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GH use vs. Aromatase Inhibitors


Jun 5, 2002
I need to find the studies again, but if memory serves, it has been shown in the scientific literature that aromatase inhibitors (like arimidex) reduce IGF-1 levels, which is probably why some people say "hey, don't use anti-e's unless you need to, it hurts gains"...

Now as we all know GH works by being metabolized in the liver into IGF-1 which spurs tissue growth. (Note that its also been shown that some steroids increase IGF-1) So what does this all mean?..... bear with me here, if you are using Aromatizing Gear (e.g. Testosterone) and an aromatase inhibitor (e.g. Arimidex) and adding in GH, are you possibly lessening your gains because the Anti-e is in part reducing IGF-1 levels?

And if this is the case, could one argue that the best time to use GH is with gear that doesn't aromatize? For example, Tren + Winny + Anadrol + GH?

I'll see if I can dig up the research to support this, but I'm mostly interested in hearing real world experiences,


Effect of low dose tamoxifen on the insulin-like growth factor system in healthy women.

Bonanni B, Johansson H, Gandini S, Guerrieri-Gonzaga A, Torrisi R, Sandri MT, Cazzaniga M, Mora S, Robertson C, Lien EA, Decensi A.

Division of Chemoprevention, European Institute of Oncology, Milan, Italy.

The use of tamoxifen as a preventive agent may be limited by the increased risk of endometrial cancer and venous thromboembolic events observed in postmenopausal women. We have recently shown a comparable activity of lower doses of tamoxifen on several surrogate biomarkers of cardiovascular disease and breast cancer, including Insulin-like Growth Factor-I (IGF-I). To provide further insight into the effect of tamoxifen at low doses on the IGF system, we have correlated the drug serum levels attained after 2 months of either placebo (n = 32), tamoxifen 20 mg/day (n = 26), 10 mg/day (n = 23) or 10 mg/every other day (n = 29) with the changes in IGF-I, Insulin-like Growth Factor-II (IGF-II), Insulin-like Growth Factor Binding Protein-1 (IGFBP-1), Insulin-like Growth Factor Binding Protein-3 (IGFBP-3), and IGF-I/IGFBP-3 ratio. Compared with placebo, tamoxifen induced a mean +/- standard error (SE) reduction of IGF-I of 16.9 +/- 7.8%, p < 0.05, a non-significant increase of 22.9 +/- 12.2% in IGF-II, an increase in IGFBP-1 of 49.3 +/- 22.7%, p < 0.05, and a non-significant change of IGFBP-3 (-4.0% +/- 9.2). No significant concentration-response relationship was observed between serum tamoxifen concentrations and the biomarker changes except for the ratio of IGF-I/IGFBP-3, which decreased by 1.53 +/- 0.68% for any increase by 10 ng/ml of serum tamoxifen concentration (p = 0.02). Although low tamoxifen concentrations induce a comparable modulation of the IGF family relative to the conventional dose, the lower decrements in the IGF-I/IGFBP-3 ratio observed at low drug concentrations might be associated with a reduced preventive activity. Further studies on the search of the minimal active dose of tamoxifen are warranted.

Publication Types:
Clinical Trial
Randomized Controlled Trial

PMID: 11759825 [PubMed - indexed for MEDLINE]



Short-term effects of anastrozole treatment on insulin-like growth factor system in postmenopausal advanced breast cancer patients.

Ferrari L, Martinetti A, Zilembo N, Pozzi P, Buzzoni R, La Torre I, Gattinoni L, Catena L, Vitali M, Celio L, Seregni E, Bombardieri E, Bajetta E.

Nuclear Medicine, Istituto Nazionale per lo Studio e la Cura dei Tumori of Milan, Via G. Venezian, 1, 20133, Milan, Italy

Insulin-like growth factors (IGFs) play a fundamental role in cancer development by acting in both an endocrinal and paracrinal manner, and hormone breast cancer treatments affect the IGF system by modifying circulating growth factor levels. We evaluated total IGF-1, IGF-2, IGF binding protein (IGFBP)-1 and IGFBP-3 in the blood of 34 postmenopausal advanced breast cancer patients (median age 63 years, range 41-85) treated with anastrozole, a non-steroidal structure aromatase inhibitor (NSS-AI). The plasma samples were obtained at baseline, and after 2, 4, 8 and 12 weeks of treatment. The IGFs were quantitated by means of sensitive radioimmunoassays (RIAs). IGF-1 significantly increased during anastrozole treatment (baseline versus 12 weeks, P=0.031), IGF-2 showed a trend towards an increase, and IGFBP-1 constantly but not significantly decreased; IGFBP-3 did not seem to be affected at all. The anastrozole-induced changes in IGFs and IGFBP-1 appeared to be different in the patients receiving a clinical benefit from those observed in non-responders. We have previously shown that letrozole (a different type of NSS-AI) modifies blood IGF-1 levels, and the results of this study of the biological effects of anastrozole on the components of the IGF system confirm our previous observations.

