Discordance between growth hormone and insulin-like growth factor-1 after pituitary surgery for acromegaly: a stepwise approach and management

Cocaine-Induced Apoplexy of a GH-Secreting Pituitary Tumor

A 25-year-old previously healthy man presents to the clinic with a severe headache after cocaine consumption. Physical examination revealed acromegaloid features, and the hormonal profile revealed an IGF-1 of 308 ng/mL (40.8 nmol/L) (normal reference range 197-333 ng/mL; 17.8-45.6). An MRI showed a heterogeneous, cystic lesion of the pituitary gland with hematic contents, consistent with the diagnosis of a pituitary apoplexy. Considering the normal IGF-1 level, the patient was classified to be in remission, which deems it unnecessary to initiate pharmacologic or surgical treatment. Remission of acromegaly after a pituitary apoplexy is an extremely rare event, and pituitary apoplexy after cocaine consumption is also anecdotal. We present the first case of remission of acromegaly after a cocaine-induced pituitary apoplexy.

Trends of correlations between serum levels of growth hormone and insulin-like growth factor-I in general practice

Serum levels of growth hormone (GH) and insulin-like growth factor (IGF)-I are crucial in the diagnosis and management of GH-related diseases. However, these levels are affected by nutritional and metabolic status. To elucidate the correlations between GH and IGF-I in various conditions, a retrospective analysis was performed for adult patients in which GH levels were examined by general practitioners during the period from January 2019 to December 2021. Of 642 patients, 33 patients were diagnosed with acromegaly, 21 were diagnosed with GH deficiency (GHD), and 588 were diagnosed with non-GH-related diseases (NGRD). In contrast to the positive correlations found between the levels of GH and IGF-I in patients with acromegaly (R=0.50; P<0.001) and patients with GHD (R=0.39; P=0.08), a negative correlation was found in the NGRD group (R=-0.23; P<0.001). In that group, the results of multivariable analysis showed that GH levels were predominantly influenced by gender and body mass index (BMI), whereas IGF-I levels were modulated by albumin in addition to age and GH. Of note, in the NGRD group, there was an enhanced negative correlation between GH and IGF-I under conditions of BMI < 22 and albumin < 4.0 g/dL (R=-0.45; P<0.001), and the negative correlation between GH and IGF-I was reinforced by excluding patients with other pituitary diseases and patients taking oral steroids (R=-0.51; P<0.001 and R=-0.59; P<0.001, respectively). Collectively, the results indicate that attention should be given to the presence of a negative correlation between serum levels of GH and IGF-I, especially in lean and low-nutritious conditions.

Impact of Variation between Assays and Reference Intervals in the Diagnosis of Endocrine Disorders

Method-related variations in the measurement of hormones and the reference intervals used in the clinical laboratory can have a significant, but often under-appreciated, impact on the diagnosis and management of endocrine disorders. This variation in laboratory practice has the potential to lead to an errant approach to patient care and thus could cause harm. It may also be the source of confusion or result in excessive or inadequate investigation. It is important that laboratory professionals and clinicians know about these impacts, their sources, and how to detect and mitigate them when they do arise. In this review article, we describe the historical and scientific context from which inconsistency in the clinical laboratory arises. Examples from the published literature of the impact of the method, reference interval, and clinical decision threshold-related discordances on the assessment and monitoring of various endocrine disorders are discussed to illustrate the sources, causes, and effects of this variability. Its potential impact on the evaluation of growth hormone deficiency and excess, thyroid and parathyroid disorders, hyperandrogenism, hypogonadism, glucocorticoid excess and deficiency, and diabetes mellitus is elaborated. Strategies for assessment and mitigation of the discordance are discussed. The clinical laboratory has a responsibility to recognise and address these issues, and although a lot has been accomplished in this area already, there remains more to be done.

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.

