GHRP-2 test offers a convenient, safe diagnostic for severe adult growth hormone deficiency
Background
The clinical syndrome of adult growth hormone deficiency (AGHD) was first widely recognized in the 1980s. Patients with AGHD typically present with abnormal body composition, dyslipidemia, insulin resistance, and a significantly impaired quality of life due to decreased psychological well-being. Historically, the gold standard for diagnosis has been the insulin tolerance test (ITT), which carries certain risks and can be inconvenient for both patients and clinicians. This has created a need for safer, more accessible diagnostic tools. The growth hormone releasing peptide-2 (GHRP-2) test has emerged as a promising alternative, particularly in Japan, where it is recommended for its convenience and safety profile.
Study Design
This paper reviews the clinical features, diagnosis, and treatment of adult growth hormone deficiency (AGHD). The authors describe the diagnostic criteria for severe AGHD in Japan using the growth hormone releasing peptide-2 (GHRP-2) test. The protocol involves administering GHRP-2 and measuring the subsequent peak GH concentration. The review also outlines the standard-of-care for GH replacement therapy, recommending an initial low dose of 3 µg/kg body weight/day, with individualized dose titration based on clinical response and serum insulin-like growth factor-I (IGF-I) levels.
Results
The international consensus guidelines recognize the insulin tolerance test (ITT) as the gold standard for diagnosing AGHD. However, in Japan, the GHRP-2 test is an available and recommended alternative due to its safety and convenience. For diagnosing severe AGHD, the established cut-off value using this test is a peak GH concentration below 9 µg/L. Following diagnosis, GH replacement therapy has been approved for Japanese patients with severe AGHD since 2006. This therapy has shown various favorable effects, including improvements in body composition, lipid profiles, and quality of life.
The review highlights that a peak GH concentration of 9 µg/L during the
GHRP-2 testis the diagnostic cut-off for severe adult growth hormone deficiency. Despite these positive outcomes, the authors note that a direct, definitive link between GH replacement therapy and a reduction in overall mortality has not yet been fully established.
Key Findings
- The growth hormone releasing peptide-2 (GHRP-2) test is a convenient and safe diagnostic for adult growth hormone deficiency (AGHD).
- A peak GH concentration of 9 µg/L during the GHRP-2 test is the diagnostic cut-off for severe AGHD.
- GH replacement therapy for adults should start at a low dose of 3 µg/kg body weight/day.
- Dose titration for GH therapy should be individualized by monitoring clinical status and serum IGF-I concentrations.
- A direct effect of GH treatment on reducing mortality has not yet been fully established.
Why It Matters
This review solidifies the role of the GHRP-2 test as a viable, safe, and convenient diagnostic tool for adult growth hormone deficiency, offering an alternative to the more cumbersome insulin tolerance test. For individuals using or considering GH-releasing peptides, this provides a specific, clinically validated protocol and biomarker threshold (peak GH < 9 µg/L) for assessing potential deficiency. The recommended starting dose of 3 µg/kg/day for GH therapy, followed by titration based on IGF-I levels, provides a clear, evidence-based dosing strategy. This emphasizes the importance of starting low and adjusting based on lab markers rather than using standardized, higher doses. While the benefits on quality of life are clear, the lack of definitive data on mortality reduction suggests that treatment goals should focus on symptom management and metabolic improvement rather than life extension.
ghrp-2
growth hormone
adult growth hormone deficiency
diagnostic test
hormone replacement therapy
review
