Vivien Bonert

Guidelines of the Pituitary Society for the diagnosis and management of prolactinomas

In June 2005, an ad hoc Expert Committee formed by the Pituitary Society convened during the 9th International Pituitary Congress in San Diego, California. Members of this committee consisted of invited international experts in the field, and included endocrinologists and neurosurgeons with recognized expertise in the management of prolactinomas. Discussions were held that included all interested participants to the Congress and resulted in formulation of these guidelines, which represent the current recommendations on the diagnosis and management of prolactinomas based upon comprehensive analysis and synthesis of all available data.

The utility of oral glucose tolerance testing for diagnosis and assessment of treatment outcomes in 166 patients with acromegaly.

CONTEXT GH suppression after oral glucose load [oral glucose tolerance test (OGTT)] and normal age- and gender-matched IGF-I levels reflect biochemical control of acromegaly. The OGTT is the gold standard for determining control of GH secretion at diagnosis and after surgical treatment, but the usefulness of performing an OGTT in patients treated with medical therapy has not been determined. OBJECTIVE Our objective was to assess relationships between basal GH levels (basal GH), GH responses to OGTT [GH nadir (GHn)], and IGF-I levels. DESIGN This was a retrospective electronic database review. SETTING This study was performed at a tertiary outpatient pituitary center. PATIENTS A total of 166 patients with acromegaly (79 females, 87 males) were included in the study. Four categories of testing were performed: diagnosis, postoperative assessment without medication, testing during somatostatin analog (SA) therapy, and testing during dopamine agonist (DA) therapy. MAIN OUTCOME MEASURES Basal serum GH and IGF-I levels and GH levels 2 h after 75 g OGTT were measured. RESULTS A total of 482 simultaneous OGTT and IGF-I measurements were observed from 1985--2008. Discordant results of oral glucose tolerance testing (GHn and IGF-I) were observed 33, 48, and 18% in postoperative assessment without medication, SA, and DA categories, respectively. In the SA category, 42% of tests were discordant with normal IGF-I and nonsuppressed GHn. In contrast, 4% of tests were discordant with normal IGF-I and nonsuppressed GH in those treated with DA. No significant differences in discordance were observed when basal GH was used. CONCLUSIONS Both basal and GHn levels are highly discordant with IGF-I levels during medical therapy with SAs. The OGTT is not useful in assessing biochemical control in these subjects.

Acromegaly Clinical Trial Methodology Impact on Reported Biochemical Efficacy Rates of Somatostatin Receptor Ligand Treatments: A Meta-Analysis

Introduction: Biochemical efficacy of somatostatin receptor ligand (SRL) treatment in acromegaly is defined by metrics for GH and IGF-1 control. Since the earliest therapeutic trials, biochemical control criteria, medical formulations, and assay techniques have evolved. Materials and Methods: We searched PubMed for English-language trials published from 1974 to 2012 evaluating 10 or more patients, with a duration of more than 3 months and biochemical control as a key objective. We used a random-effects model to compare biochemical outcomes for octreotide and lanreotide trials according to study design characteristics. Results: A total of 4464 patients were enrolled in the analyzed trials; 4125 were treated, and 3787 completed study treatment. Overall achieved control rates were 56% for mean GH and 55% for IGF-1 normalization. Treatment duration was significantly related to both GH (P < .001) and IGF-1 control (P = .02). Prior SRL therapy (P = .01), and year of study publication (P = .03) were related to biochemical control for GH but not IGF-1. No statistically significant differences in GH or IGF-1 response rates were observed for multicenter vs single center, retrospective vs prospective, study drug, and preselection for SRL responsiveness. Dosing scheme, GH response criterion, or switch study design were also not statistically significant in determining GH or IGF-1 response rate. Conclusions: Clinical design characteristics anticipated to impart efficacy bias including switching, preselection for SRL responsiveness, and retrospective design had no statistically significant impact on efficacy determination. Later year of publication, study duration, and prior SRL use are significant efficacy determinants for acromegaly trial outcomes.

Lipodystrophy in Patients with Acromegaly Receiving Pegvisomant

CONTEXT Pegvisomant, a GH receptor antagonist, suppresses serum IGF-I levels into the normal range in more than 95% of patients with acromegaly. Documented side effects in the initial registration studies included headache, injection-site reactions, flu-like syndrome, and reversible elevation of hepatic enzymes. OBJECTIVE We report seven patients with acromegaly treated with pegvisomant who developed lipodystrophy at the site of injection (anterior abdominal wall, thigh, buttock, and upper arm). This side effect resulted in discontinuation of pegvisomant in four patients, with subsequent regression of lipohypertrophy. SUBJECTS Six female and one male patient with acromegaly, aged 24-59 yr, are reported. All patients had undergone prior transsphenoidal surgery, and four received subsequent radiotherapy. Four patients had been treated with maximal doses of somatostatin analogs with partial suppression of IGF-I levels before initiation of pegvisomant therapy. Pegvisomant suppressed IGF-I levels into the normal range in five of seven subjects, before discontinuation of the drug. Two of seven patients received pegvisomant as first-line medical therapy, without prior somatostatin analog treatment, and one received combination therapy with a long-acting somatostatin analog and weekly pegvisomant injections. One patient experienced an erythematous superficial injection-site reaction that responded to application of steroid cream before the onset of lipohypertrophy. CONCLUSIONS We report seven patients with acromegaly who developed lipohypertrophy at the pegvisomant injection site. Pegvisomant was discontinued due to dissatisfaction with lipohypertrophy by four patients. Lipohypertrophy regressed in all patients when the medication was discontinued. Lipohypertrophy recurred when two patients were rechallenged with pegvisomant. Patients receiving pegvisomant should undergo frequent examination of injection sites for lipohypertrophy.