Evaluating the Impact of Acromegaly on Quality of Life

Acromegaly has a substantial negative impact on quality of life (QoL). This review aims to discuss the impact of acromegaly on QoL from the clinical perspective as well as from the patient perspective. Furthermore, it aims to evaluate the use of patient-reported outcome measures (PROMs) in acromegaly and how PROMs aid decision-making. The recommendations presented in this review are based on recent clinical evidence on the impact of acromegaly on QoL combined with the authors' own clinical experience treating patients with acromegaly. We recommend that a patient-centered approach should be considered in treatment decisions, integrating conventional biochemical outcomes, tumor control, comorbidities, treatment complications, and PROMs, including QoL measures. This more integrated approach seems effective in treating comorbidities and improving patient-reported outcomes and is critical, as many patients do not achieve biochemical or tumor control and comorbidities, impairment in QoL may not remit even when full biochemical control is achieved.

State of the Art of Patient-reported Outcomes in Acromegaly or GH Deficiency: A Systematic Review and Meta-analysis

CONTEXT

Insight into the current landscape of patient-reported outcome (PRO) measures (PROM) and differences between PROs and conventional biochemical outcomes is pivotal for future implementation of PROs in research and clinical practice. Therefore, in studies among patients with acromegaly and growth hormone deficiency (GHD), we evaluated (1) used PROMs, (2) their validity, (3) quality of PRO reporting, (4) agreement between PROs and biochemical outcomes, and (5) determinants of discrepancies.

EVIDENCE ACQUISITION

We searched 8 electronic databases for prospective studies describing both PROs and biochemical outcomes in acromegaly and GHD patients. Quality of PRO reporting was assessed using the International Society for Quality of Life Research (ISOQOL) criteria. Logistic regression analysis was used to evaluate determinants.

EVIDENCE SYNTHESIS

Ninety studies were included (acromegaly: n = 53; GHD: n = 37). Besides nonvalidated symptom lists (used in 37% of studies), 36 formal PROMs were used [predominantly Acromegaly Quality of Life Questionnaire in acromegaly (43%) and Quality of Life-Assessment of Growth Hormone Deficiency in Adults in GHD (43%)]. Reporting of PROs was poor, with a median of 37% to 47% of ISOQOL items being reported per study. Eighteen (34%) acromegaly studies and 12 (32%) GHD studies reported discrepancies between PROs and biochemical outcomes, most often improvement in biochemical outcomes without change in PROs.

CONCLUSIONS

Prospective studies among patients with acromegaly and GHD use a multitude of PROMs, often poorly reported. Since a substantial proportion of studies report discrepancies between PROs and biochemical outcomes, PROMs are pivotal in the evaluation of disease activity. Therefore, harmonization of PROs in clinical practice and research by development of core outcome sets is an important unmet need.

Dynamic Tests in Pituitary Endocrinology: Pitfalls in Interpretation during Aging

Aging and age-related diseases represent hot topics of current research. Progressive damage in morphology and function of cells and tissue characterizes the normal process of aging that is influenced by both genetic and environmental factors. The ability of each individual to adapt to these stressors defines the type of aging and the onset of age-related diseases (i.e., metabolic syndrome, inflammatory disorders, cancer, and neurodegenerative diseases). The endocrine system plays a critical role in this process because of its complex relationships with brain, immune system, and skeletal muscle; thus, alterations in hormonal networks occur during aging to maintain homeostasis, with consequent under- or overactivity of specific hypothalamic-pituitary-peripheral hormone axes. On the other hand, the increase in life expectancy has led to increasing incidence of age-related diseases, including endocrine disorders, which may prompt assessment of endocrine function in aging individuals. In this context, there is growing awareness that natural changes of endocrine physiology and physiopathology occurring with increasing age may necessitate age-driven diagnostic cutoffs requiring validation in the elderly. This review aims to analyze the available literature on the hormone response to the most important dynamic tests currently used in the clinical practice for the screening of anterior pituitary-related diseases to underline pitfalls in interpretation during aging.

