From Elmer Cranton, M.D.
Re: IGF-1 interpretation
The following must be considered when relying on IGF-1 reports:
1. I have found that laboratories are not always accurate in
testing IGF-1 (sometimes called somatomedin-C). Different methods are used by different labs and the results are not always
comparable. It is a mistake to believe that clinical laboratory
reports are always reliable. IGF-1 is a very specialized test. Unless a lab is large enough to have a substantial volume for that special test, calibration and standardization may not be
accurate. I have found that Smith Kline Lab, LabCorp Lab, and
King James OmegaTech Lab are the most reliable. That doesn't mean
that others may not also be good. But be suspicious of reports if
they don't make sense clinically.
2. IGF-1 is not HGH It is a metabolic breakdown product made
from HGH by the liver. IGF-1 has some hormone activity by itself
but HGH in its pure form has much broader activity. Because HGH
remains in the blood for only a few minutes before attaching to
cell receptors, IGF-1 is used as an easily obtained but partial
indicator. IGF-1 stays in the blood for a day or more. IGF-1
seems to be reliable as a guideline for internal pituitary
production, which is pulsitile over many hours. But people differ
widely in the amount of IGF-1 produced from HGH by injection. I
have seen patients with only mild increases in IGF-1 from
injected HGH respond quite dramatically, out of proportion to
3. The fact is that 1 unit of HGH equals the total daily
pituitary production for a healthy young adult. Therefore one unit of HGH daily is a total replacement dose in old age, regardless of the IGF-1 followup. It is possible that more of the HGH taken by injection (once or at most twice daily) attaches to cells receptors in the body, perhaps more effective ones, and that less goes to the liver to be broken down to IGF-1.
4. I do not do routine follow-up IGF-1 blood tests in my patients for the above reasons. Those measurements have not correlated with replacement doses and vary widely from person to person. There is a wide variation in how much IGF-1 increases from person to person. This seems to have no significance to long-term benefit seen in my clinical practice.
THE DEGREE OF INCREASE IN IGF-1 DOES NOT SEEM TO CORRELATE WITH CLINICAL
BENEFIT. BUT THE LEVEL OF BASELINE IGF-1, BEFORE INJECTIONS BEGIN, AS A PRODUCT
OF SLOW AND CONTINUOUS PITUITARY RELEASE, DOES SEEM TO BE A RELIABLE INDICATOR OF HOW DEFICIENT A PERSON IS TO BEGIN WITH.
5. I know that for myself personally, each unit of HGH by injection raises my IGF-1 by 100 nanograms/milliliter (ng/ml). That is my own consistent measurement if the HGH is real and not counterfeit. Someone else may have a different reading, more or less, with no significance to benefit. I am 67 years old and my baseline IGF-1 without replacement is approximately 100. Every time I get a new lot number of HGH for my patients I take one unit daily for one week and test my IGF-1. It should be about 200. I then take 2 units daily for several days and test again. It should be about 300.
That is the only way I can be sure of getting the real thing. Over the past 2 years I have twice received counterfeit HGH, properly labeled and otherwise indistinguishable from the real thing. When I tested my IGF-1, it remained at baseline.
I now use Lilly Humatrope in my practice. It has a foreign label but is made in France in the same factory as the USA product. It has consistently been the best in my own testing. IGF-1 measurements will also vary by 10% to 20% from day to day normally. And if a single blood specimen is split into two test tubes and sent to the same laboratory, the results may differ by 20%. The test method is only that accurate. Variations between different labs may be even greater. That fact must be considered in interpretation.
6. HGH replacement therapy means replacement therapy for deficiency with aging. Young people produce plenty of their own and young adults also respond much more briskly to precursors (various amino acids). When reading claims for precursors of any type, it is necessary to know if IGF-1 was deficient to begin with. I would ask to see results for a series of 10 patients over 70 years old (whose IGF-1 will be around 100, plus or minus) and then get before and after readings. They must be 10 sequential patients, not the best 10 responders out of 100, as may be deceptively done. On the average I have only seen about 25% increase of IGF-1 with amino acids in such patients. And to get that increase it is necessary to have an empty stomach, no food for several hours before and 2 hours after taking that product. Food competes with the amino acids for absorption. It is necessary for amino acids to go in fast without interference from other foods to boost HGH release. Young people who do not need HGH and who will not benefit from more will increase much more with the amino acids than old people who really need it.
