Laboratory Information

Learn more about testing for Acromegaly and how to read your results

About Hormones

There are several hormones associated with an Acromegaly diagnosis. You will hear your medical team refer to the following hormones often.

  • Adrenocorticotropic hormone (ACTH) is a hormone that plays an important role by stimulating the production of cortisol. Learn how this hormone affects many aspects of your health and how to keep it in balance.

  • Cortisol is often called the "stress hormone." Learn how this hormone affects many aspects of your health and how to keep it in balance.

  • Ghrelin is an important digestive hormone that controls appetite. Learn how this hormone affects many aspects of your health and how to keep it in balance.

  • Human growth hormone (GH) is a substance that controls your body's growth. GH is made by the pituitary gland, located at the base of the brain. GH helps children grow taller (also called linear growth), increases muscle mass, and decreases body fat.

  • IGF1 is the major mediator of the anabolic and growth-promoting effects of growth hormone (GH). IGF1 is transported by IGF-binding proteins, in particular insulin-like growth factor-binding protein 3 (IGFBP3), which also controls its bioavailability and half-life.

  • Prolactin, or luteotropin, is the hormone that helps mammals produce milk. Learn how this hormone affects many aspects of your health and how to keep it in balance.

  • Somatostatin is also called SS, SST or SOM. This growth hormone inhibitory hormone affects several areas of the body by hindering the secretion of other hormones. Learn how this hormone affects many aspects of your health and how to keep it in balance.

  • The thyroid gland releases triiodothyronine (T3) and thyroxine (T4). These hormones play an important role in regulation of your weight, energy levels, internal temperature, skin, hair, nail growth, and more. Learn how this hormone affects many aspects of your health and how to keep it in balance.

Test FAQs

Learn about what tests are conducted for diagnosis

  • The gold standard diagnostic test remains the oral glucose tolerance test with concomitant GH measurement. Therapy for acromegaly is targeted at decreasing GH and IGF-1 levels, ameliorating patients' symptoms and decreasing any local compressive effects of the pituitary adenoma

  • Other tests include visual tests to test peripheral vision, heart, sleeping patterns, bowel, and bones. You may be asked to fill in a questionnaire that aims to assess how having acromegaly affects the quality of your life.

    • Human growth hormone (HGH or GH)

    • Thyroid-stimulating hormone (TSH)

    • Prolactin

    • Adrenocorticotrophin hormone (ATCH)

    • Follicle-stimulating hormone (FSH)

    • luteinizing hormone (LH)

  • Growth hormone suppression test.

    This is the best method for confirming an acromegaly diagnosis. During this test, your GH blood level is measured both before and after you drink a preparation of sugar (glucose).

  • Your doctor may recommend an imaging test, such as magnetic resonance imaging (MRI) or computed tomography (CAT Scans), to help pinpoint the location and size of a tumor on your pituitary gland. If no pituitary tumors are seen, your doctor may order other imaging tests to look for nonpituitary tumors.

IGF-1 FAQs

Learn about what IGF-1 is and why it is important diagnosis

  • While the tumor makes growth hormone, its action and effect is dependent on production of IGF-I (insulin-like growth factor-one); Blood IGF-I is produced, primarily in the liver, in response to the amount of GH made by the pituitary gland. The blood IGF-I level is a reliable indicator of overall growth hormone production. Since blood growth hormone levels fluctuate every few minutes over 24 hours, a single growth hormone level is only a “snapshot” in time and does not reflect overall growth hormone production. The blood IGF-I level is the most reliable indicator of overall growth hormone production. A normal blood IGF-I level usually indicates remission or, in patients taking medication, control of acromegaly.

  • After you've fasted overnight, your doctor will take a blood sample to measure the IGF-1 level in your blood. An elevated IGF-1 level suggests acromegaly.

  • This test measures the amount of insulin-like growth factor-1 (IGF-1) in your blood. IGF-1 is a hormone found naturally in your blood. Its main job is to manage the effects of growth hormone (GH) in your body. Normal IGF-1 and GH functions include tissue and bone growth.

  • Elevated IGF-1 and GH may indicate acromegaly in adults. Increased levels of GH and IGF-1 are normal during puberty and pregnancy; during the latter, serum IGF-1 increases on average almost 2-fold. Otherwise, increased levels are most frequently due to pituitary tumors (usually benign).

