Insulin-like Growth Factor-binding Protein 3 (IGFBP-3)
Approximately 95% of IGF-1 and IGF-II are bound to IGFBP-3, which makes this protein the major carrier of the insulin-like growth factors in circulation. The function of the binding protein is to extend the half-life of the growth factors in the circulation.
insulin-Like Growth Factor-Binding Protein 3 (IGFBP-3) - Everything You Need to Know
The growth hormone is one of the most important substances in the human body. It usually pairs well with IGF-1 and other hormones to grow cells, tissues, and muscles. However, some of these hormones need to be transported throughout the entire body and this is where IGFBP-3 comes into play.
Insulin-like growth factor-binding protein 3 is helping IGF-1 and other hormones to travel through the bloodstream and reach tissues, muscles, and organs. Keep reading to find out more about it and why you should order an IGFBP-3 test soon.
What Exactly is IGFBP-3?
As mentioned earlier, IGFBP-3 carries IGF-1 and IGF-2 through the bloodstream. This is a protein produced by the liver that extends the half-life of insulin-like growth factors and helps them reach target destinations such as other cells and tissues.
There are 6 types of protein carriers that pair with IGF-1 and IGF-2. These are IGFBP-1 to IGFBP-6 and IGFBP-3 is the most abundant. Almost all IGF-1 and IGF-2 bind to IGFBP-3 and use it to circulate freely throughout the bloodstream.
That's why doctors usually recommend doing an IGFBP-3 test alongside a growth hormone or IGF-1 test. It's important to see the full picture to diagnose pituitary gland problems or a human growth hormone deficiency.
What Are the Normal Values of IGFBP-3?
You already know that the levels of IGF-1 and growth hormone vary depending on your age, fitness level, lifestyle, and other factors. Similarly, IGFBP-3 levels also depend on these factors and they peak at certain age intervals for both men and women.
For example, normal levels of IGBP-3 vary between 0.5 mcg/mL and 7.2 mcg/mL. This happens as one grows from 1 year old to 20 years old. The highest numbers are seen as you get close to being 18-20 years of age. At this time, the IGFBP-3 is between 3.4 and 7.2 mcg/mL of blood.
These normal values stay elevated between 3.4 and 7.2 mcg/mL until you reach the age of 60. That's when they start to drop and eventually get to around 2.5-5 mcg/mL when you're in your eighties. These values are slightly lower for women.
If you do a test and your results don't fit the normal ranges, chances are that you're deficient in IGF-1 and/or growth hormone as well. More tests might be needed to see why this happens and whether your pituitary is the culprit.
Keep in mind that the pituitary is responsible for producing growth hormones throughout your entire lifetime. Problems related to this gland such as tumors might interfere with the pulsatile production of growth hormone. In this case, doctors might recommend a pituitary test as well.
Symptoms of Having Abnormal IGFBP-3 Values
Remember that IGF-1 and other hormones are carried by IGFBP-3 to reach various cells and organs. In most cases, if your IGF-1 levels are abnormal, your IGFBP-3 levels are also out of balance. That's why most patients who experience excessively low or high IGFBP-3 levels, their symptoms are similar to having IGF-1 deficiency.
Many of these symptoms are seen in children, but adults also experience symptoms that might disrupt the quality of their lives. For example, here are the most common symptoms for having low IGFBP-3 levels.
- Chronic fatigue, even after a good night's sleep
- Anxiety and depression
- Fragile bones
- Dry skin and brittle nails
- Losing or gaining weight without an obvious reason
In children, a lack of sufficient IGFBP-3 is usually associated with short stature, slowed growth rate, and delayed puberty. This can be seen in both boys and girls. Other symptoms include thinning hair, dry skin, and brittle nails.
Too much IGFBP-3 is rarely encountered and it's usually associated with acromegaly and/or gigantism in children. Adults who experience too much IGFBP-3 might also have high levels of growth hormone and IGF-1. Their symptoms include:
- Enlarged tongue
- Erectile dysfunction
- Chronic weakness
- Impaired muscle growth
- Anxiety and depression
Having too much IGFBP-3 and/or IGF-1 is not necessarily a good thing. That's why you should test for this hormone and see how you stand, especially if you experience some of the symptoms mentioned above.
How Is the Testing Procedure Done?
Testing your IGFBP-3 levels can be done very easily using a single blood sample. Doctors usually ask for this test if you experience growth hormone or IGF-1 deficiency.
It's necessary to stop biotin intake for at least 72 hours before doing the test. This substance might interfere with test results and you won't receive an accurate diagnosis. If your IGFBP-3 levels are out of balance, your doctor might recommend additional tests such as IGF-1, growth hormone, or pituitary tests.
The result of the test should come back to you via email in just a few business days. Once you have them, you can compare your results against reference values and see how you stand. Your primary healthcare provider might also help you interpret the results correctly.
Order Your IGFBP-3 Test Today!
As you can see, being deficient in IGFBP-3 can result in fatigue, impaired muscle development, and other health issues. That's because your body doesn't have enough protein carriers to move IGF-1 around or you struggle with a growth hormone/IGF-1 deficiency.
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