Course and outcomes of pregnancy in women treated for acromegaly: Discerning a contemporary cohort

OBJECTIVE

To analyze pregnancy course and outcomes in women treated for acromegaly and compare outcomes based on disease activity at the time of conception.

DESIGN

Retrospective study.

PATIENTS

Women with acromegaly diagnosed prior to or during pregnancy from 2010 to 2019, representing cases (14 pregnancies in 12 cases), were later stratified based on active (n = 5) or controlled disease (n = 9) at time of conception. Female acromegalic patients over the same period constituted the 'acromegaly cohort' (AC) (n = 75).

RESULTS

All cases had macroadenomas with nadir GH of 15.06 ng/ml (IQR 9-30), IGF-I index of 3.04 (1.96-3.82), for which they had undergone pituitary surgery; except two patients diagnosed during pregnancy, who received pharmacotherapy followed by surgery 4 months postpartum. Adjuvant pharmacotherapy was required in 71.4% patients and radiotherapy in 35.7%. Pregnancy occurred at a median of 2 (0.8-5.1) years after surgery and 21.4% required assisted reproduction. All had term delivery with normal APGAR except one case with gestational hypertension, who delivered a preterm baby. None had congenital malformations. Despite higher baseline IGF-I, GH and tumor volume in those with pre-conceptional active acromegaly, materno-fetal outcomes were not different from those with controlled disease (p > 0.05). Similar or greater proportion of cases had normal GH and no residual tumor postpartum, even in those with pre-conceptional active acromegaly.

CONCLUSION

The current study showed conducive outcomes of gestation in women treated for acromegaly and no higher rates of pregnancy parameters or complications than non-acromegaly pregnancies in the same population. Active acromegaly does not seem to have an adverse bearing on outcomes.

Treatment of acromegaly by rosiglitazone via upregulating 15-PGDH in both pituitary adenoma and liver

Rosiglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPARγ) ligand, has been reported to reduce growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in 10 patients with acromegaly. However, the mechanisms remain unknown. Here, we reveal that PPARγ directly enhances 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, whose expression is decreased and negatively correlates with tumor size in acromegaly. Rosiglitazone decreases GH production and promotes apoptosis and autophagy in GH3 and primary somatotroph adenoma cells and suppresses hepatic GH receptor (GHR) expression and IGF-1 secretion in HepG2 cells. Activating the PGE2/cAMP/PKA pathway directly increases GHR expression. Rosiglitazone suppresses tumor growth and decreases GH and IGF-1 levels in mice inoculated subcutaneously with GH3 cells. The above effects are all dependent on 15-PGDH expression. Rosiglitazone as monotherapy effectively decreases GH and IGF-1 levels in all nineteen patients with active acromegaly. Evidence suggests that rosiglitazone may be an alternative pharmacological approach for acromegaly by targeting both pituitary adenomas and liver.

Prognostic factors of biochemical remission after transsphenoidal surgery for acromegaly: a structured review

PURPOSE

Biochemical control is the main determinant of survival, clinical manifestations and comorbidities in acromegaly. Transsphenoidal selective adenomectomy (TSA) is the initial treatment of choice with reported biochemical remission rates varying between 32 and 85%. Understanding the limiting factors is essential for identification of patients who require medical treatment.

METHODS

We reviewed the English literature published in Medline/Pubmed until Dec 31, 2019 to identify eligible studies that described outcomes of TSA as primary therapy and performed analyses to determine the main predictors of remission.

RESULTS

Most publications reported single-institution, retrospective studies. The following preoperative parameters were consistently associated with lower remission rates: cavernous sinus invasion by imaging, larger tumor size and higher GH levels. Young age and preoperative IGF-1 levels were predictive in some studies. When controlled for covariates, the best single preoperative predictor was cavernous sinus invasion, followed by preoperative GH levels. Conversely, low GH level in the first few days postoperatively was a robust predictor of durable remission. The influence of tumor histology (sparsely granular pattern, co-expression of prolactin and proliferation markers) on surgical remission remains to be established. Few studies developed predictive models that yielded much higher predictive values than individual parameters.

