Endocrinology · PANCE / PANRE

Acromegaly

Growth hormone excess from a pituitary somatotroph adenoma; insidious enlargement of soft tissues, hands, feet, and jaw.

Also known as: acromegaly, gigantism, growth hormone-secreting adenoma, GH excess, IGF-1 excess

Overview

Chronic disease caused by sustained hypersecretion of growth hormone (GH) and consequent elevation of insulin-like growth factor 1 (IGF-1), almost always from a pituitary somatotroph adenoma. When onset is before epiphyseal closure (children), it produces gigantism; after closure, it produces acromegaly.

Epidemiology

Prevalence ~60 per million; incidence 3-4 per million per year. Equal sex distribution. Mean age at diagnosis 40-50 — typically presenting after 7-10 years of symptoms. Mortality 2-3× background if untreated, primarily from cardiovascular disease.

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Risk factors

Sporadic GH-secreting pituitary adenoma (>95%)
MEN1 — pituitary + parathyroid + pancreatic NET (menin mutation)
McCune-Albright syndrome — fibrous dysplasia, café-au-lait, precocious puberty (GNAS mutation)
Carney complex (PRKAR1A) — myxomas, lentigines
Familial isolated pituitary adenoma (AIP mutation)
Rare: ectopic GHRH from carcinoid or pancreatic NET, ectopic GH

Pathophysiology

Excess GH directly affects metabolism (insulin resistance, lipolysis) and stimulates hepatic IGF-1 production. IGF-1 drives growth of bone, cartilage, soft tissues, viscera, and vascular smooth muscle. Slow, progressive structural changes account for the delayed diagnosis. Pituitary mass effect may produce headache and bitemporal visual field defects.

Clinical presentation

Symptoms

Insidious change in hand/shoe/ring/hat size (often a key historical clue)
Coarsened facial features, prognathism, dental spacing, malocclusion
Frontal bossing, enlarged tongue, deepened voice, snoring/OSA
Hyperhidrosis, oily skin, skin tags, acanthosis nigricans
Carpal tunnel syndrome, paresthesias
Headache, bitemporal hemianopia (mass effect)
Polyuria/polydipsia (diabetes), arthralgia, fatigue, decreased libido

Signs / physical exam

Coarse facial features with frontal bossing, prognathism, widely spaced teeth
Enlarged hands and feet (spade-like)
Macroglossia, deepened voice, prominent supraorbital ridges
Skin tags, hyperhidrosis, oily skin, acanthosis nigricans
Hypertension, evidence of cardiomyopathy (S3, displaced PMI)
Visual field testing — bitemporal hemianopia if optic chiasm compressed

Classic findings

Patient who states the ring or shoes stopped fitting; old photographs show progressive facial coarsening over years.

Differential diagnosis

Familial tall stature — Childhood onset, no biochemical excess, normal IGF-1
Pseudoacromegaly — Coarse features without biochemical excess; some insulin-resistance syndromes
Hypothyroidism with myxedema — Coarse features, fatigue, weight gain; TSH and free T4 abnormal
Chronic phenytoin or minoxidil use — Drug-induced coarse features; reversible
Marfan syndrome — Tall stature, arachnodactyly, aortic root dilation; no biochemical GH/IGF-1 excess
Prognathism / dental malocclusion isolated — Skeletal variant without acral changes or biochemical confirmation

Diagnostic workup

Diagnostic criteria

Elevated age/sex-adjusted IGF-1 + failure of GH to suppress below 1 ng/mL on OGTT + pituitary lesion on MRI.

Labs

Serum IGF-1 (age- and sex-adjusted) — first-line screen; elevated above reference range supports diagnosis
Oral glucose tolerance test (OGTT) with GH suppression — confirmatory; GH should suppress to <1 ng/mL (or <0.4 with ultrasensitive assay) after 75 g oral glucose; failure to suppress confirms acromegaly
Random GH alone is not reliable (pulsatile)
Prolactin (~25% of GH adenomas also secrete prolactin)
Full anterior pituitary panel: TSH, free T4, ACTH/cortisol, FSH/LH, testosterone/estradiol
Fasting glucose and A1c (insulin resistance, diabetes)
Lipid panel, BMP, calcium (MEN1 screen)

Imaging

Pituitary MRI with gadolinium — almost always shows macroadenoma (>1 cm)
Formal Humphrey visual field testing if optic chiasm compressed
Echocardiogram — concentric LVH, biventricular hypertrophy, valvular regurgitation
Sleep study for OSA
Colonoscopy at diagnosis and routinely after (increased risk of adenomatous polyps and colon cancer)

Diagnostic algorithm

Test	Result in acromegaly	Notes
Serum IGF-1 (age/sex-matched)	Elevated	Best screening test
OGTT GH suppression	GH fails to suppress <1 ng/mL	Confirmatory; gold standard
Random GH	Variable, often elevated	Unreliable due to pulsatile release
Pituitary MRI	Macroadenoma in majority	Defines anatomy for surgery
Prolactin	Elevated in ~25%	Mixed somato-mammotroph tumors
Colonoscopy	Adenomatous polyps in many	Baseline at diagnosis

Acromegaly diagnostic testing — IGF-1 screens, OGTT confirms, MRI localizes.

Complications

Cardiovascular: hypertension, biventricular hypertrophy, cardiomyopathy, valvular disease, arrhythmia
Metabolic: diabetes mellitus, dyslipidemia
OSA (very common; often unrecognized)
Arthropathy (large joints), carpal tunnel syndrome
Colon polyps and increased colon cancer risk
Thyroid nodules and modest increase in thyroid cancer
Hypopituitarism after surgery or radiation
Visual loss from optic chiasm compression

PANCE pearls

IGF-1 is the screening test; oral glucose suppression of GH is confirmatory. Random GH alone is unreliable due to pulsatile secretion.
Old photographs are diagnostic — coarsening of features over years.
Suspect MEN1 in acromegaly + hypercalcemia/hyperparathyroidism or pancreatic NET.
Macroglossia, sweating, headache, and OSA are early clues. Carpal tunnel may be the first complaint.
Pegvisomant normalizes IGF-1 without shrinking tumor — always monitor MRI for adenoma growth.
Colon cancer screening is more aggressive in acromegaly — colonoscopy at diagnosis and every 5-10 years (or per individual risk).

References

Endocrine Society 2014 — Acromegaly: An Endocrine Society Clinical Practice Guideline (Katznelson et al., J Clin Endocrinol Metab 2014)
Pituitary Society 2020 — Multidisciplinary Management of Acromegaly: A Consensus (Melmed et al., Rev Endocr Metab Disord 2018; updated Pituitary 2020)
AACE 2011 — AACE Medical Guidelines for Clinical Practice for the Diagnosis and Treatment of Acromegaly (Katznelson et al., Endocr Pract 2011)

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