PMID: 11983488 [PubMed - in process]
Bottom line-nolvadex does decrease igf1 levels and should not be used with gh.
Arimidex may actually increase igf1 levels, does not at all decrease them, and can be used with gh.

Just curios what is GH going for these days? 400-500 a kit or is that way off??
also, the notion of not using an anti-e while on cycle cuz it hurts gains is based on the mistaken notion that E is needed for anabolism, go over to animals site and read the post in the faq section titled"Just say no to E". the idea if nolvadex as bad is that it hinders igf production
The effects that Nolvadex has on IGF1 are so small, in real life they are not a concern as far as gains go.
People that think that they gain less on Nolvadex believe that because they retain less water, so they add less weight, so they think that they are not gaining as much muscle, which is erroneous.
What about Letrozole - that's what I'm using next cycle. I don't have a copy of Study but it's puported to "increase" IGF levels!!!

More Questions

wolverine said:
Effect of low dose tamoxifen on the insulin-like growth factor system in healthy women.
What's your thoughts on this study - since it's on "low dose" Nolva? The amounts taken as a male anti-e are probably substantial in comparison to amounts in Study (50mg for males vs. 20 & 10mg in Study)?!?!

using nolva with d-bol, will that curtail some of the bloat? are nolvas effects so minor it wont inhibit water bloat?
Wolverine and MikeS....

our studies and conclusions disagree..... here's the study that I based the finding that Arimidex lowers IGF-1 levels on:

Estrogen Suppression in Males: Metabolic Effects1
Nelly Mauras, Kimberly O. O’Brien, Karen Oerter Klein and Valerie Hayes
Nemours Research Programs at the Nemours Children’s Clinic (N.M., V..H.), Jacksonville, Florida 32207; DuPont Hospital for Children (K.O.K.), Wilmington, Delaware 19803; and The Johns Hopkins University School of Hygiene and Public Health (K.O.O.), Baltimore, Maryland 21205-2179


We have shown that testosterone (T) deficiency per se is associated with marked catabolic effects on protein, calcium metabolism, and body composition in men independent of changes in GH or insulin-like growth factor I production. It is not clear, however, whether estrogens have a major role in whole body anabolism in males. We investigated the metabolic effects of selective estrogen suppression in the male using a potent aromatase inhibitor, Arimidex (Anastrozole). First, a dose-response study of 12 males (mean age, 16.1 ± 0.3 yr) was conducted, and blood withdrawn at baseline and after 10 days of oral Arimidex given as two different doses (either 0.5 or 1 mg) in random order with a 14-day washout in between. A sensitive estradiol (E2) assay showed an approximately 50% decrease in E2 concentrations with either of the two doses; hence, a 1-mg dose was selected for other studies. Subsequently, eight males (aged 15–22 yr; four adults and four late pubertal) had isotopic infusions of [13C]leucine and 42Ca/44Ca, indirect calorimetry, dual energy x-ray absorptiometry, isokinetic dynamometry, and growth factors measurements performed before and after 10 weeks of daily doses of Arimidex. Contrary to the effects of T withdrawal, there were no significant changes in body composition (body mass index, fat mass, and fat-free mass) after estrogen suppression or in rates of protein synthesis or degradation; carbohydrate, lipid, or protein oxidation; muscle strength; calcium kinetics; or bone growth factors concentrations. However, E2 concentrations decreased 48% (P = 0.006), with no significant change in mean and peak GH concentrations, but with an 18% decrease in plasma insulin-like growth factor I concentrations. There was a 58% increase in serum T (P = 0.0001), sex hormone-binding globulin did not change, whereas LH and FSH concentrations increased (P < 0.02, both). Serum bone markers, osteocalcin and bone alkaline phosphatase concentrations, and rates of bone calcium deposition and resorption did not change. In conclusion, these data suggest that in the male 1) estrogens do not contribute significantly to the changes in body composition and protein synthesis observed with changing androgen levels; 2) estrogen is a main regulator of the gonadal-pituitary feedback for the gonadotropin axis; and 3) this level of aromatase inhibition does not negatively impact either kinetically measured rates of bone calcium turnover or indirect markers of bone calcium turnover, at least in the short term. Further studies will provide valuable information on whether timed aromatase inhibition can be useful in increasing the height potential of pubertal boys with profound growth retardation without the confounding negative effects of gonadal androgen suppression.

So - here IGF-1 levels decreased 18% due to Arimidex (and this is in 16 yo boys as opposed to 60 yo post-menapausal women - not that either is a great data point for our purposes)

My original question still remains.......:confused:

Last edited:

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