Acromegaly: when too much growth hormone changes your body

Acromegaly is a slow-moving condition — so slow that the average Australian patient waits five to ten years between the first subtle changes and the correct diagnosis. Rings that no longer fit, shoes purchased in a larger size, a face that looks different in photographs — these changes accumulate almost imperceptibly over years, and are frequently attributed to normal ageing until a GP or a perceptive family member connects them.

The underlying cause is a pituitary adenoma — a small, almost always non-cancerous tumour in the pituitary gland at the base of the brain — that secretes excess growth hormone continuously. In adults, this drives overgrowth not of height (the growth plates have closed) but of soft tissue, bone at the extremities, and visceral organs, while also causing metabolic disruption — insulin resistance, hypertension, and sleep apnoea — that accounts for much of the long-term cardiovascular risk.

With appropriate treatment the outlook is good, but the diagnosis must be made first.

A. Core clinical — the AU general-practice framework

Who to suspect acromegaly in

The classic presentation is an adult aged 40–50 who reports progressive changes in appearance and wellbeing over years. The history that GPs find most useful is asking a patient to bring in photographs from 10 or more years ago — comparing old and new images often makes features apparent that were invisible in a single encounter.

Features that should prompt a serum IGF-1 test:

• Rings, shoes, or hats that no longer fit — acral enlargement of fingers, feet, and skull
• Coarse facial features compared with old photographs: broadened nose, protruding jaw (prognathism), prominent brow ridges, enlarged ears, thickened lips
• New gaps between teeth from jaw growth and dental spacing changes
• Deep, husky voice from laryngeal soft tissue growth
• Excessive sweating, particularly of the face and hands, without another explanation
• Carpal tunnel syndrome — tingling or weakness in the thumb, index, and middle fingers, especially bilateral
• Joint pain — knees, hips, shoulders, and spine, from cartilage and bone changes
• Loud snoring and daytime sleepiness — sleep apnoea is common (macroglossia plus soft-tissue hypertrophy of the upper airway)
• Headaches — from the tumour itself or related hypertension
• New or worsening high blood pressure, type 2 diabetes, or dyslipidaemia without obvious explanation in a middle-aged adult
• Visual disturbance — peripheral vision loss from the tumour pressing on the optic chiasm above the pituitary

None of these features alone is specific to acromegaly. The clinical red flag is their combination in the same person, particularly when progressive over years.

Diagnostic workup

Serum IGF-1 is the first-line screening test. The Endocrine Society 2014 guideline recommends IGF-1 as the initial investigation because it reflects the average growth hormone output over time, rather than the pulsatile spikes that make random growth hormone measurements unreliable. The result is interpreted against an age- and sex-matched reference range — IGF-1 declines with age in healthy adults.

If IGF-1 is elevated (or normal but clinical suspicion is high), the confirmatory test is an oral glucose tolerance test with growth hormone measurement — a 75 g glucose drink is given and growth hormone is measured at baseline and at intervals over two hours. In health, growth hormone suppresses below 1.0 µg/L. Failure to suppress indicates autonomous growth hormone secretion consistent with acromegaly (Endocrine Society 2014).

MRI of the pituitary gland with gadolinium contrast (MBS item 63007/63010) identifies the adenoma, its size, and any extension towards the optic chiasm or cavernous sinuses. Most tumours are macroadenomas (>10 mm) at diagnosis due to the long diagnostic delay.

Associated comorbidity workup at diagnosis includes:

• Fasting glucose and HbA1c (type 2 diabetes in ~25–30% of patients)
• Blood pressure and ECG
• Echocardiogram (MBS item 55113) — hypertrophic cardiomyopathy assessment
• Sleep study (MBS items 12203/12204) — sleep apnoea in up to 70% of patients
• Colonoscopy (MBS item 32222) — colorectal polyp risk is elevated; colonoscopy at diagnosis is standard practice
• Prolactin — co-secretion in ~30% of growth-hormone-secreting adenomas
• Full pituitary hormone panel — thyroid, adrenal, and gonadal axes can be suppressed by the tumour mass

Formal visual field testing (Humphrey or Goldmann perimetry) is performed when the MRI shows proximity of the tumour to the optic chiasm.

Initial general practice role

A GP’s role is recognition and initiating the workup. Once IGF-1 is elevated and acromegaly is suspected, referral to an endocrinologist is appropriate and urgent — within two weeks where visual symptoms are present. The Endocrine Society of Australia can assist with appropriate specialist identification. Acromegaly is managed by a pituitary multidisciplinary team including endocrinology, neurosurgery, and radiation oncology at a tertiary centre.