CONCLUSION

Surgical outcome prognostication systems could be further generated by machine learning algorithms in order to support development and implementation of personalized care in patients with acromegaly.

Serum phosphate: Does it more closely reflect the true state of acromegaly?

An increased serum phosphate (P) level is common in acromegaly patients, however, the relationships among P, growth hormone (GH), insulin-like growth factor 1 (IGF-1) and disease status remain unknown. To reveal these relationships, we examined the association of P with comprehensive clinical data. We measured the serum P, calcium, GH, oral glucose tolerance test-GH (OGTT-GH), IGF-1, and insulin-like growth factor binding protein-3 (IGBP-3) levels in 103 acromegaly patients. SAGIT® was used to assess the disease status comprehensively. Spearman's rank correlation coefficient was obtained to evaluate the associations among the above parameters. Stepwise multiple linear regression analysis was performed to investigate factors independently associated factors with the SAGIT scores. The area under the receiver operating characteristic curve (AUCROC) was used to evaluate the efficacy of the percentage change in the serum phosphate level in predicting remission in patients with postoperatively discordant GH and IGF-1 levels. Hyperphosphatemia was found in 68.9% of patients at baseline. The serum P level was higher in the non-remission group, but no correlation was found between hyperphosphatemia and remission. We revealed a significant correlation between the P level and SAGIT® score in patients both preoperatively (r = 0.659, p = 0.000) and 1-year postoperatively without remission patients (r = 0.534, p = 0.027). All biochemical levels decreased significantly postoperatively, and the GH and OGTT-GH levels achieved early stability (1 month); however, the P, IGF-1 and IGBP-3 levels showed a gradual decline. A percentage change in P of -8.12% is recommended as a cut-off value for predicting remission in patients with postoperatively discordant GH and IGF-1 levels. As a metabolic product which affected by the GH/IGF-1 axis, serum P appears to more closely reflect the comprehensive disease status in acromegaly. When the GH and IGF-1 levels are discordant during follow-up, perioperative change in the P level may be a potential predictor of remission.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement

The Korean Endocrine Society (KES) published clinical practice guidelines for the treatment of acromegaly in 2011. Since then, the number of acromegaly cases, publications on studies addressing medical treatment of acromegaly, and demands for improvements in insurance coverage have been dramatically increasing. In 2017, the KES Committee of Health Insurance decided to publish a position statement regarding the use of somatostatin analogues in acromegaly. Accordingly, consensus opinions for the position statement were collected after intensive review of the relevant literature and discussions among experts affiliated with the KES, and the Korean Neuroendocrine Study Group. This position statement includes the characteristics, indications, dose, interval (including extended dose interval in case of lanreotide autogel), switching and preoperative use of somatostatin analogues in medical treatment of acromegaly. The recommended approach is based on the expert opinions in case of insufficient clinical evidence, and where discrepancies among the expert opinions were found, the experts voted to determine the recommended approach.

Delayed Remission of Growth Hormone-Secreting Pituitary Adenoma After Transsphenoidal Adenectomy

OBJECTIVE

To investigate the clinical characteristics of delayed remission (DR) of growth hormone (GH)-secreting pituitary adenoma after transsphenoidal adenectomy and inform follow-up treatments.

METHODS

We retrospectively reviewed 87 patients who had undergone transsphenoidal surgery for acromegaly. Demographic, radiological, and endocrinological data were reviewed before, immediately after, 3 months after, and in the long term (2.4 ± 1.1 years) after surgery. The definition of DR was that patients did not achieve GH remission immediately, 3 months, or later after surgery, but did so in the long term without any additional postoperative treatment.

