Objectifying Acral Enlargement in Acromegaly
Acral enlargement is objectified through clinical history of increasing shoe, glove, or hat size combined with physical examination findings of large hands and feet with frontal bossing, followed by biochemical confirmation with serum growth hormone ≥1 ng/mL during oral glucose load and elevated age- and sex-matched IGF-1 levels, with MRI of the pituitary for anatomic confirmation. 1
Clinical History Documentation
The most practical way to objectify acral enlargement is through serial documentation of:
- Progressive increase in shoe size over time 1
- Progressive increase in glove size 1
- Progressive increase in hat size 1
These objective measurements provide quantifiable evidence of acral growth that patients can typically recall with specific timeframes (e.g., "went from size 9 to size 11 shoes over 5 years"). 2
Physical Examination Findings
On examination, acral enlargement manifests as:
- Large hands and feet that appear disproportionate to body habitus 1
- Frontal bossing (prominent forehead) 1
- Prognathism (protruding lower jaw) 2
- Coarse facial features 2
- Thickened, rough skin texture 2
The physical examination provides immediate visual and tactile confirmation of acral changes. 3, 4
Biochemical Confirmation (Screening Tests)
Initial screening involves:
- Serum growth hormone level ≥1 ng/mL during oral glucose tolerance test (normally GH should suppress to <1 ng/mL) 1
This screening test has high sensitivity for detecting active acromegaly when clinical features are present. 3, 4
Biochemical Confirmation (Confirmatory Tests)
Definitive biochemical confirmation requires:
- Elevated age- and sex-matched IGF-1 level (the most reliable single test) 1
- Failure of GH suppression below 1 ng/mL during oral glucose tolerance test 2
IGF-1 levels are considered the gold standard for diagnosis as they reflect integrated GH secretion over 24 hours and are less subject to fluctuation than random GH measurements. 3, 4
Anatomic Confirmation
MRI scan of the pituitary gland is performed to identify the somatotroph adenoma causing GH hypersecretion. 1
Modern MRI techniques can visualize even small pituitary tumors that were previously undetectable, improving diagnostic accuracy. 3, 4
Additional Objective Measurements
Heel pad thickness measurement can provide additional objective evidence, with increased heel pad size supporting the diagnosis. 2
Radiographic assessment of sella turcica enlargement on skull X-ray may show enlargement in all diameters, though MRI has largely replaced this modality. 2
Common Pitfalls to Avoid
Do not rely on random GH measurements alone, as GH secretion is pulsatile and a single normal value does not exclude acromegaly. 3, 4
Do not overlook the importance of age- and sex-matched IGF-1 reference ranges, as normal values vary significantly with age and using inappropriate reference ranges leads to misdiagnosis. 3, 4
Do not delay diagnosis based on subtle findings—acromegaly typically takes 7-10 years from symptom onset to diagnosis because changes occur gradually, and early recognition based on objective measurements of shoe/glove/hat size changes is critical for reducing morbidity and mortality. 3, 4