B. Treatment and its outcomes

First-line: transsphenoidal surgery

Surgery to remove the pituitary adenoma through the nasal passages (endoscopic transsphenoidal surgery, or TSS) is the first-line treatment for most patients (Pituitary Society 2021). In experienced pituitary surgical units, biochemical cure rates approach 80% for microadenomas (tumours under 10 mm) and approximately 50% for macroadenomas. The main risk of surgery is hypopituitarism — damage to the surrounding pituitary tissue that requires lifelong hormone replacement.

Pre-operative anaesthetic assessment is important in acromegaly. The combination of macroglossia (enlarged tongue), enlarged lower jaw, and potential cardiomyopathy creates specific airway and cardiac management challenges.

Medical therapy for incomplete control or surgical failure

When surgery does not achieve full biochemical remission, or when patients are not surgical candidates, three medication classes are available:

Somatostatin receptor ligands (SRLs) — octreotide LAR and lanreotide — are long-acting injections given once monthly that suppress growth hormone secretion. They are first-line medical therapy, achieving IGF-1 normalisation in approximately 50–60% of patients and significant clinical improvement in most. Both are available on the PBS Authority Required for acromegaly. Pasireotide LAR is an alternative for patients who fail standard SRLs, though it carries a higher risk of hyperglycaemia.

Dopamine agonists — cabergoline in low oral doses — are useful when growth hormone elevation is modest, or when the adenoma co-secretes prolactin. Available PBS Authority for relevant indications and more convenient than injections.

Pegvisomant is a growth hormone receptor antagonist — it blocks the action of growth hormone rather than suppressing its secretion. It normalises IGF-1 in approximately 95% of patients (Endocrine Society 2014). The trade-offs are a daily subcutaneous injection requirement, higher cost, and the need for ongoing pituitary MRI monitoring since pegvisomant does not shrink the tumour. Available through the PBS Section 100 Highly Specialised Drugs Programme, Authority Required.

Radiotherapy for refractory disease

Stereotactic radiosurgery (Gamma Knife, CyberKnife) delivers focused radiation to the adenoma in a single or small number of sessions, with greater precision and lower risk of damage to surrounding tissue than conventional fractionated radiotherapy. It is used when surgery has not achieved cure and medication is inadequate or not tolerated. The biochemical response develops slowly — over 2–10 years — and hypopituitarism develops in 30–50% of patients over the same period, requiring ongoing hormone monitoring and replacement.

Goals of treatment

The 2024 consensus on acromegaly diagnosis and remission defines treatment success as: normalisation of IGF-1 for age and sex, plus a random growth hormone below 1.0 µg/L. With multimodal treatment, approximately 70–80% of patients achieve biochemical control. Symptoms that often improve include sweating, soft tissue swelling, fatigue, and carpal tunnel syndrome. Joint changes and bone enlargement that have developed over many years are generally not reversible.

C. Managing comorbidities — the general practice role

Once a patient is under specialist care for the acromegaly itself, general practice plays a central role in managing the associated health conditions:

Hypertension is present in approximately 35% of patients with acromegaly. Management follows standard RACGP hypertension guidance, typically with ACE inhibitor or angiotensin receptor blocker as first-line agents given the cardiac remodelling risk.

Type 2 diabetes and insulin resistance occur in 25–30% of patients. Metformin is appropriate first-line; GLP-1 receptor agonists offer additional benefit given their cardiovascular protection and weight effects. Note that pasireotide LAR (one of the SRL options used by endocrinologists) can worsen glycaemia significantly and requires close glucose monitoring during adjustment.

Sleep apnoea affects up to 70% of patients with acromegaly. A sleep study is part of the initial workup; CPAP therapy is the treatment and may need to be reassessed as soft tissue changes respond to acromegaly treatment — sometimes CPAP settings require revision after biochemical control is achieved.

Colorectal cancer surveillance — colonoscopy at diagnosis followed by five-yearly surveillance — is the standard approach given a roughly twofold increased risk of colorectal polyps. If polyps are found, more frequent surveillance applies per gastroenterology guidance.

Carpal tunnel syndrome in acromegaly often improves or resolves as growth hormone levels are controlled — referral for carpal tunnel release surgery is reasonable, but it is worth confirming biochemical control first before committing to surgery if the diagnosis is new.