RESULTS

Fifty-one patients (58.6%) achieved long-term GH remission. There were 24 (27.6%) DR patients immediately postoperatively and 9 (10.3%) DR patients 3 months postoperatively. On average, the 24 DR patients achieved remission at 10.2 (range, 3-32) months. Immediate postoperative random and nadir GH after an oral glucose load were significantly lower in the DR group than in the nonremission group (2.73 ± 3.17 and 2.03 ± 2.59 vs. 8.05 ± 10.35 and 5.55 ± 5.91 μg/L, respectively). Three-month postoperative nadir GH was significantly lower in the DR group than in the nonremission group (1.63 ± 2.82 vs. 3.48 ± 4.25 μg/L, P = 0.007). Immediate postoperative random GH effectively predicted long-term remission (Spearman's ρ = 0.513, area under the curve = 0.905 > 0.90). However, the best predictor of long-term remission was 3-month postoperative nadir GH (Spearman's ρ = 0.728, area under the curve = 0.944 > 0.90), with 76.5% sensitivity and 97.2% specificity.

CONCLUSIONS

For certain groups of patients likely to achieve DR, additional treatments should not be performed early after surgery. Prolonged follow-up and close observation could help determine the therapeutic effect of surgery and guide postoperative treatments.

The efficacy of medical treatment in patients with acromegaly in clinical practice

Although somatostatin analogues (SSAs) are recommended as the first-line medical therapy for acromegaly, dopamine agonists (DAs) are also a therapeutic option for treatment. We aimed to assess and compare the efficacies of DAs and SSAs in treating acromegaly in clinical practice. We included 89 patients with acromegaly who took DAs (bromocriptine [BCT], n = 63; cabergoline [CAB], n = 11) or SSAs (n = 15) as a primary medical therapy for more than 3 months in the Seoul National University Hospital. The CAB (45.5%) and SSA (33.3%) groups achieved random GH levels of <2.5 ng/mL and the normal IGF-1 levels were significantly higher than in the BCT group (11.1%) (p = 0.009). We further included all the patients with acromegaly (n = 132) who had taken CAB, BCT, and SSAs as first- or second-line medical therapy. The CAB group showed similar efficacy as the SSA group in terms of the GH and insulin-like growth factor-1 (IGF-1) levels (57.6% for random GH level <2.5 ng/mL, 42.4% for normal IGF-1 levels, 36.4% for both). Logistic regression analysis revealed that medications, age, GH level, or IGF-1 level before medication, hyperprolactinemia, and prior gamma-knife surgery or radiation therapy, did not affect the therapeutic response. High pretreatment GH levels predicted poor treatment outcomes (odds ratio [95% confidence interval] = 0.95 [0.90-0.99]). CAB was effective in treating acromegaly at a relatively lower cost in patients with low pretreatment GH levels.

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.

Prolonged preoperative treatment of acromegaly with Somatostatin analogs may improve surgical outcome in patients with invasive pituitary macroadenoma (Knosp grades 1-3): a retrospective cohort study conducted at a single center

BACKGROUND

This study aimed to investigate preoperative somatostatin analogs (SSAs) treatment on the surgical outcome in patients with acromegaly.

METHODS

An analysis of 358 patients with acromegaly was conducted. The preoperative medical therapy group (81 patients) received SSA treatment for at least 3 months prior to surgery, while the primary surgery group (277 patients) underwent transsphenoidal surgery directly. Follow-up duration was ≥3 months. Tumor invasion was evaluated by magnetic resonance imaging (MRI) and classified according to the Knosp grading system.