Prolactinomas, Cushing's disease and acromegaly: debating the role of medical therapy for secretory pituitary adenomas.

Pituitary adenomas are associated with a variety of clinical manifestations resulting from excessive hormone secretion and tumor mass effects, and require a multidisciplinary management approach. This article discusses the treatment modalities for the management of patients with a prolactinoma, Cushings disease and acromegaly, and summarizes the options for medical therapy in these patients.First-line treatment of prolactinomas is pharmacotherapy with dopamine agonists; recent reports of cardiac valve abnormalities associated with this class of medication in Parkinsons disease has prompted study in hyperprolactinemic populations. Patients with resistance to dopamine agonists may require other treatment.First-line treatment of Cushings disease is pituitary surgery by a surgeon with experience in this condition. Current medical options for Cushings disease block adrenal cortisol production, but do not treat the underlying disease. Pituitary-directed medical therapies are now being explored. In several small studies, the dopamine agonist cabergoline normalized urinary free cortisol in some patients. The multi-receptor targeted somatostatin analogue pasireotide (SOM230) shows promise as a pituitary-directed medical therapy in Cushings disease; further studies will determine its efficacy and safety. Radiation therapy, with medical adrenal blockade while awaiting the effects of radiation, and bilateral adrenalectomy remain standard treatment options for patients not cured with pituitary surgery.In patients with acromegaly, surgery remains the first-line treatment option when the tumor is likely to be completely resected, or for debulking, especially when the tumor is compressing neurovisual structures. Primary therapy with somatostatin analogues has been used in some patients with large extrasellar tumors not amenable to surgical cure, patients at high surgical risk and patients who decline surgery. Pegvisomant is indicated in patients who have not responded to surgery and other medical therapy, although there are regional differences in when it is prescribed.In conclusion, the treatment of patients with pituitary adenomas requires a multidisciplinary approach. Dopamine agonists are an effective first-line medical therapy in most patients with a prolactinoma, and somatostatin analogues can be used as first-line therapy in selected patients with acromegaly. Current medical therapies for Cushings disease primarily focus on adrenal blockade of cortisol production, although pasireotide and cabergoline show promise as pituitary-directed medical therapy for Cushings disease; further long-term evaluation of efficacy and safety is important.

Macimorelin (AEZS-130)-stimulated growth hormone (GH) test: validation of a novel oral stimulation test for the diagnosis of adult GH deficiency.

Context: In the absence of panhypopituitarism and low serum IGF-I levels, the diagnosis of adult GH deficiency (AGHD) requires confirmation with a GH stimulation test. Macimorelin is a novel, orally active ghrelin mimetic that stimulates GH secretion. Objective: The objective of the study was to determine the diagnostic efficacy and safety of macimorelin in AGHD. Design: This was a multicenter open-label study comparing the diagnostic accuracy of oral macimorelin with that of arginine+GHRH in AGHD patients and healthy, matched controls. After 43 AGHD patients and 10 controls were tested, the GHRH analog Geref Diagnostic [GHRH(1–29)NH2] became unavailable in the United States. The study was completed by testing 10 additional AGHD patients and 38 controls with macimorelin alone. Main Outcome Measure: Peak GH area under the receiver operating characteristic curve after macimorelin was measured. Results: Fifty AGHD subjects and 48 controls were evaluated. Peak GH levels in AGHD patients and controls after macimorelin were 2.36 ± 5.69 and 17.71 ± 19.11 ng/mL, respectively (P < .0001). With macimorelin, the receiver operating characteristic analysis yielded an optimal GH cut point of 2.7 ng/mL, with 82% sensitivity, 92% specificity, and 13% misclassification rate. For subjects receiving both tests, macimorelin showed discrimination comparable with arginine+GHRH (area under the receiver operating characteristic curve 0.99 vs 0.94, respectively, P = .29). Obesity (body mass index > 30 kg/m2) was present in 58% of subjects, and peak GH levels were inversely associated with body mass index in controls (r = −0.37, P = .01). Using the separate cut points of 6.8 ng/mL for nonobese and 2.7 for obese subjects reduced the misclassification rate to 11%. Only 1 drug-related serious adverse event, an asymptomatic QT interval prolongation on the electrocardiogram, was reported. Conclusion: Oral macimorelin is safe, convenient, and effective in diagnosing AGHD with accuracy comparable with the arginine+GHRH test.

