Growth Hormone Deficiency in Adults Treatment & Management

Updated: Nov 07, 2017
  • Author: Mohsen S Eledrisi, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Treatment

Medical Care

Growth hormone (GH) replacement therapy is provided in the form of human recombinant growth hormone. This is currently available in subcutaneous injection form. The starting dose of GH depends on the age and clinical condition of the patient. A dose regimen that is based on age along with dose titration has been associated with less adverse effects compared with a weight-based regimen. [37]  The following regimen is suggested [6] :

  • Age younger than 30 years: 0.4-0.5 mg/day (may be higher for patients transitioning from pediatric treatment)
  • Age 30-60 years: 0.2-0.3 mg/day
  • Age >60 years or those with diabetes mellitus or prediabetes: 0.1-0.2 mg/day

For patients with adherence issues, a less frequent dose regimen such as alternate days or 3 times per week using the same total weekly dosage can be used. [6]

Follow-up is usually planned at intervals of 1-2 months when the dose of GH can be adjusted by increments of 0.1-0.2 mg/day based on the clinical response, serum IGF-1 levels, and side effects. Longer time intervals and smaller dose increments are suggested for older patients.

Serum IGF-1 levels are the main determinant for adjusting the dose of GH. No studies are available to guide this decision. A commonly used target is the upper half of the normal range appropriate for age and sex, unless significant side effects develop. [34]

Once maintenance doses of GH are achieved, follow-up is provided at intervals of 6 months. Monitoring includes clinical evaluation, assessment of side effects, and measurement of serum IGF-1, fasting glucose, and lipid profile. Quality of life (QOL) is also assessed using standardized questionnaires. If the initial bone mineral density findings, measured by DXA scan, are abnormal, repeat testing at intervals of 2-3 years is recommended. [34]

No studies are available regarding the optimal length of GH replacement therapy. Patients with childhood GH deficiency who attained adult height and had persistent deficiency on retesting should continue to receive GH therapy. [34]

GH therapy can also be continued indefinitely if benefits such as significant improvement in quality of life and objective improvements in biochemistry and body composition are observed. If no objective or subjective benefits are seen after 1 year of treatment, discontinuation of GH therapy should be considered. [6]

Published data do not confirm an association between GH therapy and recurrence or regrowth of pituitary tumors or craniopharyngiomas. [38, 39, 40] However, because of the possible association between increased IGF-1 levels and the risk of malignancy, there has been a theoretical concern that GH therapy could lead to regrowth of malignancies. [41] Therefore, GH therapy is not recommended for use in patients with a previous history of malignancy or in the presence of active malignancy. [34, 6]

GH therapy may increase the activity of the cytochrome P-450 system and alter the clearance of some medications known to be metabolized by this system, such as corticosteroids, anticonvulsants, sex steroids, and cyclosporine. Therefore, monitoring is advised when such medications are used in patients receiving GH therapy.

The most common side effects of GH therapy are related to fluid retention and include paresthesias, joint stiffness, peripheral edema, arthralgia, myalgia, carpal tunnel syndrome, and increased blood pressure. Most of these adverse effects improve with dose reduction. Older age, higher BMI, and female gender confer higher risk of these complications. [42]

GH therapy is associated with a mild increase in both fasting serum glucose and fasting plasma insulin levels. [43] Patients with diabetes mellitus who receive GH therapy may require adjustment in their glucose-lowering medications.

Because GH therapy can decrease levels of serum free T4 and cortisol, regular monitoring of thyroid and adrenal function is recommended. Patients on concurrent thyroid or adrenal hormone replacement may need dose adjustments after starting GH therapy. Patients who have normal thyroid and adrenal function require monitoring of serum free T4 and assessment of the hypothalamic-pituitary-adrenal axis because GH therapy can unmask central hypothyroidism and hypoadrenalism. [44, 45]

Patients who are on testosterone-replacement therapy may require their GH doses to be decreased, because testosterone can potentiate GH action and exacerbate GH-induced adverse effects. [46]

Women who are taking oral estrogen replacement therapy usually need higher doses of GH, but those on transdermal estrogen preparations may not. [47]

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Consultations

Consult with an endocrinologist.

Consult with a neurosurgeon for evaluation of pituitary tumors.

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