 1.25 × upper limit of normal (ULN) ± 0.17 (range: 1.01-1.6 × ULN). Twelve of the 13 (92%) patients had macroadenomas; 10 of the 13 (69%) patients had mammosomatotroph, mixed lacto/somatotroph tumors or prolactin staining. No patient in the discordant population was on estrogen replacement therapy or had overt cardiac disease. When the relatively asymptomatic discordant population was compared with 35 patients from the concordant population (six were excluded because of preoperative medical treatment for acromegaly), no significant difference between age, gender distribution, body mass index (BMI), presence of diabetes mellitus (DM) or glucose intolerance and adrenal insufficiency between groups was noted. In our study of postoperative patients with acromegaly naïve to both SRLs and radiation, using new GH cut-off levels, 24% had intermittent or persistent discordant values. Our results highlight that relying on IGF-1 or GH measurements alone is not adequate for assessing disease control in surgically treated acromegaly patients. Management of such patients needs to be individualized and long-term studies evaluating morbidity and mortality incorporated into treatment decisions. Further studies with larger patient populations and longer follow-up are required to determine the long-term implications of discordant GH and IGF-1 value patterns.

Screening for acromegaly by application of a simple questionnaire evaluating the enlargement of extremities in adult patients seen at primary health care units

The objective of this study was to screen for acromegaly by application of a simple questionnaire in patients seen at primary health care units. A total of 17,000 patients of both genders >18 and <70 years seen by general practitioner were interviewed. Patients with known pituitary disease and pregnant women were excluded. A simple questionnaire was applied to the patients: Has your shoe size increased over the last 5 years? Did you have to change your wedding ring or ring over the last 5 years because it became tight? In one patient, the diagnosis of acromegaly was suspected by the physician. Among the remaining patients, 178 (1%) responded positively to one of the items of the questionnaire and were submitted to IGF-1 measurement. Five patients had persistently elevated IGF-1 and inadequate suppression of GH in the OGTT (without other conditions associated with GH or IGF-1 elevation). One of these patients presented a normal pituitary upon magnetic resonance imaging and adenoma was detected in the other four; two presented the typical facies and two others reported changes in physiognomy (confirmed by the comparison of photographs), in addition to the enlargement of extremities. The present investigation suggests a much higher prevalence of acromegaly in the adult population than that reported traditionally. We propose that screening based on phenotypic alterations is cost-effective since these changes occur early and almost universally in acromegaly and are uncommon in the general population.

What is active acromegaly and which parameters do we have?

Disease activity of acromegaly can be measured in many ways. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) concentrations are the main biochemical markers used to measure the response to treatment. Both GH and IGF1 have been associated with prognosis, in particular mortality. In this review, we discuss the available parameters to assess disease activity in acromegaly.

Janus kinase (JAK) 2 V617F mutation as the cause of primary thrombocythemia in acromegaly with severe visceromegaly and divergence between growth hormone and insulin-like growth factor-1 concentrations during the follow-up: causal or casual association?

OBJECTIVE

An increased prevalence of hematological abnormalities is reported in acromegaly, but to date no reports about the presence of the Janus Kinase (JAK) 2 mutation in acromegalic patients have been described.

DESIGN

We report the complex clinical presentation of the unique case, never described, of acromegaly due to GH-secreting pituitary adenoma associated with JAK2 V617F mutation.

RESULTS

The patient shows primary thrombocythemia and myelofibrosis, due to JAK2 V617F mutation, severe visceromegaly and a peculiar clinical course of the disease characterized by discrepant values of GH and IGF-1 during somatostatin analog (SA) treatment despite a significant reduction in pituitary adenoma size and therapeutic resistance both to SA and pegvisomant.

CONCLUSIONS

The presence of JAK2 V617F mutation is a cause of primary thrombocythemia and myelofibrosis in acromegaly. In this patient, a peculiar clinical course of acromegaly was observed, with the difficulty in controlling the disease. More data, on a larger cohort of patients, could clarify whether JAK2 V617F mutation has a serious impact on the clinical features and course of acromegaly.

Medical therapy of acromegaly

This paper outlines the present status of medical therapy of acromegaly. Indications for permanent postoperative treatment, postirradiation treamtent to bridge the interval until remission as well as primary medical therapy are elaborated. Therapeutic efficacy of the different available drugs-somatostatin receptor ligands (SRLs), dopamine agonists, and the GH antagonist Pegvisomant-is discussed, as are the indications for and efficacy of their respective combinations. Information on their mechanism of action, and some pharmakokinetic data are included. Special emphasis is given to the difficulties to define remission criteria of acromegaly due to technical assay problems. An algorithm for medical therapy in acromegaly is provided.

Comparison of oral glucose tolerance test (OGTT) 100 g with OGTT 75 g for evaluation of acromegalic patients and the impact of gender on test reproducibility

CONTEXT

Growth hormone (GH) measurements during an oral glucose tolerance test (OGTT) are essential for the diagnosis and follow-up management of acromegaly. However, both 100 g glucose (OGTT(100) ) and 75 g glucose (OGTT(75) ) test variants are in clinical use. Whether the tests are interchangeable concerning GH nadir and test interpretation is unclear. Furthermore, information on test reproducibility and the impact of gender is scarce.

OBJECTIVE

To compare both tests in acromegalic patients and to evaluate test reproducibility with respect to gender.

