Growth Hormone Deficiency in Adults

Human growth hormone (HGH) is essential for growth in children and normal metabolism in adults. Unfortunately HGH levels tend to decline with age which is why adults may require special attention in regard to hormonal balance and metabolic health.

When the pituitary gland is not producing enough HGH, it leads to a condition called growth hormone deficiency (GHD). If you suspect that you have GHD, it is best to contact a medical doctor such as an endocrinologist.

GHD can lead to serious health problems including abdominal obesity, muscle wasting, high cholesterol, fatigue, sexual dysfunction, and osteoporosis. It is considered a rare disease that affects 1-3 per 10 000 people, mostly children. GH deficiency with onset later in life affects about 1 per 100 000 adults.

Why does growth hormone deficiency occur?

Growth hormone deficiency can be congenital (present since birth), acquired, or idiopathic.

Congenital GHD is caused by abnormalities, syndromes, or genetic disorders that affect the function of the pituitary gland. According to trials, some of the genes can be inherited so a small percentage of GHD runs in families.

Adult-onset growth hormone deficiency (AGHD) is usually acquired and rarely idiopathic. In the case of idiopathic GHD, there is no identifiable cause.

Acquired deficiency occurs when there is a specific cause that has led to the inability of the pituitary gland to produce HGH. Examples are:

• Adenomas (tumors)
• Pituitary apoplexy (infarction or hemorrhage)
• Brain-injury
• Infection or inflammation
• Medical treatment (surgery or radiation)

Scientific studies report that pituitary tumors are the most common cause of acquired GHD in adults, contributing to about 65% of all cases. Some genetic and hereditary factors may play a role in their formation, but the majority of pituitary tumors have unknown ethology. Thus, there is also no specific prevention against most AGHD cases.

Currently, there is no evidence to suggest that stress or other lifestyle factors may contribute to the development of HGH deficiency. However, there are cases where stress can trigger symptoms such as hypoglycemia in patients who already have severe GH deficiency.

HGH deficiency may also lead to small abnormalities in the immune function, but studies do not report any immunodeficiency in those affected by the condition.

Untreated GH deficiency leads to visceral obesity and unfavorable lipid status which can have long-term consequences on the cardiovascular system. Some trials report that AGHD patients have increased mortality due to circulatory diseases when compared to healthy controls.

What are the symptoms of AGHD?

One of the most typical signs of growth hormone deficiency in adults is the accumulation of fat around the abdomen. The change in fat distribution is accompanied by increased fat storage around the internal organs which is called visceral fat.

According to studies, visceral obesity is a major risk factor for cardiovascular problems

Besides, up to 45% of GHD patients experience unfavorable changes in their lipid profile such as high LDL (bad) cholesterol and low HDL (good) cholesterol. This further increases the risk for severe atherosclerosis and heart disease.

Another symptom of AGHD that usually accompanies a change in fat distribution is loss of muscle mass and strength. That’s due to the reduction in insulin-like growth factor 1 (IGF-1) levels, which is a mediator of HGH’s anabolic effects and normally protects against muscle wasting.

Patients with growth hormone deficiency symptoms tend to experience reduced endurance and lower energy levels. In combination with loss of muscle size and strength, it might become harder or even impossible to perform normal daily activities.

A symptom of growth hormone deficiency, such as a lack of energy and motivation, can also affect your sexual health. Affected patients often report a complete lack of sexual desire and libido. A small study suggests that the low levels of IGF-1 can even lead to erectile problems in men affected by HGH deficiency.

The changes in body composition, poor energy levels, inability to complete normal daily tasks and sexual problems lead to a significant reduction in the quality of life in GHD patients.

If GHD is left untreated, some of the symptoms may progress and lead to complications

For example, low levels of IGF-1 in GHD patients lead to bone loss. If left untreated, the condition can cause osteoporosis and related complications.

How to diagnose GHD in adults?

The diagnosis of GH deficiency begins with a medical exam by a specialist in endocrinology. If you have symptoms that might be caused by low HGH then your physician will assign your diagnostic tests.

Unfortunately, simply measuring GH levels does not suffice for an accurate diagnosis because of the specific pattern of normal growth hormone secretion.

The pituitary gland produces HGH in pulses which are followed by rapid descends in GH levels. Even in healthy individuals, growth hormone levels can be undetectable during a minimum.

IGF-1 is somewhat more useful as a measurement because it reflects the mean daily HGH levels

However, official recommendations highlight that even if IGF-1 levels are normal, the test is not accurate enough to rule out GHD.

For an accurate diagnosis, a specialist must use a medication such as insulin to stimulate a peak GH secretion and then evaluate whether your pituitary gland produces enough growth hormone.

The most widely used test is called Insulin Tolerance Test (ITT). It triggers HGH pulse by lowering blood sugar down to 2.2 mmol/l (40 mg/dl).

Insulin Tolerance Test should be done in the morning after you have fasted overnight and skipped your breakfast. You must be in a healthcare facility and under strict medical supervision throughout the whole process. Right before the test, the medical team will access your condition and perform an ECG.

ITT has several contraindications such as advanced age, adrenal insufficiency, heart problems, and epilepsy. If you have any of these conditions, then glucagon or growth hormone-releasing hormone (GHRH) can be used as alternative medications for the test.

During the ITT, the medical team will measure your GH levels multiple times. If you have an HGH peak above 7 ng/ml then your doctor can safely rule out GHD.

According to the latest clinical practice guidelines, the optimal diagnostic cut-offs are 5.1 ng/ml for the ITT and 4.1 ng/ml for the GHRH test. If your GH peak does not reach the cut-off value for the specific test, it indicates that you have GHD.

If you are diagnosed with GHD, you’ll get a prescription for HGH from the doctor to start the therapy to manage your symptoms of GHD.

How we treat adult growth hormone deficiency

Currently, the only effective and FDA-approved treatment of AGHD is the regular use of subcutaneous growth hormone injections. No other treatment option has been shown by scientific evidence as safe and effective in the management of GHD.

The injections contain recombinant human growth hormone (RHGH) called somatropin. It has an identical structure to the HGH naturally produced in the human body.

Due to its peptide structure, the hormone can’t be effectively absorbed through the skin or digestive system, thus rendering injections the only effective option to administer RHGH into the body. They are usually applied subcutaneously, daily in order to mimic the normal GH production in healthy individuals.

If the GHD is left untreated, your symptoms will persist or even worsen, leading to complications such as cardiovascular problems and osteoporosis.

Products marketed as natural remedies for low HGH are not effective in patients with GH deficiency. The pituitary gland in GHD patients is no longer able to produce growth hormone, so any form of stimulation would be ineffective to restore normal synthesis.

What are the effects of AGHD treatment?

HGH therapy can gradually improve all symptoms in patients with AGHD. The guidelines of the International Endocrine Society confirm that HGH injections can lead to improvements in:

• body composition
• exercise capacity
• skeletal integrity
• cardiovascular outcomes
• lipoprotein metabolism
• quality of life

On average, it takes at least 4 weeks of therapy before IGF-1 levels increase back to reference levels and there are any noticeable benefits. The first improvements include losing abdominal and visceral fat while simultaneously preserving muscle tissue and increasing lean body mass.

Energy levels, cholesterol, and quality of life improve in the first 6 months. After this period, bone mineral density also starts to increase.

The time it takes until there are results of HGH therapy will depend on multiple factors including your individual characteristics and sensitivity as well as your doctor finding the optimal dose.

An experienced medical specialist should regularly monitor your treatment to maximize the benefits and reduce the risk of side effects.