From the FDA Drug Label
The mean terminal t1/2 after intravenous administration of somatropin in healthy adult males is estimated to be 19.5 ± 3. 1 minutes. The FDA drug label does not answer the question.
From the Research
Growth hormone being undetectable in a blood test is not necessarily indicative of growth hormone deficiency, as growth hormone is secreted in pulses throughout the day, with levels often falling below detection limits between these pulses. However, if growth hormone remains undetectable during stimulation testing (such as insulin tolerance test or glucagon stimulation test), this could indicate growth hormone deficiency. Adults with growth hormone deficiency may experience increased body fat, decreased muscle mass, reduced bone density, fatigue, and impaired quality of life. Children may show poor growth velocity and short stature. Diagnosis typically requires both clinical assessment and biochemical confirmation, including measurement of insulin-like growth factor-1 (IGF-1) levels.
Key Points to Consider
- Growth hormone deficiency can be congenital or acquired, and may occur in isolation or in the setting of multiple pituitary hormone deficiency 1.
- Evaluation for growth hormone deficiency should be undertaken after testing and replacement of other pituitary hormone deficits, and should include stimulation testing to confirm the diagnosis 2.
- Treatment for confirmed growth hormone deficiency involves growth hormone replacement therapy, typically administered as daily subcutaneous injections, with starting doses usually 0.2-0.3 mg/day for adults, adjusted based on clinical response and IGF-1 levels 3.
- Regular monitoring of clinical response, IGF-1 levels, and potential side effects is essential during treatment, and may include adjustments to thyroid hormone replacement therapy, as growth hormone replacement can unmask central hypothyroidism in some patients 4.
Clinical Considerations
- The diagnosis of growth hormone deficiency requires a systematic approach, including clinical assessment, biochemical confirmation, and stimulation testing 2.
- Growth hormone replacement therapy can have benefits in body composition, exercise capacity, skeletal integrity, and quality of life measures, but may also have risks, such as fluid-related adverse effects, and requires careful evaluation of the benefits and risks specific to the individual 5.
- The management of growth hormone deficiency should be individualized, taking into account the patient's clinical context, including the presence of other pituitary hormone deficiencies, and the potential need for adjustments to other hormone replacement therapies 3.