Blood Tests For Hgh Deficiency: Types And Description
The blood test for growth hormone deficiency used by many doctors measures insulin growth factor 1 levels in the bloodstream. IGF-1 is a hormone produced by the liver. Because all hormones require a stimulus to aid in their secretion, we look to IGF-1 because growth hormone is what prompts the liver to release it. The IGF-1 test is beneficial because if growth hormone levels are low, the liver will not receive enough of a signal to produce insulin growth factor 1. As a result, IGF-1 levels, which remain stable in the bloodstream throughout the day, will decline.
It is essential to note that the doctor will not base the results of growth hormone deficiency testing solely on IGF-1 levels. Further down this page, we will discuss the other blood panels the doctor will order. The information provided by those tests helps the doctor to see if there are mitigating reasons why the pituitary gland is not producing enough growth hormone.
Here are some crucial facts to know about getting tested for growth hormone deficiency:
How Reliable Are Hgh Deficiency Tests
Growth hormone deficiency testing using IGF-1 levels is extremely reliable when assessed with the other blood tests listed below. Again, please remember that the tests are confirmation of the doctors suspicion of growth hormone deficiency due to the exhibited symptoms.
Some people may require further testing, which could include any of the following:
- GH Suppression Test to help the doctor determine if the pituitary gland produces too much growth hormone
- GH Stimulation Test to determine how much growth hormone the pituitary gland releases in response to stimulating efforts
- MRI or CT Scan if the doctor suspects that a tumor is present in the hypothalamus or pituitary gland, an MRI or CT Scan may be necessary to confirm the diagnosis
What Are The Complications Of Growth Hormone Deficiency
Left untreated, growth hormone deficiency in children may lead to short stature and delayed puberty.
Despite proper treatment, people with adult-onset growth hormone deficiency have an increased risk of heart disease and stroke. Healthy living, such as eating a balanced diet and participating in routine exercise, can help reduce this risk.
People with adult-onset GHD also have a higher risk of developing osteoporosis. Because of this, they have a higher risk of developing bone fractures from minor injuries or falls. To decrease these risks, its important to have a diet thats rich in calcium and to take vitamin D supplements, as recommended by your healthcare provider.
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What Are The Risk Factors For Growth Hormone Deficiency
Unfortunately, most cases of growth hormone deficiency arent preventable. Certain risk factors can increase you or your childs likelihood of developing acquired GHD, including:
- Cancer treatment before reaching adult height.
- Radiation to your head or brain.
- Total body irradiation.
- Surgery to your brain, especially the central region of your brain where your pituitary gland is located.
If any of these risk factors apply to you or your child, its important to talk to your healthcare provider about the signs and symptoms of GHD to look out for.
Low Growth Hormone Levels
Low levels of GH associated with low IGF-1 levels cause dwarfism in children and vague, nonspecific symptoms , along with increased risk of cardiovascular disease in adults.
Genetic causes of low GH levels include the following :
- Combined pituitary hormone deficiencies – HESX1, LHX3, LHX4, SOX3, GLI2, PROP1, PITX2, and PIT1 gene mutations
- Isolated GH deficiency – GH1, GHRH, and GHRHR gene mutations
Tumor-related causes of low GH levels include the following :
- Benign – Craniopharyngioma, arachnoid cyst, pituitary adenoma, Rathke cleft cyst
- Malignant – Dysgerminoma, meningioma, glioma, metastatic Hodgkin disease
Traumatic causes of low GH levels include the following :
- Surgical trauma
Inflammatory causes of low GH levels include the following :
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How To Understand The Results Meaning
The interpretation of test results should always be left up to a medical professional. One high or low reading can easily send a person to the computer to look up what is wrong with them. A hormone specialist understands how to look at the bigger picture. A diagnosis is not always based on one result or finding.
When undergoing growth hormone deficiency testing, it may be necessary to wait a day or two and repeat a test if an inaccuracy is suspect. Just because a person may have high or low IGF-1 levels does not mean he or she does or does not have a deficiency. The interpretation of the findings requires knowledge of the individuals medical history and current status, as shown in the health questionnaire and the physical examination report.
