Acromegaly

What it is

Acromegaly is a rare but serious hormonal disorder affecting an estimated 3 to 14 people per 100,000, in which the pituitary gland produces excess growth hormone (GH) during adulthood, causing abnormal widening of bones and enlargement of soft tissues — most visibly in the hands, feet, and face. Also called pituitary GH excess, acromegaly is distinct from gigantism, its childhood counterpart, because adult growth plates have already fused; bones cannot grow longer but do grow wider, producing the condition's characteristic physical changes. Most people are diagnosed in their 40s or 50s, but the average delay between first symptoms and diagnosis is 7 to 10 years — meaning many Canadians live with the condition for nearly a decade before it is identified. Left untreated, acromegaly significantly raises the risk of heart disease, type 2 diabetes, high blood pressure, and colorectal polyps.

In Canada, acromegaly is managed through endocrinology referral, with testing available at major hospital labs and commercial labs such as LifeLabs and Dynacare. There is no dedicated Canadian clinical guideline; Canadian endocrinologists follow the Endocrine Society's 2014 Clinical Practice Guideline as the primary reference standard.

Causes and mechanism

More than 95% of acromegaly cases are caused by a benign (non-cancerous) pituitary adenoma — a tumor on the pituitary gland at the base of the brain. The adenoma causes the pituitary to secrete far more GH than the body requires. Excess GH then signals the liver to produce insulin-like growth factor 1 (IGF-1), and it is IGF-1 that drives the physical changes: bone widening, soft-tissue growth, and the metabolic effects that raise cardiovascular and metabolic risk.

Less common causes include:

Cause	Frequency	Mechanism
Pituitary somatotroph adenoma	>95% of cases	Direct GH hypersecretion from pituitary tumor
Ectopic GHRH-secreting tumor	Rare	Lung, pancreas, or other organ tumor stimulates pituitary indirectly
Multiple endocrine neoplasia type 1 (MEN1)	Rare, inherited	Genetic syndrome causing pituitary and other endocrine tumors

In the vast majority of cases, the adenoma develops spontaneously with no identifiable family history or preventable risk factor.

Symptoms and diagnosis

Physical changes in acromegaly accumulate over years, which is why they are so often attributed to normal aging. The most common signs include:

• Gradual enlargement of hands and feet (patients often notice needing larger ring or shoe sizes)
• Coarsening of facial features: protruding jaw and brow, broader nose, wider tooth spacing
• Thickened, oily skin and skin tags
• Excessive sweating and body odour
• Joint pain and reduced range of motion
• Persistent headaches
• Fatigue and muscle weakness
• Carpal tunnel syndrome
• Sleep apnea
• Irregular or absent periods in women; reduced libido or erectile dysfunction in men

Diagnosis typically follows a three-step process:

1. IGF-1 blood test — the primary screening test; a consistently elevated IGF-1 for age and sex is the most reliable indicator and is available through LifeLabs and Dynacare across Canadian provinces.
2. Oral glucose tolerance test (OGTT) — in a healthy person, a glucose load suppresses GH below 1 ng/mL; in acromegaly, GH remains elevated, confirming autonomous secretion.
3. Pituitary MRI — confirms the presence, size, and location of the adenoma once biochemical diagnosis is established.

Additional investigations — echocardiogram, colonoscopy, sleep study, bone density scan — assess for complications that may already be present at diagnosis.

Treatment options

The goal of treatment is to normalize GH and IGF-1 levels, relieve tumor mass effects, and reduce the long-term risk of cardiovascular and metabolic complications.

Surgery is first-line for most patients. Transsphenoidal adenomectomy removes the tumor through the nose without external incision. For smaller tumors (microadenomas), surgery can normalize hormone levels immediately and is considered curative in a meaningful proportion of cases.

Medications are used when surgery does not fully normalize hormone levels or when surgery is not feasible:

• Somatostatin analogues (octreotide, lanreotide) — the main medical therapy; reduce GH secretion and can shrink tumor volume over time. Both are available in Canada and may be covered under provincial drug benefit programs or private insurance, though coverage criteria vary by province.
• Dopamine agonists (cabergoline) — used for milder biochemical elevation or in combination with somatostatin analogues.
• Pegvisomant — a GH receptor blocker used when somatostatin analogues have not achieved adequate IGF-1 control; does not shrink the tumor but effectively blocks downstream GH effects.

Radiation therapy is reserved for patients where surgery and medication have not achieved adequate control. Effects are gradual and may take several years to reach full benefit; hypopituitarism is a recognized long-term risk.

Ongoing monitoring of GH and IGF-1 levels is essential after any treatment, alongside regular screening for type 2 diabetes, hypertension, and colorectal polyps.

When to see a clinician in Canada

Speak with your family physician or nurse practitioner if you notice:

• A gradual increase in ring or shoe size without a change in overall weight
• Progressive changes in facial structure — jaw, brow, or nose appearing larger over time
• Persistent or worsening headaches, or any new changes in vision
• Joint pain or stiffness that is steadily worsening without a clear cause
• Sweating that seems disproportionate to your activity level
• Symptoms consistent with sleep apnea: loud snoring, waking unrefreshed

Because changes develop so slowly, they are easy to dismiss. If you or someone close to you has noticed a pattern building over time, it is worth raising with a clinician. An IGF-1 blood test is a straightforward first step that your family doctor can order. If acromegaly is suspected, referral to an endocrinologist is the standard pathway in Canada; wait times vary by province, and virtual endocrinology services through platforms such as Maple or Dialogue can help bridge access gaps in underserved regions.

Limitations and open questions

Research is still emerging on several aspects of acromegaly management. The optimal biochemical targets for "cure" after surgery remain debated — different expert groups use slightly different IGF-1 and GH thresholds to define remission. Long-term cardiovascular outcomes after successful biochemical control are not fully characterized, and it is unclear whether normalizing IGF-1 completely reverses the elevated cardiac risk. The role of newer somatostatin analogues (pasireotide) relative to first-generation agents is still being defined in head-to-head studies. Health Canada has not issued a standalone guidance document on acromegaly management, and provincial pharmacare coverage for pegvisomant and lanreotide varies considerably, creating access inequities across Canada that have not been systematically studied. The true prevalence of acromegaly in Canada is unknown, as no national registry exists.