Acromegaly/ Excess Growth Hormone

What is acromegaly?

Acromegaly is a hormonal disorder that develops when the pituitary gland, located at the base of the brain, produces excessive amounts of growth hormone (GH). The excess hormone stimulates the liver to release insulin-like growth factor 1 (IGF-1), leading to abnormal tissue growth throughout the body. Because this process occurs gradually, changes often go unnoticed for years before the condition is diagnosed.

In adults, acromegaly causes bones to thicken rather than lengthen, resulting in enlarged hands, feet and facial features. It can also lead to joint pain, sleep apnoea, diabetes and high blood pressure. When excess growth hormone occurs in childhood, before the growth plates have fused, the condition is called gigantism, leading to excessive height and rapid overall growth. If you look at the world’s tallest individuals, most had gigantism. 

Although acromegaly is rare, early recognition and treatment are vital to prevent long-term complications affecting the heart, metabolism and joints, and to improve quality of life.

What causes acromegaly?

Most cases of acromegaly are caused by a functional pituitary adenoma, a benign tumour that produces growth hormone.  This benign tumour arises from cells that normally produce GH, leading to continuous hormone secretion and overstimulation of tissue growth.

Other much rarer causes of Acromegaly: 

• Non-pituitary endocrine tumours — in rare cases, tumours located outside the pituitary gland, usually in the lungs, pancreas or adrenal glands, can produce growth hormone-releasing hormone (GHRH). This hormone stimulates the pituitary to release excess GH, producing similar effects to those of a pituitary adenoma.

• Genetic and familial factors — a small number of cases are linked to inherited syndromes such as multiple endocrine neoplasia type 1 (MEN1) or McCune–Albright syndrome, which predispose individuals to develop endocrine tumours and growth hormone excess.

Regardless of the underlying cause, persistent excess growth hormone leads to progressive tissue enlargement and metabolic disturbances. Identifying the source of hormone overproduction is essential for effective treatment and long-term management.

What are the symptoms of acromegaly?

The symptoms of acromegaly develop slowly over many years, making early recognition difficult as it is difficult to see the physical changes occur over time due to how gradually it occurs. They result from both the excessive growth hormone itself and the physical effects of a pituitary tumour pressing on nearby structures.

Physical changes

• Enlargement of the hands, feet and facial features (including the jaw, nose and brow)
• Skin tags
• Thickened skin and widened fingers or toes
• Coarse facial features and an enlarged tongue
• Dental spacing changes due to jaw enlargement
• Deepened voice and increased sweating

Musculoskeletal and soft tissue symptoms 

• Joint pain and stiffness from abnormal bone and cartilage growth
• Carpal tunnel syndrome, causing numbness and tingling in the hands
• Back pain and curvature of the spine (kyphosis)

Metabolic and general symptoms

• Fatigue and weakness
• Weight gain or changes in body composition
• Insulin resistance or type 2 diabetes
• High blood pressure and heart enlargement (cardiomegaly)
• Sleep apnoea due to airway narrowing

Symptoms from tumour pressure

• Headaches
• Visual disturbances, particularly loss of peripheral vision
• Occasionally, reduced pituitary function (hypopituitarism) affecting other hormones

Early diagnosis is crucial to prevent irreversible complications affecting the heart, joints, and metabolism.

Who is at risk of acromegaly in Singapore?

Acromegaly is a rare disorder that can occur in both men and women, typically between the ages of 30 and 50. While it can affect people of any age and is often sporadic, a small number of patients inherit genetic syndromes that increase the risk of pituitary or endocrine tumours, such as: 

• Multiple endocrine neoplasia type 1 (MEN1) — a hereditary condition causing tumours in the pituitary, pancreas, and parathyroid glands.

• McCune–Albright syndrome — a rare genetic disorder that can cause hormonal overactivity.

• Familial isolated pituitary adenoma (FIPA) — an inherited form of pituitary tumour that may produce growth hormone.

While the condition cannot always be prevented, early recognition of symptoms and regular monitoring in high-risk individuals allow for prompt diagnosis and effective treatment before complications develop.

What are the complications of acromegaly?

Without treatment, prolonged exposure to excess growth hormone and insulin-like growth factor 1 (IGF-1) can cause serious, sometimes irreversible complications affecting multiple organ systems. These complications are the main reason early diagnosis and treatment are so important.

Cardiovascular complications 

• Hypertension and heart enlargement (cardiomegaly) — the heart muscle thickens, which can lead to reduced heart function and heart failure if untreated.

• Irregular heart rhythms — arrhythmias are more common due to structural and metabolic changes in the heart. 

Metabolic and endocrine complications 

• Type 2 diabetes mellitus and insulin resistance — high levels of growth hormone interfere with insulin function, increasing blood sugar levels.

• Dyslipidaemia — altered fat metabolism may raise cholesterol and triglyceride levels.

Respiratory complications

• Sleep apnoea — enlargement of soft tissues in the throat can narrow airways, causing interrupted breathing during sleep.

Musculoskeletal and joint problems

• Arthropathy — joint damage and stiffness due to abnormal cartilage growth.

• Spinal deformities — enlargement of vertebrae can lead to back pain or curvature (kyphosis).

Neurological and visual effects 

• Headaches and visual field loss — large pituitary tumours can compress nearby nerves, particularly the optic chiasm.

Increased risk of certain cancers 

Some studies suggest that prolonged exposure to elevated IGF-1 may slightly increase the risk of colon and thyroid cancers.