The interpretation of growth hormone deficiency testing results should be left to the hormone specialist who uses additional information from the health questionnaire and physical examination.
Treatment Of Growth Hormone Deficiency
Recombinant GH supplements
Sometimes other pituitary hormone replacement
Recombinant GH is indicated for all children with short stature who have documented growth hormone deficiency. Documented growth hormone deficiency is based on auxologic, biochemical, and sometimes radiologic findings.
Dosing of recombinant GH is usually from 0.03 to 0.05 mg/kg subcutaneously once a day. With therapy, height velocity often increases to 10 to 12 cm/year in the first year and, although it increases more slowly thereafter, remains above pretreatment rates. Therapy is continued until an acceptable height is reached or growth rate falls below 2.5 cm/year. A preparation of GH is available for patients with GH deficiency who are â¥ 1 year of age who weigh at least 11.5 kg. A typical starting dosage is 0.24 mg/kg subcutaneously once/week.
) should be replaced throughout childhood, adolescence, and adulthood when circulating levels of these hormones are low. Diabetes insipidus typically requires lifelong treatment with desmopressin in tablet or intranasal form due to a hypothalamic-pituitary disorder or from resistance of the kidneys… read more ). When puberty does not occur normally, treatment with gonadal sex steroids is indicated , luteinizing hormone, and follicle-stimulating… read more ).
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How Do We Test For Growth Hormone Levels
Since your growth hormone levels can and do change throughout the day, instead of a test that measures the HGH level in your blood at any given time, we test for the level of IGF-1.
IGF-1 is an endocrine hormone produced by the liver that, along with growth hormone, helps promote normal bone and tissue growth and development. The IGF-1 test is used:
- To help diagnose growth hormone deficiency
- To sometimes diagnose growth hormone excess
- To evaluate pituitary function
- To monitor the effectiveness of treatment
During the test a blood sample will be drawn from a vein in your arm. Since HGH levels fluctuate throughout the day, we do not test for HGH, but rather IGF-1. IGF-1 mirrors HGH excesses and deficiencies, but the level in the blood is stable throughout the day, making it a more useful indicator of average HGH levels than testing for HGH.
We use LabCorp for all of our hormone tests. LabCorp is one of the worlds most respected life sciences companies and medical testing facilities. You can learn more about IGF-1 and the IGF-1 test by visiting the LabCorp website.
What Is Growth Hormone
Growth hormone is one of several hormones produced by the pituitary gland in your brain. Its also known as human growth hormone or somatotropin.
GH plays a crucial role in human growth and development, especially in children and adolescents. GH levels that are higher or lower than they should be can lead to health problems in both children and adults.
If your doctor suspects that your body may be producing too much or too little GH, theyll typically start by ordering tests to measure the levels of GH in your blood. Identifying any issues related to GH will help your doctor make a diagnosis and determine the best course of treatment for you.
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Ask A Laboratory Scientist
This form enables patients to ask specific questions about lab tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. Please allow 2-3 business days for an email response from one of the volunteers on the Consumer Information Response Team.
What Do The Test Results Indicate
If the growth hormone levels do not rise during the GH stimulation test, it indicates a GH deficiency. The treatment for GH deficiency includes synthetic growth hormone injections given to the child every day at bedtime. The treatment is continued till the child reaches adult height. Most children benefit from the treatment and show an increase in the height of up to 4 inches in the first year of therapy. Early diagnosis and treatment are essential to attain expected growth and development.
Suppose the GH levels do not decrease during the GH suppression test if the patient has gigantism or acromegaly, the cause is a tumor in the pituitary that produces excess hormones. Surgical removal of the tumor is the indicated treatment. The doctor may suggest a combination of surgery, medications, and radiation in a few cases.
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Diagnosis Of Growth Hormone Deficiency
Because no single test is 100% effective in eliciting GH release , two GH provocation tests are done . GH levels generally peak 30 to 90 minutes after administration of insulin or the onset of arginine infusion, 30 to 120 minutes after levodopa, 60 to 90 minutes after clonidine, and 120 to 180 minutes after glucagon.
