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ANSWER SOME QUESTIONS ON IGF1
DIR By: Road2HardCoreIron
Date: December 10, 2022, 6:35 pm
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Insulin-like Growth Factor 1, also known as IGF-1, is used as a
biomarker for blood levels of human growth hormone. The blood
level of IGF-1 appears to fluctuate over 24 hours and is found
to be related to growth hormone secretion, hunger, sleep and
exercise.
It is a hormone produced by the liver and other tissues which
affects growth-promoting activities and glucose metabolism.
Because IGF-1 is related to the production and secretion of
growth hormone (HGH), physicians may use this measurement to
assess growth hormone status.
IGF-1, What is it?
IGF-1 is a hormone produced in our body that is structurally
very similar to insulin. It has an important role in growth
during childhood and in adulthood, continues to have anabolic
effects. IGF-1 is the main mediator of the effects of growth
hormone, which, most of us know, can benefit male physique
drastically and also has anti-aging effects.
What is the Relationship Between IGF-1 and GH?
As stated previously, IGF-1 is the primary mediator of GH
secretion. So what exactly does that mean? It all starts in an
area of the brain called the hypothalamus. Whenever GH needs to
be secreted (GH levels are typically highest during periods of
fasting and sleep) the hypothalamus releases growth
hormone-releasing hormone (GHRH). This GHRH then binds to
receptors in another area of the brain called the anterior
pituitary. The anterior pituitary then releases GH into the
bloodstream. GH has several effects on the body including a
glucose sparing effect- meaning that instead of the body
utilizing glucose as a primary energy source, the body taps into
adipose tissue, using stored fat as energy. In this regard, GH
can significantly help to burn. However, this is not the only
favorable action of GH. GH also has several anabolic growth
effects. It increases the uptake of amino acids from the blood
and increases protein synthesis in skeletal muscle tissue. This
anabolism however, can be come problematic due to the fact that
GH also targets bone cells and just about every other cell in
the body.
Excessive GH use can lead to a condition called acromegaly,
which is characterized by uncontrolled bone growth. The most
noticeable feature of someone with acromegaly or HGH abuse is
the development of a jagged/uncharacteristically large jawline.
Some oncologist fear that increased IGF-1 may accelerate certain
cancers, but studies on this subject are contradictory.
Where does IGF-1 come into play?
GH acts directly on the liver to produce IGF-1
This IGF-1 is then released into the blood stream to further
stimulate the growth effects of GH. These two hormones work
synergistically to promote cellular growth effects to the bone
cells, muscle cells, nervous system cells, immune cells, and
just about every cell in our body. GH also has a “diabetogenic
effect”, meaning that when GH binds to receptors on the liver,
the liver is instructed to break down glycogen into glucose,
which fuels growth effects.
Other benefits and effects of IGF-1
Interestingly enough, elevated IGF-1 levels (from elevated GH
levels) may potentially have a beneficial effect on erectile
dysfunction [1]. In 2011 a paper titled “IGF-1 levels are
significantly correlated with patient-reported measures of
sexual function” Growth hormone (GH) supplementation may help to
preserve erectile function. Researchers assessed whether serum
insulin-like growth factor 1 (IGF-1) levels, a surrogate for GH
levels, correlated with sexual function scores in 65 men who
completed the Sexual Health Inventory for Men (SHIM) and
Expanded Prostate Cancer Index Composite (EPIC) questionnaires,
and had serum IGF-1 and testosterone levels determined.
Median±s.d. IGF-1 level, SHIM and EPIC scores were 235.0±86.4,
19.5±8.7 and 56.4±28.3 mg ml−1, respectively. IGF-1 levels
and total SHIM score correlate significantly (r=0.31, P=0.02),
as do IGF-1 levels and all individual SHIM question scores, and
IGF-1 levels and the sexual domain of the EPIC questionnaire
(r=0.30, P=0.02)
The second figure below represents the total Sexual Health
Inventory for Men (SHIM) score vs serum insulin-like growth
factor (IGF-1) level. All subjects' IGF-1 levels plotted against
their self-reported scores of sexual function based on total
SHIM score. There is a statistically significant correlation
between the two measured values, (Spearman's correlation
coefficient, r=0.31; P=0.02).
