I have been wondering about aromatase inhibitors and SHBG suppression for a while, and did some checking of the literature.
It appears that a link between aromatase inhibitors and decreased SHBG is somewhat inconclusive. I found four "relatively" (nothing found newer than '02) recent articles on the subject (see below).
The first (see below) found no siginificant changes in SHBG levels after four weeks of arimidex treatment in older men (~71 years) with prostate cancer. The second found a small but significant (16% 43.4+/- 4.8 vs 36.8 +/- 4.6nm/L) decrease in SHBG after up to 9 weeks of treatment in older men (~74yrs). However, the variation they show and overlap of SE makes their data seem suspect. One would also have to wonder if that small of a decrease is biologically relevant. The third study looked at aromatase treatment in teenage boys, and younger men, which may be more relevant to our concerns. They found no significant changes in SHBG after 10 days of arimidex (1mg/d) treatment.
Now, I don't want to pretend to be an expert on this, nor have I done an exhaustive review of the literature (maybe I missed an article which shows it conclusively). If it does have an effect on SHBG levels, could it be associated with sex (i.e. basal test levels), AAS use, or possibly it varies with the aromatase inhibitor used?
1: Smith MR, Kaufman D, George D, Oh WK, Kazanis M, Manola J, Kantoff PW. Selective aromatase inhibition for patients with androgen-independent prostate carcinoma. Cancer. 2002 Nov 1; 95(9): 1864-8.
PMID: 12404279 [PubMed - indexed for MEDLINE]
2: Taxel P, Kennedy DG, Fall PM, Willard AK, Clive JM, Raisz LG.
The effect of aromatase inhibition on sex steroids, gonadotropins, and markers of bone turnover in older men. J Clin Endocrinol Metab. 2001 Jun; 86(6): 2869-74.
PMID: 11397902 [PubMed - indexed for MEDLINE]
3: Mauras N, O'Brien KO, Klein KO, Hayes V.
Estrogen suppression in males: metabolic effects. J Clin Endocrinol Metab. 2000 Jul; 85(7): 2370-7.
PMID: 10902781 [PubMed - indexed for MEDLINE]