Nandrolone and anabolic steroids effect on thyroid

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I know nothing about the subject, but got curious and found this article on Google Scholar, a copy/paste from some journal. It's conclusion:

In conclusion then AAS seem to have little if any effect on thyroid function per se. The reports by Deyssig & Weissel, and Daly et al suggest the possibility of a direct action of AAS on the thyroid or pituitary, but their results are inconsistent: The former researchers detected elevated stimulated TSH while the latter saw an increase in basal TSH. Free T4 was unchanged in former group, while it was elevated in the latter. The only consistently reported effect is a depression in total T4, total T3 and TBG. If there is a direct effect of AAS on the thyroid, pituitary, or hypothalamus the studies conducted so far shed little light on the mechanism due to their inconsistent results. And as stressed by Deyssig & Weissel any direct effect of anabolic steroids on the thyroid would likely be of no clinical significance due to its small magnitude.

From a practical standpoint for those concerned that anabolic steroids might suppress the thyroid it is a simple matter to incorporate low dose (25 to 50 mcg/day) T3 into a cycle to enhance fat loss while at the same time only minimally if it all compromising gains in muscle mass (10). In (10) one group of subjects was given T3 alone while the other was given a combination of T3 and testosterone enanthate, 200 mg/week. After 28 days of bed rest, the men in the T3 group lost an average of 3.9 kg of body weight (i.e. from 82.0 ± 7.1 to 78.1 ± 7.1 kg). Body weight in the T3 plus testosterone-treated subjects declined by only 1.0 kg (78.9 ± 4.9 to 77.9 ± 4.9 kg). Lean body mass declined by 1.5 kg in the T3 group, whereas the T3 plus testosterone-treated subjects experienced nearly a 2-kg increase in lean mass (i.e. 1.7 ± 0.9 kg). Of course we don’t know how much mass the test plus T3 group would have gained had they foregone the T3. Nevertheless these are still impressive gains considering the subjects were forced to lie in bed for 28 days with no exercise, and considering that no special dietary measures were imposed to preserve or increase muscle mass.

(10) Zachwieja JJ, Smith SR, Lovejoy JC, Rood JC, Windhauser MM, Bray GA. Testosterone administration preserves protein balance but not muscle strength during 28 days of bed rest. J Clin Endocrinol Metab. 1999 Jan;84(1):207-12.


Thank you for your response!

I started this topic when I saw this study on Nandrolone’s decreasing effect on free T3 and T4. Please see link below.

DECA treatment induced a significant increase in the absolute and relative thyroid gland weight. The concentrations of total serum T3, free T4, and TSH decreased significantly with treatment, but total serum T4 levels were unchanged.“

CONCLUSION: Our data indicate that DECA exerts direct actions on the thyroid gland and in the peripheral metabolism of thyroid hormones and might lead to thyroid dysfunction.”

Chronic administration of anabolic androgenic steroid alters murine thyroid function. - PubMed - NCBI

Nelson Vergel

Anabolics and higher dose T can decrease not only sex hormone binding globulin but also thyroxine binding globulin. T3 uptake increases. I am not sure why long term anabolic users tend to have higher TSH (above 3.5) even in the absence of lower free T3 and free T4. Sublinical hypothyroidism?

anabolics thyroid SHBG.jpg

Androgenic-anabolic steroid effects on serum thyroid, pituitary and steroid hormones in athletes


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Nelson Vergel

High dose (500 mg/week) testosterone therapy in female-to-male transgenders.

Eur J Endocrinol. 2006 Jul;155(1):11-6.

The effects of sex-steroid administration on the pituitary-thyroid axis in transsexuals.
Bisschop PH1, Toorians AW, Endert E, Wiersinga WM, Gooren LJ, Fliers E.

Estrogen and androgen administration modulate the pituitary-thyroid axis through alterations in thyroid hormone-binding globulin (TBG) metabolism, but the effects of sex steroids on extrathyroidal thyroxine (T4) to triiodothyronine (T3) conversion in humans are unknown.

We studied 36 male-to-female and 14 female-to-male euthyroid transsexuals at baseline and after 4 months of hormonal treatment. Male-to-female transsexuals were treated with cyproterone acetate (CA) 100 mg/day alone (n = 10) or in combination with either oral ethinyl estradiol (or-EE) 100 microg/day (n = 14) or transdermal 17beta-estradiol (td-E) 100 microg twice a week (n = 12). Female-to-male transsexuals were treated with i.m. testosterone 250 mg twice a week. A t-test was used to test for differences within groups and ANOVA with post hoc analysis to test for differences between the groups.

Or-EE increased TBG (100 +/- 12%, P < .001) and testosterone decreased TBG (-14 +/- 4%, P = 0.01), but free T4 did not change. Td-E and CA did not affect TBG concentrations. TSH was not different between groups at baseline or after treatment. CA decreased T3/T4 ratios (-9 +/- 3%, P = 0.04), suggesting that T4 to T3 conversion was lower. Testosterone increased T3/T4 ratios (30 +/- 9%, P = 0.02), which probably reflects higher T4 to T3 conversion.

Oral but not transdermal estradiol increases TBG, whereas testosterone lowers TBG. Testosterone increases T3/T4 ratios. Estradiol does not affect T3/T4 ratios, irrespective of the route of administration.
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