Another study published titled “Men with high levels of anabolic
hormones less likely to develop worsening frailty” Proved that
having higher baseline levels of vitamin D, insulin-like growth
factor-1 (IGF-1) and its binding protein 3 (IGFBP3) was
associated with a lower risk of worse frailty status four years
later [2]. "Vitamin D, besides maintaining bone health,
regulates muscle function, and low vitamin D levels are linked
to lower muscle mass and strength. IGF-1 affects muscle growth
and repair, and its action and levels are modified by its
carrier protein IGFBP3," Swiecicka said.
Also linked to a lower likelihood of frailty status worsening
were higher baseline levels of the hormone
dehydroepiandrosterone sulfate (DHEA-S), but only in the oldest
men. Several potential pathways could link DHEA-S with frailty.
Swiecicka said, "DHEA-S may have direct anabolic effect on
muscle, and, more recently, its neuroprotective and immune
system-modulating effects have been described."
Products that naturally raise IGF-1 levels
How might we safely raise GH and IGF-1 levels? There are two
types of drugs that can safely raise GH and IGF-1 levels without
greatly exceeding normal physiological levels (the higher we
exceed normal physiological levels the greater the risk for
unwanted pathology such as acromegaly and enlarged organs).
These two types of drugs are:
1. Growth Hormone Secretagogues
2. Growth Hormone Releasing Hormone Mimetics
Growth Hormone Secretagogues (GHS)
GHSs are typically sequences of connected peptides (called
Growth Hormone Releasing Peptides) that bind to the GHS
receptor[3]. These receptors are present in many areas of the
body, but of importance, in the hypothalamus and anterior
pituitary, the areas responsible for GH release. The natural
ligand to the GHS receptor in the body is ghrelin, the hormone
responsible for sensing hunger and speeding up gastric emptying.
This is why when GHRP-6 is administered subcutaneously, the
patient will often report voracious hunger. This effect may be
beneficial to those who have trouble consuming enough food to
gain weight and muscle mass. Not only does this drug induce
hunger but it causes a large but very shortly sustained release
in GH. Typically this GH “spike” only lasts about 4 hours
(GHRP-6 has a very short half-life in the body). This short
duration disallows a proportional IGF-1 response from the liver.
This problem was solved with the invention of Ibutamoren.
Ibutamoren is a non-peptidic compound (vs peptidic GHRPs) that
binds to the GHS receptor.
Ibutamoren, as a ligand, acts directly on arcuate neurons of
hypothalamus to stimulate the release of GHRH. Activation of
these neurons by ibutamoren can be inhibited by sst
(somatostatin) or pretreatment with GH (IGF-1 Feedback
inhibition) [3].
An initial dose of ibutamoren causes a large spike in growth
hormone levels (following normal physiologic pulsatile
secretion) along with a large spike in cortisol. Subsequent and
continued daily administration causes (comparatively) much
smaller spikes in GH. IGF-1 levels become and stay elevated
without a cortisol spike. If a dose is missed within 24 hours
(half life of ibutamoren is 24 hours), IGF-1 will drop due to
decreased liver stimulation from GH output. GHRH secretion is
slowed by the continuously higher IGF-1 concentration, creating
a safe negative feedback loop [3]. GHRPs DO NOT have a negative
feedback loop because the GH spike is not sustained long enough
(due to a short 4 hour half life) to allow for a sustained
increase in IGF-1 (unless taken every few hours over a couple of
days) GHRPs also do not allow for normal physiologic pulsatile
function (which ibutamoren mimics). This negative feedback loop
makes ibutamoren relatively very safe when compared to exogenous
GH administration.
Growth Hormone Releasing Hormone Mimetics
These peptides mimic the hormone GHRH. GHRH is released from the
hypothalamus and it binds to receptors on the anterior
pituitary. The anterior pituitary then releases growth hormone
into the bloodstream. The most popular GHRH mimetic is
Sermorelin. It binds to the GHRH receptors of the hypothalamus
and causes a marked increase in GH levels and IGF-1 levels.