RESULTS

Most patients were diagnosed with macroadenoma. Among all patients (Knosp grades 0-4), preoperative SSA therapy did not significantly improve the curative effect of surgery, according to the levels of growth hormone (GH) and/or insulin-like growth factor 1 (IGF-1) markers. In patients with macroadenoma (Knosp grades 1-3), the remission rates were significantly higher in the SSA group compared to the surgery group when considering GH (56.4% vs. 37.3%, P = 0.048) and IGF-1 (43.2% vs. 17.6%, P = 0.004). In the preoperative medical therapy group, long-term use of SSAs (>6 months) led to higher remission rates (GH, 72.2% vs. 51.0%; and IGF-1, 61.1% vs. 29.8%; P = 0.12 and 0.02, respectively].

CONCLUSIONS

The long-term preoperative SSAs treatment may improve the surgical curative rate in acromegalic patients with invasive macroadenomas (Knosp grades 1-3).

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

OBJECTIVE

Growth hormone (GH) and insulin-like growth factor I (IGF-I) are the principal biomarkers used to assess disease activity in acromegaly, and any discrepancy between them renders interpretation of results inconclusive. Purpose of this study was to assess the frequency of this discrepancy and identify parameters that might affect its occurrence.

DESIGN

A systematic review of MEDLINE and Scopus was performed (1987-2013) followed by a meta-analysis to address the frequency of discrepant results between GH and IGF-I levels. Meta-regression and subgroup analyses were performed assessing the effects of the year of publication, the different types of GH testing and GH assays used, as well as the impact of treatment with somatostatin analogues (SSAs) on the occurrence of this discrepancy.

RESULTS

The analysis retrieved 39 eligible studies totalling 7071 patients. The pooled discordance rate between GH and IGF-I was 25·7% (95% CI: 22·3-29·4), and the predominant format was that of elevated IGF-I with normal GH levels (15·3%, 95% CI: 12·5-18·7). No significant correlation between the discordance rate and the year of publication was shown; whereas, the use of ultrasensitive GH assays resulted in higher discordance rates (30·7%, 95% CI: 25·9-35·9 vs 19·8%, 95% CI: 14·1-27·2, P = 0·04) as did treatment with SSAs (32·5%, 95% CI: 27·8-37·4) vs (21·6%, 95% CI: 17·8-25·6, P = 0·001).

CONCLUSIONS

Discrepancy between GH and IGF-I results is encountered in a quarter of treated patients with acromegaly, especially when using ultrasensitive GH assays or in patients receiving SSAs, a fact that the clinician should take into consideration when making clinical decisions.

DISCORDANCE BETWEEN GH AND IGF-1 LEVELS IN TURKISH ACROMEGALIC PATIENTS

OBJECTIVE

Discordance between insulin-like growth factor-1 (IGF-1) and growth hormone (GH) levels is an important problem in the follow-up of patients diagnosed with acromegaly. Our aims were to evaluate the discordance between IGF-1 and GH levels and compare the performance of different cut-off levels for the nadir in GH (GHn) in acromegalic patients.

METHODS

The study included 63 acromegalic patients in a follow-up at a tertiary care university hospital facility. Levels of IGF-1, IGF binding protein-3 (IGFBP-3), and GH were investigated. The baseline GH and GHn levels were evaluated after an oral glucose tolerance test (cut-offs of 0.4 and 1 ng/mL, respectively). The discordance rates between GHn and IGF-1 levels, and IGF-1/IGFBP-3 ratios were determined.

RESULTS

We first adopted a GHn cut-off value of 1 ng/mL and found that 27 patients (42.9%) exhibited biochemical remission (BR) (IGF-1 <95^th percentile, GH <1), and 25 patients (39.7%) had no BR (NBR) (IGF-1 ≥95^th percentile, GH >1). Discordance in the presence of normal IGF-1 and nonsuppressed GH (DC1) occurred in 2 of 63 (3.2%) patients; discordance in the presence of high IGF-1 and suppressed GH (DC2) occurred in 9 of 63 (14.3%) patients. If the GHn cut-off value adopted was 0.4 ng/mL, the distributions were 17 of 63 (27.0%) patients in BR, 29 of 63 (46.0%) patients in NBR, 12 of 63 (19.0%) in DC1, and 5 of 63 (7.9%) patients in DC2. If only the baseline GH values were considered, the distributions were very similar to those with a GHn cut-off value of 0.4 ng/mL. The IGF-1/IGFBP-3 ratio was lowest in the BR group.