Bone and joint health — acromegaly accelerates osteoarthritis and can cause vertebral fracture risk despite apparently normal bone density on DEXA. Vitamin D and calcium optimisation, appropriate analgesia, and physiotherapy are part of ongoing management.

D. Australian operations

Acromegaly is a specialist-managed condition. General practice initiates the diagnosis (IGF-1 test), manages comorbidities, and participates in shared-care follow-up.

MBS access:

• IGF-1 testing and OGTT-GH suppression are ordered through specialist endocrinology referral or can be initiated by a GP where clinical suspicion is clear
• MRI pituitary (items 63007/63010), echocardiogram (item 55113), polysomnography (items 12203/12204), and colonoscopy (item 32222) are all rebated under MBS

GPCCMP (MBS item 965) is appropriate for the comorbidities driven by acromegaly — type 2 diabetes, hypertension, sleep apnoea — enabling structured allied health referral to dietitian, diabetes educator, and exercise physiologist.

PBS access:

• Octreotide LAR and lanreotide — PBS Authority Required for acromegaly, initiated by specialist
• Pegvisomant (Somavert) — Section 100 Highly Specialised Drugs, specialist-initiated, continuing GP prescribing under shared care arrangement
• Cabergoline — PBS Authority Required

Patient support: Pituitary Foundation Australia provides peer support and patient education. Acromegaly Australia is an informal community group. HealthDirect and Better Health Channel have consumer-friendly overviews.

E. Special populations

Younger adults and gigantism. When excess growth hormone begins before the growth plates close (in childhood or adolescence), the result is gigantism — excessive height rather than acral enlargement. Gigantism is even rarer than adult acromegaly. Paediatric endocrinology input is essential; treatment principles are similar.

Familial and genetic syndromes. Acromegaly occurs rarely as part of Multiple Endocrine Neoplasia type 1 (MEN1 — parathyroid, pancreatic, and pituitary tumours), McCune-Albright syndrome, Carney complex, and familial isolated pituitary adenoma (FIPA, from AIP gene variants). A family history of pituitary disease, early-onset acromegaly (under 30), or associated features of these syndromes warrants clinical genetics referral.

Pregnancy. Acromegaly in pregnancy is rare and requires specialist obstetric endocrinology co-management. SRLs are generally suspended during pregnancy given limited safety data; close monitoring of tumour size and visual fields is essential in macroadenoma patients.

Older adults. In older patients where symptoms have been attributed to osteoarthritis, carpal tunnel, or normal ageing for many years, acromegaly may not be considered until complications become severe. The diagnostic workup is the same regardless of age; treatment decisions balance surgical risk against ongoing comorbidity burden in shared decision-making with the patient.

When to escalate

The following warrant urgent or semi-urgent specialist review:

• Suspected acromegaly — refer to endocrinology within two weeks of elevated IGF-1
• Visual symptoms (peripheral vision loss or diplopia) — same-day ophthalmology and neurosurgery review if there is concern about rapid chiasmal compression
• Severe sudden headache with acromegaly — pituitary apoplexy (haemorrhage or infarction into the tumour) is a neurosurgical emergency; Emergency Department immediately
• Severe sleep apnoea with cardiovascular decompensation — hospitalisation and urgent CPAP initiation
• Worsening glycaemic control or new severe hypertension during SRL or pasireotide therapy — endocrinology review to adjust treatment

What this article is and is not

This is general health information drawn from Therapeutic Guidelines (eTG), AMH, NPS MedicineWise, Endocrine Society Clinical Practice Guideline 2014, Pituitary Society 2021, and 2024 consensus on remission criteria. It is not personal medical advice and does not create a doctor–patient relationship. Acromegaly diagnosis and treatment decisions are made in consultation with an endocrinologist and pituitary multidisciplinary team.

For consumer information: Pituitary Foundation Australia, HealthDirect, Better Health Channel, Endocrine Society of Australia.

If you notice sudden vision changes, severe headache, or rapid deterioration of any symptom, seek emergency medical care without delay.

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Sources cited

1. Therapeutic Guidelines (eTG) — Endocrinology
2. Australian Medicines Handbook (AMH)
3. NPS MedicineWise
4. Endocrine Society of Australia (ESA)
5. HealthDirect — Acromegaly
6. Better Health Channel
7. Pituitary Foundation Australia
8. Endocrine Society — Acromegaly Clinical Practice Guideline (JCEM 2014)
9. Pituitary Society — Updated acromegaly management consensus (2021)
10. Consensus on acromegaly diagnosis and remission criteria (Pituitary 2024)