Notice that GH Secretagogues bind to the GHS receptor and GHRH
mimetics bind to the GHRH receptor. This means that there are
two different pathways used to increase natural GH and IGF-1
production. If a GHRH mimetic is used along with a GHS, the
synergistic effect should markedly increase natural GH and IGF-1
production.
IGF-1 in Relation to Testosterone
In a study titled “Testosterone administration increases
insulin-like growth factor-I levels in normal men.” Researchers
discovered just that [4]. Although testosterone (T)
administration can increase insulin-like growth factor-I (IGF-I)
when administered to hypogonadal men, no studies have examined
whether this occurs in normal men. The present study was
undertaken to determine if an increase in IGF-I may be part of
the anabolic effect of androgens. Researchers enrolled 11 normal
men in a randomized, double-blinded cross-over study. Subjects
were assigned to receive either T enanthate (TE) (300 mg im,
each week) or nandrolone (ND) decanoate (300 mg im, each week)
for 6 weeks. After a washout period subjects were administered
the alternate treatment. Pre- and posttreatment serum was
analyzed for IGF-I by RIA after acid-ethanol extraction.
Although GH levels were not significantly different after either
TE or ND treatment, they tended to increase after TE treatment
(1.23 +/- 0.28 ng/mL vs. 3.3 +/- 1.03 ng/mL) but remained
unchanged after ND treatment (1.68 +/- 0.68 ng/mL vs. 1.89 +/-
0.64 ng/mL). Serum total T levels increased 32 +/- 0.05 nmol/L
in the TE-treated men, but fell by 7 +/- 0.02 nmol/L in the
ND-treated men (P < 0.0001). These data indicate that when
normal men are given TE, serum IGF-I levels increase after 6
weeks of treatment.
IGF-1 Blood Test: Everything You Need to Know
IGF-1 stands for insulin-like growth factor. It's an essential
hormone in the human body, and it's very similar to the insulin
produced by your pancreas. An IGF-1 blood test is increasingly
popular these days since this hormone plays a significant role
in the numerous metabolic processes of the body.
But when was the last time you did an IGF-1 blood test? And why
should you do one? Keep reading this article to learn everything
you need to know about IGF-1 and its importance for human
health.
What Is an IGF-1 Blood Test?
IGF-1 works in tandem with the growth hormone produced by your
pituitary gland. The IGF-1 hormone plays an important role,
particularly in childhood. It helps with the process of growing
bones, muscles, and tissues.
An IGF-1 test uses a sample of your blood to measure how much of
this hormone is circulating through your bloodstream. Having low
levels of IGF-1 might show some effects, as you'll see later in
this article.
In adulthood, IGF-1 continues to influence your health
significantly. For example, it plays an essential role in tissue
repairs, maintains healthy bones, and, more importantly, helps
develop lean muscle mass.
What Does IGF-1 Do In the Body
Let's take a closer look at the most critical functions of IGF-1
to understand how important it is for your health. For example,
IGF-1 is responsible for increasing muscle mass, provided that
the person in question also works out regularly.
IGF-1 also maintains lean muscle and prevents a process known as
atrophy. It also stimulates the growth of bones, and it provides
energy for the body to do tissue repair processes such as for
healing wounds and so on.
On top of that, IGF-1 also plays a crucial role in lipid
metabolism. This means the process of burning fats stored
throughout your body. In some cases, overweight and obese people
might also struggle with IGF-1 deficiency as this hormone is
vital for fat metabolism.
IGF-1 also helps with glucose metabolism. Glucose is also known
as blood sugar and it's the main source of fuel for your body.
Glucose is pushed by insulin into cells to produce energy. IGF-1
helps with this process, so the sugar in your blood is used
effectively.
Symptoms of Having Low IGF-1 Levels
Having too much IGF-1 is rare, and it might happen during the
early stages of life. In such cases, children grow very tall,
and this condition is known as gigantism. Low IGF-1 issues are
more prevalent, and they can affect both children and adults.
For example, here are the main symptoms of having too little
IGF-1 in your system.
Anxiety and depression
Excessive fatigue
Low exercise performance
Loss of muscle mass
Thin skin that gets wounded easily
Reduced bone density
Some of these effects might be subtle, and you might not even
know that they are caused by too little IGF-1 in your body.
Also, many of these symptoms are shared by other health
conditions, so it can be tricky to identify which ailment is the
culprit.
