How to Diagnose Acromegaly: A Comprehensive Guide to Symptoms, Testing, and Medical Evaluation

Understanding Acromegaly and Its Diagnostic Challenges

Acromegaly is a rare but serious hormonal disorder caused by the overproduction of growth hormone (GH), typically due to a benign tumor in the pituitary gland. Because symptoms develop gradually over years, diagnosis is often delayed—sometimes by as long as a decade. Early detection is crucial to prevent irreversible complications such as joint damage, cardiovascular disease, and diabetes. Recognizing the subtle yet progressive changes in physical appearance and bodily function plays a key role in initiating timely medical evaluation.

Common Clinical Signs and Physical Manifestations

Visible Changes in Appearance and Soft Tissue Growth

One of the hallmark features of acromegaly is the noticeable transformation in facial structure. Patients may observe a protruding jaw, enlarged nose, thickened lips, and increased spacing between teeth. These changes are often first noticed by family members or seen in old photographs. Additionally, soft tissues throughout the body thicken, leading to coarsening of the skin, excessive sweating (hyperhidrosis), and oily skin due to heightened sebaceous gland activity.

Limb and Organ Enlargement

Patients frequently report that their rings no longer fit or that they need larger shoe or hat sizes—a telltale sign of extremity enlargement. Fingers and toes become wider and more padded, especially at the tips. Internally, organs such as the heart, liver, and kidneys may also enlarge (visceromegaly), increasing the risk for hypertension, sleep apnea, and cardiac dysfunction.

Metabolic and Musculoskeletal Complications

Glucose intolerance and type 2 diabetes affect up to 50% of individuals with acromegaly due to GH's anti-insulin effects. Unexplained weight gain, fatigue, and elevated blood sugar levels should prompt further investigation. Joint pain and arthritis are also common, resulting from cartilage overgrowth and bone remodeling, particularly in the spine and large joints. Over time, this can lead to reduced mobility and chronic discomfort.

Definitive Laboratory Diagnosis: Hormonal Testing

Blood Tests for Growth Hormone and IGF-1

While clinical signs raise suspicion, laboratory confirmation is essential. The primary diagnostic markers include serum insulin-like growth factor-1 (IGF-1) and random growth hormone levels. IGF-1, produced in the liver in response to GH, remains elevated throughout the day and serves as a reliable indicator of chronic GH excess. An age-adjusted IGF-1 level above the normal range strongly supports the diagnosis.

The Oral Glucose Suppression Test (OGTT)

The gold standard for confirming acromegaly is the oral glucose tolerance test (OGTT). Normally, glucose intake suppresses GH secretion. In acromegaly, however, GH levels fail to drop appropriately—typically remaining above 1 µg/L after a 75-gram glucose load. This failure to suppress confirms autonomous GH production and solidifies the diagnosis.

Locating the Source: Imaging and Pituitary Evaluation

Pituitary MRI for Tumor Detection

Once biochemical diagnosis is established, the next step is localization. Magnetic resonance imaging (MRI) of the pituitary gland is used to identify the presence, size, and location of a pituitary adenoma. Most cases of acromegaly (over 95%) are caused by a GH-secreting macroadenoma or microadenoma. High-resolution MRI helps guide treatment planning, whether surgical, medical, or radiation-based.

Differentiating Secondary Causes

In rare instances, acromegaly-like symptoms may stem from ectopic GH or GHRH (growth hormone-releasing hormone) production by tumors outside the pituitary, such as in the lungs or pancreas. Additional imaging like CT scans or PET scans may be necessary if pituitary imaging appears normal.

Supportive Diagnostic Tools and Bone Health Assessment

Bone X-rays and dual-energy X-ray absorptiometry (DEXA) scans are often recommended to evaluate skeletal complications. Long bone radiographs may reveal thickened cortices and enlarged extremities, while DEXA testing assesses bone mineral density. Interestingly, despite increased bone size, many patients develop osteoporosis or osteopenia due to metabolic imbalances, making fracture risk an important consideration.

Why Early and Accurate Diagnosis Matters

Timely diagnosis not only improves quality of life but significantly reduces long-term morbidity and mortality. Left untreated, acromegaly increases the risk of premature death by 2–3 times, primarily due to cardiovascular and respiratory diseases. A multidisciplinary approach involving endocrinologists, neurosurgeons, and radiologists ensures comprehensive care and optimal outcomes.

By combining clinical awareness with advanced hormonal testing and imaging, healthcare providers can detect acromegaly earlier, initiate appropriate therapy, and help patients regain control over their health and well-being.