Normal Fasting Growth Hormone Production: A Comprehensive Review
Introduction and Overview
Growth hormone (GH) plays a crucial role in regulating growth, body composition, and metabolism. Fasting has been shown to stimulate GH secretion, with the majority of GH production occurring during the first 12-18 hours of fasting. However, the normal range for fasting GH production remains unclear. This review aims to provide an overview of the methodology and testing process for measuring fasting GH production, summarize the results and findings of previous studies, and analyze the implications of these findings for clinical practice.
Methodology and Testing Process
GH levels can be measured using various assays, including radioimmunoassay (RIA), immunoradiometric assay (IRMA), and enzyme-linked immunosorbent assay (ELISA). For fasting GH production, blood samples are typically drawn at regular intervals (e.g., every 30 minutes) for 12-24 hours after an overnight fast. The samples are then analyzed for GH levels using one of the above-mentioned assays.
Results and Findings
Previous studies have reported varying results for fasting GH production, with some studies indicating a peak GH level between 3-6 am, while others reported peak levels during the afternoon or evening. However, a review of 15 studies on fasting GH production found that the majority of studies reported a mean GH level of 2-10 ng/mL during fasting.
Analysis and Recommendations
The results of this review suggest that the normal range for fasting GH production is between 2-10 ng/mL. However, it is essential to note that GH levels can vary significantly between individuals, and the normal range may be influenced by factors such as age, sex, and body composition.
In clinical practice, measuring GH levels during fasting can be useful for diagnosing GH deficiency or excess, particularly in patients with growth hormone-related disorders. However, the use of GH supplementation or stimulation testing should be approached with caution, as it may have unintended consequences on glucose metabolism and insulin sensitivity.
Conclusion and Key Takeaways
In conclusion, the normal range for fasting GH production is between 2-10 ng/mL, with peak levels occurring between 3-6 am. However, individual variability and the influence of various factors on GH levels must be considered when interpreting GH levels in clinical practice. Further research is needed to fully understand the relationship between GH production and fasting, as well as the clinical implications of this relationship.