  • Acromegaly results from persistent hypersecretion of growth hormone (GH). Excess GH stimulates hepatic secretion of insulin-like growth factor-1 (IGF-1), which causes most of the clinical manifestations of acromegaly.

  • According to a recent consensus statement on multidisci- plinary management of acromegaly IGF-1 values up to 1.2–1.3× ULN range may also be considered sufficient for control of acromegaly [12]. Basal GH levels are measured in the morning after fasting and are usually elevated in patients with acromegaly [8].

  • A somatomedin C test, also called an insulin-like growth factor-1 (or IGF-1) test, helps doctors evaluate whether a person is producing a normal amount of human growth hormone (hGH, or somatotropin).

  • Levels vary not only by age and sex and are not standard across the board. To learn more, visit
    https://www.pathology.med.umich.edu/handbook/#/details/855

  • Elevated serum IGFBP-3 and IGF-1 levels indicate a sustained overproduction of GH or excessive rhGH therapy. Endogenous GH excess is caused mostly by GH-secreting pituitary adenomas, resulting in gigantism, if acquired before epiphyseal closure, and in acromegaly thereafter.

    Source: https://www.mayocliniclabs.com/

  • Excess GH and IGF-1 can cause abnormal growth of the skeleton and other signs and symptoms characteristic of two rare conditions, gigantism and acromegaly, generally due to a pituitary adenoma, a slow-growing, often benign tumor. This causes the pituitary to release excess amounts of GH.

Imaging FAQs

Learn about what image tests are conducted and why these are important diagnosis

  • Magnetic resonance imaging is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body

  • A pituitary MRI (magnetic resonance imaging) is an imaging test that makes pictures of the pituitary gland (small gland in the brain that controls hormones and other glands in the body) and surrounding areas in the brain.

  • Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body. An MRI scanner is a large tube that contains powerful magnets. You lie inside the tube during the scan.

  • They are very helpful in looking at the brain and spinal cord and are considered to be the best way to find pituitary tumors of all types. MRI images are usually more detailed than those from CT scans (see below). They can show macroadenomas of the pituitary gland, as well as most microadenomas.

  • A CT scan or computed tomography scan is a medical imaging technique used in radiology to obtain detailed internal images of the body noninvasively for diagnostic purposes. The personnel that perform CT scans are called radiographers or radiology technologists.

  • Both types of scan have similar uses, but they produce images in different ways. A CT scan uses X-rays, whereas an MRI scan uses strong magnetic fields and radio waves. CT scans are more common and less expensive, but MRI scans produce more detailed images.

  • A significant difference between CT and MRI scans is that CT scans expose patients to ionizing radiation, while an MRI does not. The amount of radiation used during this test is higher than the amount used in an x-ray. Therefore, a CT scan slightly increases your risk of cancer.

GH FAQs

Learn about what GH is and why it is important diagnosis

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Other Lab Test FAQs

Learn about what GH is and why it is important diagnosis

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  • An elevated IGF-1 level may indicate acromegaly. Oral Glucose Tolerance Test (OGTT) Growth hormone levels and blood glucose levels are also connected. In someone without acromegaly, a higher blood glucose level usually causes the body to stop producing GH.

  • We suggest that in these patients a raised prolactin level may be due either to interference with the normal inhibitory control mechanism of prolactin by suprasellar extension or, more rarely, to secretion of both GH and prolactin by the tumor itself.

  • Its hormones help regulate important functions such as growth, metabolism, blood pressure and reproduction. Other possible causes of prolactin overproduction include medications, other types of pituitary tumors, an underactive thyroid gland, ongoing irritation to the chest, pregnancy and breast-feeding.

  • Prolactin is secreted from the pituitary gland in response to eating, mating, estrogen treatment, ovulation and nursing. It is secreted heavily in pulses in between these events. Prolactin plays an essential role in metabolism, regulation of the immune system and pancreatic development.

  • A visual field test measures how far the eye sees in any direction without moving and how sensitive the vision is in different parts of the visual field. This helps doctors to find certain types of injuries and disease, like glaucoma.

  • The most common visual field test uses a light spot that is repeatedly presented in different areas of your peripheral vision. Less common testing may be performed by a technician manually moving a target to map areas of damage.