CONCLUSION

Adopting a GHn cut-off value of 0.4 ng/mL did not increase the test performance compared with baseline GH only. In contrast, in the follow-up of acromegalic patients, the IGF-1/IGFBP-3 ratio might be a useful measurement when discordance between IGF-1 and GH levels occurs. We propose that these values be considered in clinical practice.

ABBREVIATIONS

BR = biochemical remission DC1 = discordance group 1 DC2 = discordance group 2 DM = diabetes mellitus GH = growth hormone GHn = nadir in GH IGF-1 = insulin-like growth factor-1 IGFBP-3 = IGF binding protein-3 LAR = long-acting release NBR = not in biochemical remission OGTT = oral glucose tolerance test.

Monotherapy with lanreotide depot for acromegaly: long-term clinical experience in a pituitary center

PURPOSE

Long-acting somatostatin analogs are one of the main classes of medical therapy used for acromegaly and most patients require ongoing treatment. Few studies have evaluated the long-term efficacy and safety of lanreotide depot beyond 2 years. The goal of this study was to provide a long-term longitudinal assessment of efficacy and safety of lanreotide depot in lanreotide responders compared to a surgically cured control group.

METHODS

In this retrospective longitudinal case-control study, patients with acromegaly receiving lanreotide depot monotherapy continuously for at least 24 months (N = 24) and surgically cured patients (N = 39) were compared. Serum IGF-1, pituitary MRIs, lanreotide dose, co-morbidities and adverse effects were assessed longitudinally.

RESULTS

In the lanreotide group, IGF-1 remained normal and unchanged over 6 years; comparable to the surgery only group. There was no difference in prevalence of normal IGF-1 between the lanreotide and surgery only groups at 6 months (100 vs. 97 %), 6 years (89 vs. 90 %) and at last follow-up (96 vs. 92 %). Tumor size remained stable (79 %) or decreased (21 %) in the lanreotide group. In the surgery only group, tumor size remained unchanged in all patients. Hemoglobin A1C did not differ between lanreotide and surgery only groups (baseline 5.8 vs. 6.1 %; last follow-up 6.0 vs. 5.7 %). Two (8 %) of the lanreotide and none of the surgery only group developed new diabetes mellitus.

CONCLUSION

Lanreotide depot maintains normalization of IGF-1 in 89 % of responders after 6 years, comparable to surgically cured controls, and controlled tumor size in all without significant adverse effects.

Population pharmacokinetic and pharmacodynamic analysis of tesamorelin in HIV-infected patients and healthy subjects

The objective of this analysis was to characterize the time course of selected pharmacodynamic (PD) markers of tesamorelin: growth hormone (GH) and insulin-like growth factor (IGF-1) concentrations in HIV-infected patients and healthy volunteers. A total of 41 subjects in Phase I trials receiving subcutaneous daily doses of 1 or 2 mg of tesamorelin during 14 consecutive days were included in this analysis. A previous pharmacokinetic (PK) model of tesamorelin was used as the input function for the PD model of GH. Tesamorelin was hypothesized to stimulate the secretion of GH in an "episodic" manner, i.e., for a finite duration of time. The resulting PK/PD model of GH was used to describe the time course of IGF-1. The effect of age, body weight, body mass index, sex, race, and health status on the model parameters was evaluated. The model was qualified using predictive checks and non-parametric bootstrap. Within the range of the values evaluated no covariates were significantly associated with GH or IGF-1 model parameters. Model evaluation procedures indicated accurate prediction of the selected pharmacodynamic markers. The time course of GH and IGF-1 concentrations following multiple doses of tesamorelin were well predicted by the sequential PK/PD model developed using Phase I data.