Pituitary tumor enlargement in two patients with acromegaly during pegvisomant therapy

BackgroundSeveral classes of pharmacological agents are approved for the medical therapy of acromegaly, including dopamine agonists, somatostatin analogs and a growth hormone receptor antagonist. Pegvisomant, a growth hormone receptor antagonist, suppresses IGF-1 levels into the normal range in over ninety percent of patients. However, increased tumor volume was reported in patients receiving pegvisomant who had not received prior radiotherapy.Objectives To describe two patients with acromegaly who developed significant tumor enlargement on pegvisomant and discuss the potential mechanisms involved.InterventionBoth patients received long-acting somatostatin analog (octreotide) therapy subsequent to incomplete transsphenoidal tumor resection. Octreotide did not normalize GH/IGF-1 levels in either patient but did control tumor mass size. Pegvisomant therapy was initiated after discontinuing octreotide.Results Both patients exhibited suppression of IGF-1 into the normal range during pegvisomant therapy. However, significant tumor enlargement occurred in both. Potential mechanisms for tumor enlargement include the natural tendency of the tumor to grow with time, discontinuation of tumor suppressive effects of the somatostatin analog, or a direct effect of pegvisomant. The presumed mechanism of tumor enlargement is by loss of the inhibitory effect on tumor growth when IGF-1 levels are reduced. This could also explain the increase in circulating GH levels in patients with acromegaly receiving pegvisomant; patient 1 demonstrated an 18–fold increase in circulating GH levels while receiving the drug.ConclusionsThe mechanisms of tumor enlargement in patients with acromegaly on pegvisomant are likely multifactorial. Patients, especially those who have not received prior radiotherapy, should be closely monitored for tumor enlargement.

Medical therapy: Options and uses

Since the initial use of medical treatment for acromegaly, several advances have been made in the understanding of the pathophysiology of growth hormone producing tumors, resulting in the development of multiple medical options and novel treatments. Currently there are three major classes of medication available for the treatment of acromegaly: somatostatin receptor ligands, growth hormone receptor antagonists, and dopamine agonists. Somatostatin receptor ligands are the treatment of choice for acromegaly due to their effectiveness in controlling growth hormone excess in approximately 60% of patients and their beneficial effects on tumor volume. Clinical trials have demonstrated efficacy of pegvisomant in up to 97% of patients, but long term data and safety have yet to be established. Dopamine agonists are inexpensive, but their use is hampered by their lack of efficacy compared to other medications. Medical therapy has an established role as adjuvant therapy after non-curative surgery, as well as primary therapy for selected patients unsuitable for surgical resection. Medical treatment to control growth hormone hypersecretion is often needed after radiation therapy until the effects are evident. Preliminary data suggest a potential role for medical treatment prior to surgical resection, surgical debulking to improve medical efficacy, and combination therapy with multiple medications from the three classes. More studies are required, however, to validate the utility of these approaches in treating acromegaly. With the available therapies, disease control can be achieved in nearly all patients with acromegaly.

Cyclic Cushing's disease with misleading inferior petrosal sinus sampling results during a trough phase

Diagnosing Cushings syndrome is challenging and is further hampered when investigations are performed in a patient with cyclic Cushings syndrome. A subset of patients with Cushings syndrome exhibit periods of abnormal cortisol secretion with interspersed normal secretion. Patients can have periods of clinical improvement during these quiescent phases or remain symptomatic. Initial diagnostic testing can be challenging because of the unpredictable durations of the peak and trough phases, and it is especially challenging when the diagnosis of cyclic Cushings syndrome has not yet been determined. Here, the authors present the case of a patient with Cushings disease with a pathology-proven adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma and whose initial inferior petrosal sinus sampling (IPSS) results were deemed indeterminate; further studies elucidated the diagnosis of cyclic Cushings syndrome. Repeat IPSS was diagnostic of a central source for ACTH secretion, and the patient was treated successfully with transsphenoidal resection. Literature concerning the diagnosis and management of cyclic Cushings syndrome is also reviewed.

4 Diagnostic challenges in acromegaly: a case-based review

Acromegaly is a rare, chronic condition caused by sustained and unregulated oversecretion of growth hormone (GH), usually attributed to a pituitary adenoma. Prolonged exposure to excessive amounts of GH and its target hormone, insulin-like growth factor-1 (IGF-1), results in pronounced metabolic changes and tissue enlargement that ultimately lead to increased morbidity and early mortality. As early diagnosis of acromegaly can have substantial beneficial effects on quality of life and overall survival for patients, it is important that the tests used to diagnose the condition are accurate, with highly reproducible results. The first kits used to measure GH and IGF-1 were radioimmunoassay, with many limitations that necessitated the development of more sensitive tools. Newer assays, although better than previous assays, are far from ideal. Simple changes that may improve the testing process include the adoption of mass units for GH interpretation and the use of a single recombinant calibrant. Furthermore, the conversion factors and reference ranges used to describe the normal limits for GH and IGF-1 levels require refinement. Physicians should be aware of the GH and IGF-1 assays used in their reference laboratories, and ensure that they know the appropriate assay cut-off values, to avoid misinterpreting results.