The GH response that is considered normal is somewhat arbitrary. Generally, any stimulated GH level > 10 ng/mL is sufficient to rule out classic GH deficiency. GH deficiency may be considered for responses < 10 ng/mL to two pharmacologic stimuli, but results must be interpreted in the context of auxologic data. Because of the arbitrary nature of thresholds for normal results on provocative GH tests, children with otherwise unexplained short stature and normal provocative GH test results may be considered to have GH deficiency if they meet most of the following criteria:
Height > 2.25 standard deviations below the mean for age or > 2 SD below the midparental height percentile
Growth velocity < 25th percentile for bone age
Bone age > 2 SD below the mean for age
Low serum insulin-like growth factor 1 and IGF binding protein type 3 levels
Other clinical features suggesting growth hormone deficiency
If diminished GH release is confirmed, tests of secretion of other pituitary hormones and hormones of their target peripheral endocrine glands along with pituitary imaging studies must be done if not done previously.
C Physiological Assessment Of Gh Secretion
Measurements of 24-h spontaneous GH profiles by Hoffman et al. demonstrated a significant overlap of IGHC values between normal and GH-deficient adults. One third of the matched young normal subjects aged less than 50 yr had IGHC values within the range of the GH-deficient patients. Thus, estimation of IGHC failed to discriminate satisfactorily between GHD and normality, and at least part of the failure was due to the number of normal and hypopituitary subjects with values that were below the limit of detection of the GH RIA .
Thus, the peak 24-h GH level but not the IGHC or the nadir GH level discriminated satisfactorily between GH-deficient subjects and controls however, the series contained only 10 GH-deficient patients and 10 controls . Furthermore, one could only determine the peak spontaneous GH level by performing a full 24-h GH profile! These physiological studies utilizing highly sensitive GH assays have the potential to advance our understanding of the factors that control tonic and pulsatile GH secretion. Nonetheless, they are unlikely to contribute significantly to the pragmatic need to define GHD biochemically in an individual patient.
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Normal Growth Hormone Levels By Age
Jennifer Osipoff, MD, a pediatric endocrinologist with Stony Brook Childrens Hospital, says that growth hormone is secreted from the pituitary gland mainly during sleep. Still, this secretion also occurs in small spurts throughout the day.
As such, a random GH level is not a clinically relevant value if assessing for growth hormone deficiency or excess, Osipoff said. Instead, endocrinologists will measure insulin-like growth factor 1 , a protein that is made in response to GH secretion.
Providers break passing levels down into two groups: pediatric patients under 18 and adult patients 18 and over.
GHD is rare, and it doesnt usually explain a childs short stature or slow growth. A child may have below-average height for many reasons, including simple genetics.
Slow growth is also common for children, especially right before puberty. Children with a GH deficiency often grow under 2 inches per year.
A healthcare professional may also recommend GH testing if they notice signs a childs body is producing too much GH. For example, this can happen with a rare condition known as gigantism, which causes the long bones, muscles, and organs to grow excessively in childhood.
Adult bodies rely on GH to maintain muscle mass and bone density and regulate metabolism.
Growth Hormone Stimulation Test Results As Predictors Of Recombinant Human Growth Hormone Treatment Outcomes: Preliminary Analysis Of The National Cooperative Growth Study Database
Reprint requests to Center for Pharmacokinetic and Pharmacodynamic Research, Nemours Children’s Clinic, 807 Nira St, Jacksonville, FL 32207.
George M. Bright, Joanne R. Julius, John Lima, Sandra L. Blethen Growth Hormone Stimulation Test Results as Predictors of Recombinant Human Growth Hormone Treatment Outcomes: Preliminary Analysis of the National Cooperative Growth Study Database. Pediatrics October 1999 104 : 10281031. 10.1542/peds.104.S5.1028
Peak Growth Hormone Cut Off
As recombinant growth hormone became more widely available, less stringent criteria for the diagnosis of GHD were implemented with increase in peak GH cut off levels. With the renewed interest in oral GH secretagogues, a reassessment of peak GH cut offs may be helpful. The studies by Bright et al. and Blum et al. suggest that a partially intact pituitary axis is needed for GH secretagogues to be effective . Individuals with moderate growth hormone deficiency who may respond to GH secretagogues need to be differentiated from those with severe growth hormone deficiency who require growth hormone therapy .
