AGHD is a rare disorder associated with increased morbidity and mortality1,2
There are more than
adults with a growth hormone (GH)
deficiency diagnosis in the United States.1
Potential causes of AGHD
The most common causes of Adult Growth Hormone Deficiency (AGHD) in adults are damage to the hypothalamus or pituitary gland due to tumors, surgery, cranial radiation, or traumatic brain injury.3
Why it is critical to test for AGHD
If left undiagnosed, AGHD may lead to increased risk for premature mortality, significant morbidity, and multiple signs and symptoms, including4
- An increase in body fat1
- A decrease in muscle mass1
- Weakness and fatigue3
- An increased rate of fractures3
- Cardiovascular disease3
- Impaired psychological well-being such as isolation, anxiety, or depression1
The clinical findings of AGHD are nonspecific and usually of little diagnostic value.5
It can be difficult to measure GH because it is secreted episodically in a pulsatile pattern with peaks and troughs and is influenced by a number of factors, including age, gender, and body mass index. Approximately 65% of GH production occurs at night, activated by slow-wave sleep. Because trough secretion makes up more than half the day, GH secretion may be undetectable by routine testing.6,7
Measuring insulin-like growth factor 1 (IGF-1) is a standard assessment of GH function; however, 50% of patients with AGHD have IGF-1 levels within the normal reference range. At the same time, patients with a normal response to GH evaluation can show low IGF-1 levels.8,9
The landscape for AGHD testing
References: 1. Brod M, Pohlman B, Højbjerre L, Adalsteinsson JE, Rasmussen MH. Impact of adult growth hormone deficiency on daily functioning and well-being. BMC Res Notes. 2014;7:813. doi:10.1186/1756-0500-7-813. 2. Monson JP, Brooke AM, Akker S. Adult growth hormone deficiency. In: De Groot LJ, Chrousos G, Dungan K, et al, eds. Endotext [Internet]. South Dartmouth, MA: MDText.com, Inc.; 2000. Updated May 2015. 3. Agrawal V, Garcia JM. The macimorelin-stimulated growth hormone test for adult growth hormone deficiency diagnosis. Expert Rev Mol Diagn. 2014;14(6):647-654. 4. Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML; for the Endocrine Society. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96(6):1587-1609. 5. Boguszewski CL. Update on GH therapy in adults. F1000Research. 2017;6(F1000 Faculty Rev). doi:10.12688/f1000research.12057.1. 6. Yuen KC, Tritos NA, Samson SL, Hoffman AR, Katznelson L. American Association of Clinical Endocrinologists and American College of Endocrinology disease state clinical review: update on growth hormone stimulation testing and proposed reviewed cut-point for the glucagon stimulation test in the diagnosis of adult growth hormone deficiency. Endocr Pract. 2016;22(10):1235-1244. 7. Melmed S. Idiopathic adult growth hormone deficiency. J Clin Endocrinol Metab. 2013;98(6):2187-2197. 8. Kreber LA, Griesbach GS, Ashley MJ. Detection of growth hormone deficiency in adults with chronic traumatic brain injury. J Neurotrauma. 2016;33(17):1607-1613. 9. Lissett CA, Jönsson P, Monson JP, Shalet SM; KIMS International Board. Determinants of IGF-I status in a large cohort of growth hormone-deficient (GHD) subjects: the role of timing of onset of GHD. Clin Endocrinol (Oxf). 2003;59(6):773-778. 10. Yuen KCJ. Growth hormone stimulation tests in assessing adult growth hormone deficiency. In: De Groot LJ, Chrousos G, Dungan K, et al, eds. Endotext [Internet]. South Dartmouth, MA: MDText.com, Inc.; 2000. Updated August 2016. 11. Berg C, Meinel T, Lahner H, et al. Diagnostic utility of the glucagon stimulation test in comparison to the insulin tolerance test in patients following pituitary surgery. Eur J Endocrinol. 2010;162(3):477-482. 12. Leong KS, Walker AB, Martin I, Wile D, Wilding J, MacFarlane IA. An audit of 500 subcutaneous glucagon stimulation tests to assess growth hormone and ACTH secretion in patients with hypothalamic-pituitary disease. Clin Endocrinol (Oxf). 2001;54(4):463-468. 13. Macrilen [prescribing information]. Trevose, PA: Strongbridge U.S. Inc.; 2018.
Macrilen is indicated for the diagnosis of adult growth hormone deficiency (AGHD).
Limitations of Use
The safety and diagnostic performance of Macrilen have not been established for subjects with a body mass index (BMI) > 40 kg/m2.
Important Safety Information
Warnings and Precautions
Macrilen causes an increase of about 11 msec in the corrected QT (QTc) interval. QT prolongation can lead to development of torsade de pointes-type ventricular tachycardia with the risk increasing as the degree of prolongation increases. The concomitant use of Macrilen with drugs that are known to prolong the QT interval should be avoided.
Potential for False Positive Test Results with Use of Strong CYP3A4 Inducers
Concomitant use of strong CYP3A4 inducers with Macrilen can decrease macimorelin plasma levels significantly and thereby lead to a false positive result. Strong CYP3A4 inducers should be discontinued and enough time should be given to allow washout of CYP3A4 inducers prior to test administration.
Potential for False Negative Test Results in Recent Onset Hypothalamic Disease
Adult growth hormone (GH) deficiency caused by a hypothalamic lesion may not be detected early in the disease process. Macimorelin acts downstream from the hypothalamus and macimorelin stimulated release of stored GH reserves from the anterior pituitary could produce a false negative result early when the lesion involves the hypothalamus. Repeat testing may be warranted in this situation.
The most common adverse reactions were dysgeusia, dizziness, headache, fatigue, nausea, hunger, diarrhea, upper respiratory tract infection, feeling hot, hyperhidrosis, nasopharyngitis, and sinus bradycardia
Please see Full Prescribing Information.
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