ACROMEGALY

✓ Medically ReviewedDISEASEID: MDBT0275🚨 TRIAGE: URGENTICD-10: E22.0

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Definition

CLINICAL DEFINITION

Acromegaly is a chronic, multisystem endocrine disorder caused by persistent hypersecretion of growth hormone (GH), almost always due to a GH-secreting pituitary adenoma, with consequent elevation of insulin-like growth factor 1 (IGF-1). The diagnosis is biochemically confirmed in a patient with typical clinical features when serum IGF-1 is elevated above 1.3 times the age-adjusted upper limit of normal (ULN); when results are equivocal, lack of GH suppression during an oral glucose tolerance test (OGTT) supports the diagnosis. The disease is characterised by progressive somatic disfigurement—particularly acral and craniofacial overgrowth—and by systemic complications that substantially increase morbidity and mortality if untreated.

IN PLAIN ENGLISH

Acromegaly is a rare condition in which the pituitary gland makes too much growth hormone, causing bones and tissues—especially in the hands, feet, and face—to gradually enlarge. It develops slowly over years and can lead to serious health problems if not recognised and treated.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Acromegaly is NOT simply 'large hands and feet' from normal variation or ageing; it is a biochemical diagnosis requiring documented GH excess and elevated IGF-1. It is also NOT the same as pituitary gigantism, which occurs when GH excess begins before epiphyseal closure and results in excessive linear growth rather than acral overgrowth.

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Word Breakdown

acr-

=extremity, tip (from Greek 'akron')

-megaly

=enlargement (from Greek 'megas', meaning 'great')

Literal Meaning: Enlargement of the extremities

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Abbreviations

GH=Growth Hormone — the pituitary hormone that is hypersecreted in acromegaly

IGF-1=Insulin-like Growth Factor 1 — the primary mediator of GH action, used as a diagnostic and monitoring marker

OGTT=Oral Glucose Tolerance Test — used to assess GH suppression when biochemical results are equivocal

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Category-Specific Context

Acromegaly is a Disease: a defined pathological condition with recognised biochemical diagnostic criteria and a well-characterised spectrum of severity and complications. It is distinct from a Sign or Symptom because the diagnosis requires demonstration of GH excess, not merely the observation of enlarged features.

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Clinical Context & Usage

CLINICAL SETTINGS

Endocrinology Outpatient ClinicNeurosurgery WardPituitary Multidisciplinary Team MeetingGeneral Medicine WardCardiology ClinicSleep Laboratory

USAGE & DOCUMENTATION NOTES

In clinical documentation, acromegaly is typically recorded as 'acromegaly secondary to a GH-secreting pituitary macroadenoma' when imaging is available. Biochemical status is described as 'biochemically controlled' (normal IGF-1 and GH suppression) or 'active' (elevated IGF-1). Referral letters often specify the tumour size, Knosp grade, and prior treatments. The term is not used for isolated acral enlargement without biochemical confirmation.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

The vast majority of acromegaly cases are caused by a monoclonal GH-secreting pituitary adenoma of somatotroph lineage. Excess GH binds hepatic GH receptors, stimulating IGF-1 production, which mediates many of the growth-promoting effects on bone, cartilage, and soft tissue. Chronic GH and IGF-1 excess also induces insulin resistance, sodium and water retention, and direct cardiac and respiratory effects. The insidious nature of hormonal excess means that biochemical abnormalities and complications may be present for years before the diagnosis is made.

PRIMARY CAUSES

GH-secreting pituitary adenoma

Clonal expansion of somatotroph cells leads to autonomous GH secretion, which is not suppressed by normal physiological feedback and drives hepatic IGF-1 production.

Ectopic GH-releasing hormone (GHRH) secretion

Rarely, neuroendocrine tumours (e.g., bronchial or pancreatic) secrete GHRH, causing pituitary somatotroph hyperplasia and secondary GH excess; this must be distinguished from primary pituitary disease.

Ectopic GH secretion

Exceptionally rare; some neuroendocrine tumours may secrete GH directly, producing acromegaly without a pituitary adenoma.

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Epidemiology

Prevalence:Acromegaly is a rare disease. Historical estimates placed prevalence at 30–60 cases per million, while more recent reports suggest a prevalence of approximately 70–90 cases per million, with some centres reporting rates exceeding 100 cases per million. Incidence estimates range from approximately 2 to 11 cases per million per year, with considerable variation between studies.

Age Group:Most commonly diagnosed in middle-aged adults (typically 40–50 years), but it can present at any age. Diagnostic delay is common, and the disease is increasingly recognised in older adults, partly due to incidental pituitary imaging.

Sex Predilection:Equal

Geographic Distribution:Acromegaly occurs worldwide with no clear geographic predilection. Reported variations in prevalence and incidence largely reflect differences in diagnostic practices, registry coverage, and access to pituitary imaging and biochemical testing rather than true biological variation.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 URGENT

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Progressive visual field loss or new severe headache in a patient with known or suspected acromegaly — consider pituitary apoplexy or optic chiasm compression and arrange urgent neuroimaging and neurosurgical evaluation.
Severe, refractory hyperglycaemia or diabetic ketoacidosis in a patient with acral enlargement — consider acromegaly as an underlying driver of insulin resistance and evaluate with IGF-1.