That's why it's essential to do an IGF-1 test if you feel
lethargic most of the time. Excessive tiredness might be caused
by various factors such as low testosterone, low blood iron
levels, but also because you might have too little IGF-1.
Causes of Low IGF-1
There are a few reasons why people might experience low levels
of IGF-1 in the body. Remember that the pituitary gland produces
a growth hormone that works in tandem with IGF-1. IGF-1 itself
is mainly produced in the liver but also in other parts of the
body.
One reason you might have low levels of IGF-1 is an underactive
pituitary gland. This might be accompanied by low levels of
thyroid hormones since the thyroid is also stimulated by the
pituitary. In rare cases, pituitary tumors might prevent the
proper release of growth hormone too.
Since IGF-1 works together with growth hormone, an insensitivity
to GH might also cause symptoms such as the ones mentioned
above. This problem can be genetic or inherited. For example,
those with kidney or liver disease might develop an
insensitivity to GH, which would result in low IGF-1 levels.
IGF-1 in Relation to Testosterone and ED
A couple of studies done in the last decade look at the link
between IGF-1 and testosterone. It has been discovered that
administering higher doses of testosterone exogenously might
increase IGF-1 levels also. This means the administration of
testosterone using creams, injections, or other methods.
Men on testosterone replacement therapy might benefit from this
type of treatment by seeing their IGF-1 levels go up. The study
data suggest that this increase is visible after at least six
weeks of TRT.
At the same time, having higher IGF-1 levels might also
alleviate erectile dysfunction in some men. ED is a prevalent
problem for those with low testosterone levels and/or seniors. A
study found that increasing IGF-1 levels (as well as GH levels)
could improve sexual function in men.
Having more IGF-1 is likely more beneficial for adults than
having less of it. That's why you might be interested in natural
ways you can increase IGF-1. This is entirely possible, and one
of the simplest ways to do it is to lose body fat.
Excessive fat automatically lowers IGF-1 levels, so you might
want to increase your weekly exercising time to lose weight.
Fasting can also be used to increase IGF-1 levels. There are
many types of fasting, and intermittent fasting is one of the
most popular types.
Order The IGF-1 Lab Test Today!
As you can see, the increasing interest in IGF-1 is justified as
this hormone is so important when it comes to your health. If
you experience some of the symptoms mentioned above or you want
to see how you stand, make sure that you order an IGF-1 blood
test as soon as possible.
To get excellent value for money and receive the results in just
a few business days, go to DiscountedLabs.com and order the
affordable IGF-1 lab test today!
IGF-1 Reference Range(s)
Pediatric
<1 Years
1-1.9 Years
2-2.9 Years
3-3.9 Years
4-4.9 Years
5-5.9 Years
6-6.9 Years
7-7.9 Years
8-8.9 Years
9-9.9 Years
10-10.9 Years
11-11.9 Years
12-12.9 Years
13-13.9 Years
14-14.9 Years
15-15.9 Years
16-16.9 Years
17-17.9 Years
Adult
18-19.9 Years
20-24.9 Years
25-29.9 Years
30-39.9 Years
40-49.9 Years
50-59.9 Years
60-69.9 Years
70-79.9 Years
>80 Years
Z-Score (Male)
Z-Score (Female)
References:
1. Pastuszak AW, Liu JS, Vij A, Mohamed O, Sathyamoorthy K,
Lipshultz LI, Khera M. IGF-1 levels are significantly correlated
with patient-reported measures of sexual function. Int J Impot
Res. 2011 Sep-Oct;23(5):220-6
2. Smith, Roy G. Human Growth Hormone Research and Clinical
Practice.
3. Hobbs CJ, Plymate SR, Rosen CJ, Adler RA. Testosterone
administration increases insulin-like growth factor-I levels in
normal men. J Clin Endocrinol Metab. 1993 Sep;77(3):776-9.
4. Agnieszka Swiecicka, Mark Lunt, Tomas Ahern, Terence W.
O'Neil. Higher Anabolic Hormone Levels Predict Lower Risk of
Worsening Frailty in Men: Prospective Results from the European
Male Ageing Study. Presented at Endocrine Society Annual Meeting
2017
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