7. It is well known that HGH releasers (peptides, amino acids, releasing hormone, etc.) lose there effect over time. The pituitary becomes tolerant to them and releases less and less HGH over several months. They work best short term, best in young
people who don't need the benefit and lose their effect with
Elmer M. Cranton, M.D.
> From: "Dale R. & Karen A. Hersh"
> Dear Dr. Cranton,
> Thank you so much for you information, but I do have one
question reference point 5: Do you regularly use rHGH and if you don't why? -- And if you do -- do you cycle it?
I regularly take one to two units of rHGH daily, every day. I've done that for 3 years now with good results. I do not cycle it.
Cycling can save money and get more bang for the buck, but has
reduced overall benefit.
E M Cranton, MD
From: "Elmer Cranton, M.D."
Subject: IGF-1 Laboratory Tests
I did a comparison study of IGF-1 test results by sending split specimens to several large, very reputable reference laboratories.
I took a single blood specimen, I split it into two tubes and sent them to two different laboratories. Theoretically the results should have been the same. There was a correlation but also large differences.
The results follow:
The two test results are on the same, identical blood specimens.
The laboratories are large, highly reputable, fully licensed
labs, approved, and regularly inspected by the government. This
cost me some money as each test cost more than $60. But I felt it
was necessary to correctly interpret my patients' results.
When you see IGF-1 figures used in marketing, you should keep the below results in mind. Any such figures mean nothing unless the standard deviation of the method used is known and enough tests are done to get a statistically significant difference. A you can see, differences of 25% to 50% are within the error of the method and can be quite meaningless.
It is also easy for a marketer to select the most favorable numbers and discard those that do not favor a product. How can one be sure this is not done? Unless the research is done independently, by a researcher with nothing to gain or lose form the results, such studies are always suspect in my mind. If a marketing company pays for research, will the researcher bite the hand that feeds him/her???
IGF-1 on same specimen, ng/ml
I am now repeating this test by sending samples of the same blood
to the same lab on different weeks to see the differences in
results using the same lab both times.
So far the results are similar to the above, although the
differences are less.
Elmer M. Cranton, M.D.
Correlation of IGF-1 and Prostate Cancer
A good study has shown that a large number of elderly male patients
taking HGH over a long time had no increase in prostate cancer.
That rumor got started when it was reported that elderly men with
the lowest quintile of IGF- (lowest fifth of HGH) had less cancer
than men with the highest 20% (highest fifth). There was no
linear correlation of IGF-1 and prostate cancer in the study.
They only reported less cancer in the most deficient of an
What that report did not point out was that the lowest fifth were
so deficient that all tissues of the body were inhibited in
growth, healing and maintenance-- healthy as well as cancerous. It
is quite a different thing to state that deficiency of essential
hormones slows the growth of cancer (and everything else
including a healthy body) and, on the other hand, trying to prove
that hormones cause cancer. Life and health cannot progress
without hormones. Cancer cannot progress without a living body to
support its growth. It is quite predictable that if old people
are dying from end stage deficiencies, they might have less
If all of the facts were reported, it is my opinion that the most
senile and debilitated of the group would also have been those in
the lowest 20% of IGF-1. But that data was not presented.
If HGH is only replaced to an average level present in the body
for 30 years, from age 20 to age 50, and if it was safe during
that 30 year period, and if it was essential to health during
those 30 years, what is the harm in replacing it after age 50
when it becomes deficient? If it's dangerous, why does it not
cause problems in the earlier 30 years when it is normally
present in the same levels or higher from pituitary production?
(Note: Excessively high doses of hormones can be harmful, I am referring here only to normal replacement doses).
E M CRANTON, MD
For more information on Dr. Elmer Cranton's EDTA Chelation Therapy or growth hormone replacement therapy, go to: www.drcranton.com.
Dr. Cranton's Replies Answers Questions referring to Growth Hormone (rHGH) Replacement Therapy!
Dr. Cranton Re: Growth Hormone Replacement
This and other posts by Dr. Cranton to the Rejuvenation board are found in Digest No. 26, 27, and 28, which are found in the Archives of the
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