Reduced quality of life and life expectancy 

If untreated, the cumulative effects of cardiovascular, metabolic and respiratory complications can shorten lifespan. With early and effective treatment, however, most patients achieve normal life expectancy and substantial symptom improvement.

How is acromegaly diagnosed?

Diagnosis of acromegaly requires careful clinical assessment supported by hormone testing and imaging studies. Because the condition develops slowly, early features may be subtle and several investigations are usually needed to confirm excess growth hormone production and identify its source.

Hormone testing

• Insulin-like growth factor 1 (IGF-1) — a raised IGF-1 level is the most reliable indicator of chronic growth hormone excess. Unlike GH itself, IGF-1 levels remain stable throughout the day, making this test highly useful for diagnosis.

• Oral glucose tolerance test (OGTT) — in healthy individuals, blood GH levels fall after drinking a glucose solution. In acromegaly, GH remains abnormally high despite glucose intake, confirming the diagnosis.

Imaging studies 

• Magnetic resonance imaging (MRI) — MRI of the pituitary gland is performed to detect a tumour and assess its size and position. MRI helps determine whether the tumour is confined to the gland or extending beyond it .

Additional investigations

• Visual field testing — may be carried out if the tumour is large or pressing on the optic nerves.

Screening for complications

• Screening tests — blood pressure, blood sugar, cholesterol and cardiac evaluations are often included to detect associated metabolic or cardiovascular effects.

Accurate diagnosis not only confirms the presence of acromegaly but also helps tailor treatment to control hormone levels, relieve pressure symptoms and prevent long-term complications.

What are the treatment options for acromegaly in Singapore?

The aim of treatment is to reduce growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels to normal, relieve pressure from the pituitary tumour and reverse or prevent complications. Treatment often combines surgery, medication and occasionally radiotherapy, depending on the tumour’s size, location and response to therapy.

Surgery

• Transsphenoidal surgery is usually the first treatment when a pituitary adenoma is the cause. The tumour is removed through the nasal passage without external incisions. If a tumour is found early, this offers a complete cure.

• Surgery can quickly reduce GH levels and relieve pressure on nearby structures such as the optic nerves.

• Outcomes depend on tumour size, as smaller tumours (microadenomas) are more likely to be completely removed, while larger ones (macroadenomas) may require additional medical therapy.

Medical therapy

When surgery is not possible or hormone levels remain elevated afterwards, medication is used to control GH production.

• Somatostatin analogues (such as octreotide or lanreotide) reduce GH secretion and can shrink the tumour over time.

• Dopamine agonists (such as cabergoline) may help lower GH and IGF-1 levels in some patients, particularly those with mixed prolactin and GH secretion.

• Growth hormone receptor antagonists (such as pegvisomant) block the effects of GH on body tissues, helping to normalise IGF-1 levels.

Radiotherapy  

• Radiotherapy may be recommended if surgery and medication fail to fully control hormone levels. 

• Modern techniques, such as stereotactic radiosurgery, deliver precise radiation to minimise damage to surrounding brain tissue. 

• Hormone levels fall gradually over months or years, so long-term monitoring is essential as other hormones may become deficient

Ongoing management

Regular follow-up with blood tests, MRI scans and evaluation for related conditions such as diabetes or heart disease ensures optimal control. Most patients require lifelong monitoring to maintain hormone balance and prevent recurrence.

With early diagnosis and appropriate treatment, acromegaly can be effectively managed, allowing patients to achieve normal hormone levels and an improved quality of life.

Prognosis and long-term outlook for acromegaly

With early diagnosis and effective treatment, most people with acromegaly can achieve normal or near-normal hormone levels and live healthy, active lives. The long-term outlook depends on how quickly the condition is recognised, the size of the pituitary tumour and how well growth hormone levels are controlled after treatment.

• Hormonal control and symptom improvement — successful treatment typically leads to a marked reduction in growth hormone and insulin-like growth factor 1 (IGF-1) levels. Many symptoms, such as fatigue, joint discomfort and soft tissue swelling, improve within months, although changes to bone structure are often permanent.

• Reversal of complications — metabolic issues such as diabetes, high blood pressure and sleep apnoea often improve with stable hormone control. Early treatment also reduces the risk of cardiovascular disease and extends life expectancy to that of the general population.

• Recurrence and long-term follow-up — regular monitoring through hormone testing and MRI scans is essential, as pituitary tumours can recur even years after initial treatment. Lifelong medical supervision helps maintain hormonal balance and promptly address any complications.

• Quality of life — with advances in surgical techniques, medical therapy and imaging, long-term outcomes for acromegaly have improved significantly. Most patients can expect restored energy levels, improved metabolic health and a good quality of life with continued care.

Summary

Acromegaly is a rare but serious hormonal disorder caused by prolonged overproduction of growth hormone, usually due to a benign pituitary tumour. The condition develops gradually, often going unnoticed until physical changes or related health problems appear. If left untreated, it can lead to significant complications affecting the heart, metabolism, joints and overall quality of life.

Modern diagnostic methods, including hormone testing and MRI scanning, allow for accurate and early detection. With appropriate treatment, whether through surgery, medication or targeted radiotherapy, hormone levels can be brought under control, symptoms reduced and long-term health outcomes greatly improved.

If a doctor suspects you have acromegaly or you are experiencing symptoms or signs, such as an unexpected diagnosis of diabetes, changes in facial appearance, enlarged hands or feet, headaches or joint pains in the hands, schedule a consultation with The Metabolic Clinic for a proper evaluation, personalised treatment and ongoing hormonal care.

Frequently Asked Questions (FAQs)