23rd May 2025

Growth Hormone Deficiency in Adults

GH deficiency is a rare disorder caused by inadequate secretion of GH. It can be idiopathic, congenital or acquired. GH deficiency in adults is commonly due to pituitary tumour (78%), extra-pituitary tumour such as craniopharyngioma (13%) and unknown (8%). Therefore, it is important to test adults with known hypothalamic or pituitary disease, such as panhypopituitarism, for GH deficiency.

Clinical manifestations of GH deficiency 

• Reduced energy levels
• Reduced lean body mass 
• Increase in proportion of fat
• Reduced bone mineral density leading to osteoporosis
• Cardiovascular: increased LDL cholesterol, impaired cardiac function
• Insulin resistance,
• Poor quality of life and increased mortality

Diagnosis

• History of pituitary/hypothalamic disease or panhypopituitarism 
• Low serum IGF-1
• If IGF-1 levels are normal, a GHRH-Arginine simulation test can be done to diagnose. This involves taking a blood sample then injecting GHRH and then arginine over 30 minutes. Further blood samples are taken over the next two hours. Facial flushing is a common side effect of GHRH injection. A diagnosis is made if GH remains suppressed. The exact level depends on peak GH levels relative to patient’s BMI
• For further investigations, can consider pituitary imaging if not already completed

Management 

Treatment involves injections of recombinant human growth hormone (rHGH). Please note a positive simulation test is required to initiate treatment with rHGH in the National Health Service (NHS), UK.  Although patients taking this treatment are unlikely to have marked increases in their energy levels, it can improve muscle strength, bone mineral density, CVS risk factors and has some impact on quality of life