DESIGN, SUBJECTS AND METHODS

OGTT(100) and OGTT(75) were performed on two consecutive days in 54 acromegalic patients (46·9 ± 1·8 years, 30 women). OGTT(75) was repeated on three different occasions in 11 healthy men and 13 healthy women at different phases of the menstrual cycle.

RESULTS

GH nadirs were comparable between tests [2·40 ± 0·52 (OGTT(100) ) and 2·46 ± 0·54 μg/l (OGTT(75) ); P = 0·356]. There were no differences at any time point in the mean values of GH, serum glucose or insulin between the two test variants. Test interpretation was highly consistent between the OGTT(100) and OGTT(75) [area under the receiver operated curve (ROC) = 0·995]. In men, GH, insulin and glucose measurements during OGTT(75) were highly reproducible. In women, however, basal and GH nadirs were significantly higher midcycle (P < 0·05).

CONCLUSIONS

In acromegalic patients, there is no difference in GH nadirs and test interpretation after the ingestion of 100 g or 75 g glucose. The OGTT(75) is highly reproducible in men, but in women, it should be performed preferably in the early follicular phase.

Frequency of acromegaly in adults with diabetes or glucose intolerance and estimated prevalence in the general population

The objective of this study was to evaluate the frequency of acromegaly in adults with diabetes mellitus (DM) or glucose intolerance (GI) and to estimate its prevalence in the general population. A total of 2,270 patients with DM or GI and age from 20 to 70 years were studied. Patients with known pituitary disease and pregnant women were excluded. Serum IGF-1 was measured in all subjects and, if elevated, a new measurement was obtained together with the measurement of GH in the oral glucose tolerance test (OGTT). Patients with persistently elevated IGF-1 and inadequate suppression of GH were submitted to magnetic resonance imaging (MRI). Acromegaly was not suspected by the assistant physician in any of the patients. Six patients had persistently elevated IGF-1 and inadequate suppression of GH in the OGTT (without other conditions associated with GH or IGF-1 elevation). Pituitary adenoma was detected by MRI in three patients, and two subjects presented an acromegalic phenotype. Two patients were submitted to transsphenoidal surgery, with immunohistochemistry confirming immunoreactivity for GH. Another patient was treated with octreotide LAR which resulted in the normalization of IGF-1 and GH. Considering a prevalence of DM or GI of 20% in adults and the occurrence of these co-morbidities in 55% of patients with acromegaly, the frequency of 3/2,270 found in this study permits to estimate 480 cases/1,000,000 adults. The present results suggest that the prevalence of acromegaly is underestimated and further studies are needed to evaluate the cost-effectiveness of biochemical screening in certain groups of patients.

Clinically silent somatotroph adenomas are common

OBJECTIVE

Somatotroph adenomas are typically recognized when they secrete GH excessively and cause acromegaly. Both 'silent' somatotroph adenomas (immunohistochemical evidence of GH excess without biochemical or clinical evidence) and 'clinically silent' somatotroph adenomas (immunohistochemical and biochemical evidence but no clinical evidence) have occasionally been reported. The relative frequency of each presentation is unknown. The goal of this study was, therefore, to determine the frequency of clinically silent somatotroph adenomas, a group that is potentially recognizable in vivo.

DESIGN

We retrospectively identified 100 consecutive patients who had surgically excised and histologically confirmed pituitary adenomas.

METHODS

Each pituitary adenoma was classified immunohistochemically by pituitary cell type. Somatotroph adenomas were further classified as 'classic' (obvious clinical features of acromegaly and elevated serum IGF1), 'subtle' (subtle clinical features of acromegaly and elevated IGF1), 'clinically silent' (no clinical features of acromegaly but elevated IGF1), and 'silent' (no clinical features of acromegaly and normal IGF1).

RESULTS

Of the 100 consecutive pituitary adenomas, 29% were gonadotroph/glycoprotein, 24% somatotroph, 18% null cell, 15% corticotroph, 6% lactotroph, 2% thyrotroph, and 6% not classifiable. Of the 24 patients with somatotroph adenomas, classic accounted for 45.8%, subtle 16.7%, clinically silent 33.3%, and silent 4.2%.

CONCLUSIONS

Clinically silent somatotroph adenomas are more common than previously appreciated, representing one-third of all somatotroph adenomas. IGF1 should be measured in all patients with a sellar mass, because identification of a mass as a somatotroph adenoma expands the therapeutic options and provides a tumor marker to monitor treatment.

[Consensus on the change of criteria for cure of acromegaly during the last decade]

The Acromegaly Consensus Group redefined the consensus criteria for cure of acromegaly. 74 neurosurgeons and experienced endocrinologists summarized the latest results on diagnosis and treatment of acromegaly. In this consensus statement the reliable growth hormone and insulin-like growth factor-1 assays were established. Definition of disease control was discussed based on the available publications and evidence. This short communication summarizes the clinical aspects of consensus criteria for diagnosis and cure of acromegaly based on the original article.

A consensus on criteria for cure of acromegaly

OBJECTIVE

The Acromegaly Consensus Group met in April 2009 to revisit the guidelines on criteria for cure as defined in 2000.

PARTICIPANTS

Participants included 74 neurosurgeons and endocrinologists with extensive experience of treating acromegaly. EVIDENCE/CONSENSUS PROCESS: Relevant assays, biochemical measures, clinical outcomes, and definition of disease control were discussed, based on the available published evidence, and the strength of consensus statements was rated.

CONCLUSIONS

Criteria to define active acromegaly and disease control were agreed, and several significant changes were made to the 2000 guidelines. Appropriate methods of measuring and achieving disease control were summarized.