URGENT EVALUATION TRIGGERS

Sudden severe headache with visual loss or ophthalmoplegia (suspected pituitary apoplexy)
New or progressive visual field defect
Diabetic ketoacidosis or severe hyperglycaemia in a patient with features of GH excess
Chest pain or decompensated heart failure in a patient with acromegaly

Contraindications & Precautions

SPECIAL PRECAUTIONS

Biochemical testing should be interpreted with caution in patients with uncontrolled diabetes
hepatic or renal impairment
or anorexia nervosa
as these conditions can cause false-positive or equivocal GH suppression results.
OGTT should be performed with awareness that hyperglycaemia can suppress GH
and BMI-based nadir cut-offs may improve interpretation.

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Cardiovascular disease — hypertension
cardiomyopathy (biventricular hypertrophy)
valvular disease
and arrhythmias are leading contributors to morbidity and mortality
Metabolic disturbances — impaired glucose tolerance
diabetes mellitus
and dyslipidaemia are highly prevalent and amplify cardiovascular risk
Respiratory complications — obstructive sleep apnoea and ventilatory dysfunction are common and may persist after biochemical control
Musculoskeletal complications — degenerative arthropathy
vertebral fractures
myopathy
and neuropathies contribute to long-term disability
Colonic polyps and possibly colorectal cancer — increased incidence has been reported
warranting appropriate screening

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Acromegaly vs. Gigantism

Both result from GH excess, but gigantism occurs before epiphyseal closure and causes excessive linear growth, whereas acromegaly occurs after closure and causes acral and soft-tissue overgrowth.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Pseudoacromegaly

Key Distinguishing Feature: Clinical features mimicking acromegaly (e.g., pachydermoperiostosis, insulin-mediated pseudoacromegaly) but without biochemical GH excess; IGF-1 and GH suppression testing are normal.

Ectopic GHRH-secreting tumour

Key Distinguishing Feature: Biochemical GH excess is present, but pituitary imaging may show hyperplasia rather than an adenoma; serum GHRH is elevated and cross-sectional imaging may identify a neuroendocrine tumour.

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Clinical Pearls

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Diagnostic delay is the rule: symptoms are insidious and often attributed to ageing or other conditions, with delays of 5–10 years or more commonly reported. A high index of suspicion based on subtle acral or facial changes is essential.

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IGF-1 is the cornerstone of biochemical diagnosis; an elevated IGF-1 above 1.3 times the age-adjusted ULN in a patient with typical features confirms the diagnosis without routine need for OGTT.

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Biochemical control does not guarantee resolution of all complications; cardiovascular, respiratory, and musculoskeletal comorbidities may persist and require ongoing multidisciplinary management.

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Transsphenoidal surgery is first-line therapy for most patients, but remission rates depend on tumour size, invasiveness, and neurosurgeon experience; patients with persistent disease often require medical therapy with somatostatin receptor ligands, pegvisomant, or cabergoline.

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Example Usage & SOAP

CLINICAL SENTENCE

"The patient was diagnosed with acromegaly secondary to a GH-secreting pituitary macroadenoma, with elevated IGF-1 at 2.1 times the ULN and failure of GH suppression on OGTT."

IN A SOAP NOTE

S: A 48-year-old man reports gradual enlargement of his hands and feet over 8 years, with increasing shoe size and new-onset snoring. O: Blood pressure 156/94 mmHg; coarse facial features with frontal bossing and macroglossia; IGF-1 elevated at 2.4× age-adjusted ULN; GH not suppressed on OGTT. MRI pituitary shows a 14 mm macroadenoma with suprasellar extension. A: Acromegaly secondary to a GH-secreting pituitary macroadenoma, with hypertension and probable obstructive sleep apnoea. P: Refer to pituitary multidisciplinary team; arrange transsphenoidal surgery; screen for sleep apnoea and cardiac complications.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for acromegaly: (1) Pseudoacromegaly — normal IGF-1 and GH suppression; (2) Ectopic GHRH-secreting tumour — elevated GHRH, pituitary hyperplasia rather than adenoma, and imaging may reveal a neuroendocrine tumour; (3) Pituitary gigantism — GH excess before epiphyseal closure, resulting in tall stature rather than acral overgrowth.

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Classifications & Scoring

SCORING TOOL

SAGIT

A clinician-reported tool assessing Signs and symptoms, Associated comorbidities, GH level, IGF-I level, and Tumour profile; used to standardise disease activity assessment and monitor treatment response.

Clinical Calculator ↗

SCORING TOOL

ACRODAT

Acromegaly Disease Activity Tool; a software-based instrument incorporating biochemical, tumour, and comorbidity parameters to support clinical decision-making.

Clinical Calculator ↗

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Prognosis

SHORT-TERM OUTCOME

With successful transsphenoidal surgery or effective medical therapy, biochemical control can be achieved in a substantial proportion of patients, with improvement in symptoms and partial regression of soft-tissue changes. However, many patients require multimodal therapy, and complications present at diagnosis may not fully resolve.

LONG-TERM PROGNOSIS

If untreated or inadequately controlled, acromegaly is associated with increased mortality, predominantly from cardiovascular and respiratory causes, and a reduction in life expectancy. With modern multimodal management and biochemical control, mortality rates have declined and approach those of the general population in some cohorts, although residual morbidity from comorbidities remains common.

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References & Coding

ICD-10 DIAGNOSTIC CODE

E22.0

LITERATURE CITATIONS & GUIDELINES

[1]Giustina A, Biermasz N, Casanueva FF, et al. Consensus on criteria for acromegaly diagnosis and remission. Pituitary. 2024;27(1):7-22. doi:10.1007/s11102-023-01360-1

[2]Fleseriu M, Biller BMK, Freda PU, et al. A Pituitary Society update to acromegaly management guidelines. Pituitary. 2021;24(1):1-13.

[3]Katznelson L, Laws ER Jr, Melmed S, et al. Acromegaly: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2014;99(11):3933-3951.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.