Is GH nadir during OGTT a reliable test for diagnosis of acromegaly in patients with abnormal glucose metabolism?

Laboratory Testing for Endocrine Hypertension: Current and Future Perspectives

BACKGROUND

Secondary hypertension (SH) is a form of high blood pressure caused by an identifiable underlying condition. Although, it accounts for a small fraction of the overall hypertensive population, detection and management of SH is of utmost importance, because SH phenotypes carry a high cardiovascular risk and can possibly be cured by timely treatment.

CONTENT

This review focuses on the endocrine causes of SH, such as primary aldosteronism, Cushing syndrome, thyroid disease, pheochromocytoma and paraganglioma, acromegaly, and rare monogenic forms. It discusses current biomarkers, analytical methods, and diagnostic strategies, highlighting advantages and limitations of each approach. It also explores the emerging -omics technologies that can provide a comprehensive and multidimensional assessment of SH and its underlying mechanisms.

SUMMARY

Endocrine SH is a heterogeneous and complex condition that requires proper screening and confirmatory tests to avoid diagnostic delays and improve patient outcomes. Careful biomarker interpretation is essential due to potential interferences, variability, and method-dependent differences. Liquid chromatography-tandem mass spectrometry is a superior method for measuring low-concentration hormones and metabolites involved in SH, but it requires expertise. Omics approaches have great potential to identify novel biomarkers, pathways, and targets for SH diagnosis and treatment, especially considering its multifactorial nature.

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.

Diagnosis and Management of Pituitary Adenomas: A Review

Importance

Pituitary adenomas are neoplasms of the pituitary adenohypophyseal cell lineage and include functioning tumors, characterized by the secretion of pituitary hormones, and nonfunctioning tumors. Clinically evident pituitary adenomas occur in approximately 1 in 1100 persons.

Observations

Pituitary adenomas are classified as either macroadenomas (≥10 mm) (48% of tumors) or microadenomas (<10 mm). Macroadenomas may cause mass effect, such as visual field defects, headache, and/or hypopituitarism, which occur in about 18% to 78%, 17% to 75%, and 34% to 89% of patients, respectively. Thirty percent of pituitary adenomas are nonfunctioning adenomas, which do not produce hormones. Functioning tumors are those that produce an excess of normally produced hormones and include prolactinomas, somatotropinomas, corticotropinomas, and thyrotropinomas, which produce prolactin, growth hormone, corticotropin, and thyrotropin, respectively. Approximately 53% of pituitary adenomas are prolactinomas, which can cause hypogonadism, infertility, and/or galactorrhea. Twelve percent are somatotropinomas, which cause acromegaly in adults and gigantism in children, and 4% are corticotropinomas, which secrete corticotropin autonomously, resulting in hypercortisolemia and Cushing disease. All patients with pituitary tumors require endocrine evaluation for hormone hypersecretion. Patients with macroadenomas additionally require evaluation for hypopituitarism, and patients with tumors compressing the optic chiasm should be referred to an ophthalmologist for formal visual field testing. For those requiring treatment, first-line therapy is usually transsphenoidal pituitary surgery, except for prolactinomas, for which medical therapy, either bromocriptine or cabergoline, is usually first line.

Conclusions and Relevance

Clinically manifest pituitary adenomas affect approximately 1 in 1100 people and can be complicated by syndromes of hormone excess as well as visual field defects and hypopituitarism from mass effect in larger tumors. First-line therapy for prolactinomas consists of bromocriptine or cabergoline, and transsphenoidal pituitary surgery is first-line therapy for other pituitary adenomas requiring treatment.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

The Biochemical Diagnosis of Acromegaly

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