5 replies to this topic

[albedo]

I have been looking at this Forum trying to find a reply to the following questions:

 

• Is there such a thing as an optimal or target blood circulating IGF-1 in humans, age-dependent and with respect to (i) health span, (ii) max. life span and (iii) increased/decreased risk of cancer?

 

I am not sure the questions are properly formulated but you might have been thinking along the same lines and found useful authors and literature.

 

Maybe a better formulation of the question?

 

Hopefully this subsection of the Forum is the appropriate place to post it.

 

[albedo]

An element of (at least a partial) reply can come from this study pointing to a U-shaped association curve.

 

" ...A recent study analyzed the available data to determine the relationship between circulating IGF-1 levels and mortality in the general population using random-effects meta-analysis and dose–response meta-regression (36). Analysis of 12 studies with 14,906 participants clearly demonstrates that in humans, there is a U-shaped association between circulating IGF-1 levels and all-cause mortality. Important for the present discussion, low levels of IGF-1 translate into a significantly increased mortality risk in the general population, predominantly due to an increased incidence of cardiovascular diseases. In contrast, higher IGF-1 levels are associated with an increased cancer mortality (36,37)..."

http://www.ncbi.nlm....C3348498/#bib36

 

Anyone has access to the refs. 36 and 37 cited in the study? Would appreciate!

 

In particular the Lancet study (37) points to an “…High concentrations of IGF-I were associated with an increased risk of prostate cancer...”. This is typically diagnosed later in life and is of particular concern to me.

http://www.ncbi.nlm....ubmed/15110491/

 

 

 

 

 

 

[albedo]

oops .. sorry ..ref 36 full text is here:

Meta-Analysis and Dose-Response Metaregression: Circulating Insulin-Like Growth Factor I (IGF-I) and Mortality

http://press.endocri...10/jc.2011-1377

[corb]

From a hormone testing website:

 

 

With all this talk of reference ranges, you may notice that few of the test descriptions on this web site  include the reference range. There are several reasons for this:

1. In general, reference ranges are specific to the laboratory that produces the test results. For many analytes, different laboratories use different kinds of equipment and different kinds of testing methods. This means that each laboratory must establish its own reference ranges using data from its own equipment and methods. The laboratory must supply your test result with an accompanying reference range on the laboratory report. Consequently, there is no such thing as a standard reference range. Of course, each test does have a theoretical reference range that we could include on this site, which can be found in many books and other online sources, but it may have little diagnostic meaning for you. You and your doctor should apply the reference range supplied by the laboratory performing the test.

   That being the case, however, for a few specific tests, such as the electrolytes, there is a high degree of consistency if not standardization, among clinical laboratories in the methodologies and procedures used for these particular tests. These laboratory methods have been in use for many years now so their reference ranges have been well-established and typically reflect numbers that are very similar to the theoretical reference range. Because of this greatly reduced variability in the reference ranges for these select number of tests, their reference ranges are included on this site. The source of the range for each test is Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, a well-respected and authoritative textbook on the subject that is used by medical professionals.

 

With that in mind here are two cohorts one asian and one american:

 

http://www.scielo.br...ipt=sci_arttext

 

 

http://synapse.korea...vmode=PUBREADER

 

 

[albedo]

Thank you Corb.

 

I agree with the text you quote at beginning of your post which I guess is from HERE. Indeed ref. ranges comparison is a common problem and also the reference 36 above clearly had to study percentiles of IGF-1 rather than absolute values:

 

“…Different immunoassays are used to measure IGF-I levels, each assay having specific reference ranges, which precludes a direct comparison of absolute IGF-I values (23). For this reason, the analyses were based on percentiles of IGF-I, assuming that different IGF-I assays reflect the same underlying distribution of IGF-I levels….”

http://press.endocri...10/jc.2011-1377

 

Herewith is what the Life Extension Foundation (LEF) reports as (age-dependent) reference range for IGF-1 (I think they work with LabCorp):

 

20 years              127–424 ng/mL                51–55 years        87–238 ng/mL

21–25 years        116–358 ng/mL                56–60 years        81–225 ng/mL

26–30 years        117–329 ng/mL                61–65 years        75–212 ng/mL

31–35 years        115–307 ng/mL                66–70 years        69–200 ng/mL

36–40 years        109–284 ng/mL                71–75 years        64–188 ng/mL

41–45 years        101–267 ng/mL                76–80 years        59–177 ng/mL

46–50 years        94–252 ng/mL                  81–85 years        55–166 ng/mL

http://www.lef.org/P...Testing/Page-04

 

I do not know what to do with some of the Anti-Aging community recommendation to keep "youthful” levels of hormones. Is this the right approach? It is not clear as I do not understand on which evidence you can base this strategy. The AA community gives “optimal” values in some cases, not for all hormones. LEF gives them for e.g. DHEA HERE but not for IGF-1 and I suspect because it is more dangerous to target the IGF-1 level you had in your 30's at say your 60’s or 70’s due to the U-curve and increased cancer risk. Others in the community do, e.g.:

 

Dr. Claude Dalle (President of the French Anti-Aging Medicine) gives in one of his books:

ref: 115-490 and optimal for men: 200-380 ng/ml

 

and Dr. Philip Miller in his “Life Extension Revolution” book:                                                                                

ref: 114-492 and optimal: 200-300 ng/ml

 

 

[IWS]

I'm interested in this too. I think it's a question of keeping a whole balance trying to compensate depending on the condition which makes you sick, I mean this is one of the substance you should think and use in an holistic way. There is an not so old (2007) spanish study where they reference the IGF-I for the liver cirrhosis treatment also mentioning concerns about neoplastic cancer risk etc. it's a worth reading:

http://scielo.isciii...082007000300007