Abstract
The use of anabolic steroids to increase physical performance and for aesthetic ends has reached alarming indices in the last three decades. Besides the desired actions, several collateral effects have been described in the literature, such as the development of some types of cancer, ginecomasty, peliosis hepatis, renal insufficiency, virilization, amongst others.
The most proeminent effect on human thyroid function is the reduction of thyroxine binding globulin (TBG), with consequent reductions of total serum T3 and T4, depending however on the susceptibility of the drug to aromatization and subsequent transformation into estrogen. In rats, anabolic steroids also act in the peripheral metabolism of thyroid hormones and seem to exert an important proliferative effect on thyroid cells. Thus, the aim of the present paper is to review data on the effect of supraphysiological doses of anabolic steroids on thyroid function, showing the danger that indiscriminate use of these drugs can cause to health.
[Abuse of anabolic steroids and its impact on thyroid function]. - PubMed - NCBI
Full text in Portuguese but reading it with an online translation
Abuse of anabolic steroids and its impact on thyroid function
Chronic administration of anabolic androgenic steroid alters murine thyroid function.
Fortunato RS1,
Marassi MP,
Chaves EA,
Nascimento JH,
Rosenthal D,
Carvalho DP.
Author information
Abstract
PURPOSE:
The administration of anabolic-androgenic steroids (AAS) to improve athletic performance has increased notably during the past three decades, even among nonathletes. Thyroid function is affected by AAS use in humans, although the mechanisms of the effects of AAS are unclear. We evaluated the effects on thyroid function of supraphysiologic doses of nandrolone decanoate (DECA), which is one of the most anabolic-androgenic steroids (AAS) used.
METHODS:
Male Wistar rats were treated with vehicle or 1 mg.100 g(-1) body weight (b.w.) of DECA, once a week for 8 wk, intramuscularly. We analyzed thyroperoxidase (TPO) activity, type 1 iodothyronine deiodinase (D1) activities in liver, kidney, pituitary, and thyroid, and serum levels of total T3, total T4, free T4, and TSH. Parametric and nonparametric t-tests were employed for statistical analyses.
RESULTS:
Treated animals showed a significant increase in the weight of kidneys and heart, and a decrease in the relative testis weight. Retroperitoneal adipose tissue was only slightly decreased.
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. Thyroperoxidase activity was unaltered, whereas liver and kidney D1 activities were significantly increased, but pituitary and thyroid D1 did not change.
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
Even Patrick Arnold seems to agree:
Bodybuilders who use large amounts of anabolic steroids often report lethargy as a side effect. Sleepiness, irritability, and foggy-headness are commonly reported by users of some of the more powerful anabolic steroids in large dosages. The cause of this lethargy has been the subject of debate in the performance-enhancement drug community, and the solution may be multifactorial. Published studies have given reason to suspect that thyroid hormone suppression may be one of these factors.
THYROID HORMONES
There are two major thyroid hormones, T4 and T3. T3 is considered the most active thyroid hormone, and its job is to act as a sort of ter regulator of every major aspect of metabolism- from protein thesis to carbohydrate and fat oxidation. T3 acts in general as a metabolic stimulator, and in addition to its influence on how the uses fuel for energy and tissue building, it also works to generate heat production (thermogenesis) via enhancement of uncoupling protein 1 (UCP-1) expression in the liver.
The production of too much thyroid hormone (hyperthyroidism) and too little thyroid hormone (hypothyroidism) are both undesirable conditions. Hyperthyroidism leads to overstimulation of the nervous system (resulting in elevated heart rate and nervousness), as well loss of lean body mass due to protein catabolism. Hypothyroidism; the other hand, leads to depression and fatigue, as well as other symptoms such as joint pain, sensitivity to cold, and fat gain.
ANABOLIC STEROIDS AND THYROID SUPPRESSION
As I stated in my introduction, published studies have confirmed that anabolic steroid use can suppress thyroid hormone levels in the blood. It appears that this is not due so much to a decrease in the production of the main thyroid hormone (T4) in the thyroid gland, however. What really is the culprit of the suppression is debatable, as different studies have found different things. Two things are clear, though. The levels of total and free active thyroid hormone (T3) are decreased with anabolic steroid use, and T4 thyroid hormone-binding globulin levels are markedly elevated. However, free T4 appears to be unchanged, as does TSH, which is the hormone that your brain produces to stimulate thyroid hormone production in the thyroid gland. So what is happening is not entirely clear. It may be a combination of disrupted conversion of T4 to T3 and/or interference of bioavailable T4 levels by excessive T4 thyroid hormone-binding globulin. Whatever the case, levels of the active thyroid hormoneT3 can be suppressed by anabolic steroid use- particularly at higher dosages. Such suppression can interfere with maximum muscle growth from a cycle, as optimal protein synthesis activity is dependent upon ideal T3 levels in the body.
It is interesting to note that bodybuilders have discovered by trial and error that thyroid hormone supplementation leads to greater gains during a cycle. I am pretty sure that this anecdotal discovery was made without the knowledge that AAS (anabolic-androgenic steroid) usage is thyroid suppressive.