Traditionally, the interpretation of GH stimulation testing results was binary with the adherence to pass/fail diagnostic GH cutoffs. Perhaps, instead, the results should be interpreted on a continuum that spans severe GHD requiring GH therapy to moderate or provisional GHD for which alternative therapies and further monitoring of growth should be considered . There is increasing evidence supporting the need to revisit cutoffs for peak GH after stimulation based on the assay used to measure serum GH concentrations . Lower cutoffs for peak GH levels based on specific assays have been proposed. The establishment of method-specific clinical evidence-based GH cutoff limits would help ensure adequate clinical diagnoses.
Growth Hormone Stimulation Test
A growth hormone stimulation test is done to find out if the pituitary gland is releasing growth hormone into the bloodstream in the right amounts. The pituitary is a small gland in the brain.
For this test, your child will get medicines to stimulate the pituitary gland to release growth hormone. The medicines used are L-arginine and:
Your provider may also use a medicine called CortrosynTM to know about cortisol, a stress hormone, in the blood.
Samples of blood are then taken and sent to the laboratory to measure the amount of growth hormone.
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How Is Growth Hormone Deficiency Treated
Since the mid-1980s, synthetic growth hormones have been used with great success to treat children and adults. Before synthetic growth hormones, natural growth hormones from cadavers were used for treatment.
Growth hormone is given by injection, typically into the bodys fatty tissues, such as the back of the arms, thighs, or buttocks. Its most effective as a daily treatment.
Side effects are generally minor, but may include:
- redness at the injection site
- curving of the spine
In rare cases, long-term growth hormone injections may contribute to the development of diabetes, especially in people with a family history of that disease.
Treatment Of Growth Hormone Deficiency In Children
Recombinant GH supplements
Sometimes other pituitary hormone replacement
Recombinant GH is indicated for all children with short stature who have documented growth hormone deficiency. Dosing is usually from 0.03 to 0.05 mg/kg subcutaneously once a day. With therapy, height velocity often increases to 10 to 12 cm/year in the first year and, although it increases more slowly thereafter, remains above pretreatment rates. Therapy is continued until an acceptable height is reached or growth rate falls below 2.5 cm/year.
) should be replaced throughout childhood, adolescence, and adulthood when circulating levels of these hormones are low. Diabetes insipidus typically requires lifelong treatment with desmopressin in tablet or intranasal form due to a hypothalamic-pituitary disorder or from resistance of the kidneys read more ). When puberty fails to occur normally, treatment with gonadal sex steroids is indicated , luteinizing hormone, and follicle-stimulating read more ).
GH therapy in children with short stature due to therapeutic radiation of the pituitary gland for cancer carries a theoretic risk of causing cancer recurrence. However, studies have not shown a greater-than-expected incidence of new cancers or a greater recurrence rate. GH replacement can probably be safely instituted at least 1 year after the successful completion of anticancer therapy.
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Blood Testing For Growth Hormone Levels In Adults
- Growth Hormone Deficiency in adults can only be diagnosed using specialized blood tests.
- HGH levels can fluctuate greatly throughout the day, so rather than specifying an exact normal HGH level for adults, doctors speak in terms of a normal range.
- Instead of a test that measures the HGH level in your blood at any given time, to test for GHD in adults, we use a test called IGF-1.
Growth hormone is essential for normal growth in children. Growth hormone, also known as HGH, also plays a critical role in adults. Growth hormone in adults is responsible for your ability to burn fat and build muscle. It is also essential for immune health, sexual wellness, and many other bodily processes.
Growth hormone does decline as you age. Many men and women over 40 could be suffering from growth hormone deficiency, or GHD. In adults, GHD can lead to tiredness, weight gain, lack of energy and sexual health issues.
The only way to know if you have GHD is to have your growth hormone and preferably your IGF-1 levels tested.