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Acromegaly With Normal Insulin-like Growth Factor I Levels
MEDICAL RUNNING HEAD IMAGES
Acromegaly With Normal Insulin-like Growth Factor I Levels BEVERTON MOXEY, MD, AND JON M. SWEET, MD Department of Internal Medicine, Carilion Health System, Roanoke, Va
A
68-year-old woman was admitted to the hospital with acute pansinusitis and sepsis. She had edematous hands and feet, frontal bossing, macrognathia, coarse facial features, and numerous skin tags in nonflexural areas. Computed tomography of the head confirmed sinusitis and revealed diffuse hyperostosis of the calvaria and a pituitary adenoma. Magnetic resonance imaging of the brain revealed a T1-weighted isointense pituitary mass (2 × 2 × 2 cm) extending into the suprasellar cistern and compressing the optic chiasm. Radiographs showed thickening of the phalanges with distal spade-shape deformity. The serum insulin-like growth factor I (IGF-I) and IGF-I binding protein 3 levels were normal on repeated assays. Serum growth hormone levels before and 60 and 120 minutes after administration of 100 g of oral glucose were 76.6 ng/mL, 74.4 ng/mL, and 62.1 ng/mL, respectively; levels greater than 2 ng/mL confirm acromegaly. Current algorithms for diagnosing acromegaly rely heavily on measurement of IGF-I,1 with normal values essentially excluding the diagnosis. However, IGF-I concentrations are decreased by several factors, including advancing age, female sex, estrogen deficiency, and acute illness, because it is a negative acute phase reactant.2 An oral glucose tolerance test should be performed if acromegaly is suspected despite normal levels of IGF-I and IGF-I binding protein 3. 1. Biochemical assessment and long-term monitoring in patients with acromegaly: statement from a joint consensus conference of The Growth Hormone Research Society and The Pituitary Society. J Clin Endocrinol Metab. 2004;89:3099-3102. 2. Gabay C, Kushner I. Acute-phase proteins and other systemic responses to inflammation [published correction appears in N Engl J Med. 1999;340:1376]. N Engl J Med. 1999;340:448-454. © 2006 Mayo Foundation for Medical Education and Research
238
Mayo Clin Proc.
•
February 2006;81(2):238
•
www.mayoclinicproceedings.com
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
Acromegaly With Normal Insulin-like Growth Factor I Levels BEVERTON MOXEY, MD, AND JON M. SWEET, MD Department of Internal Medicine, Carilion Health System, Roanoke, Va
A
68-year-old woman was admitted to the hospital with acute pansinusitis and sepsis. She had edematous hands and feet, frontal bossing, macrognathia, coarse facial features, and numerous skin tags in nonflexural areas. Computed tomography of the head confirmed sinusitis and revealed diffuse hyperostosis of the calvaria and a pituitary adenoma. Magnetic resonance imaging of the brain revealed a T1-weighted isointense pituitary mass (2 × 2 × 2 cm) extending into the suprasellar cistern and compressing the optic chiasm. Radiographs showed thickening of the phalanges with distal spade-shape deformity. The serum insulin-like growth factor I (IGF-I) and IGF-I binding protein 3 levels were normal on repeated assays. Serum growth hormone levels before and 60 and 120 minutes after administration of 100 g of oral glucose were 76.6 ng/mL, 74.4 ng/mL, and 62.1 ng/mL, respectively; levels greater than 2 ng/mL confirm acromegaly. Current algorithms for diagnosing acromegaly rely heavily on measurement of IGF-I,1 with normal values essentially excluding the diagnosis. However, IGF-I concentrations are decreased by several factors, including advancing age, female sex, estrogen deficiency, and acute illness, because it is a negative acute phase reactant.2 An oral glucose tolerance test should be performed if acromegaly is suspected despite normal levels of IGF-I and IGF-I binding protein 3. 1. Biochemical assessment and long-term monitoring in patients with acromegaly: statement from a joint consensus conference of The Growth Hormone Research Society and The Pituitary Society. J Clin Endocrinol Metab. 2004;89:3099-3102. 2. Gabay C, Kushner I. Acute-phase proteins and other systemic responses to inflammation [published correction appears in N Engl J Med. 1999;340:1376]. N Engl J Med. 1999;340:448-454. © 2006 Mayo Foundation for Medical Education and Research
238
Mayo Clin Proc.
•
February 2006;81(2):238
•
www.mayoclinicproceedings.com
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.