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Testosterone riskier for fat men with short androgen receptor genes

Some bodybuilders can use stuff literally for years without stopping, going through as much trenbolone, nandrolone, and testosterone in a week as a modest juicer does in a complete course. To make matters worse they experience no pain, while others are told by their doctors to stop after just six tiny doses of Sustanon. So how does that work? Endocrinologists from Muenster in Germany came up with some indicators. Fat percentage and the length of the gene for the androgen receptor determine how risky testosterone is for men.

Testosterone undecanoate

Testosterone riskier for fat men with short androgen receptor genes

The researchers describe an experiment they did with 66 men in the Journal of Clinical Endocrinology & Metabolism. The men did not produce enough testosterone themselves, so the researchers gave them injections of Nebido, a new testosterone preparation produced by Bayer Schering Pharma. Bayer Schering Pharma is the new name for what used to be Schering, and Nebido is an injectible testosterone undecanoate (TU). TU is a long-acting ester based on castor oil. The men got a 1000 mg injection mg in weeks 0, 6, 18 and 30. This schedule allows the testosterone level to rise gradually, reaching the desired level by week 30. After week 44, the researchers gave the men an injection if their testosterone level dropped below the week-30 level.

During the testosterone course which by the way was pretty modest the researchers monitored the men for side-effects. They measured cholesterol levels, thickness and haemoglobin levels in the blood, as well as heart rate and blood pressure in the men. Now 16 of the men in the study had a BMI of higher than 30. That counts as obese. [In this case you can exclude the possibility of the extra kilograms being the result of hard but healthy muscle mass.] The researchers discovered that it was the fat men who reacted badly to the Nebido course.

In the figure below you can see the chance of the fat men exceeding a critical value compared to that of the not-so-fat men.

Testosterone riskier for fat men with short androgen receptor genes

The less fat you have, the less likely you are to develop side effects from steroids.

Another factor is genetic tendency. To be more precise: the length of your gene for coding the androgen receptor in your cells. This is the protein that testosterone or other androgen steroid hormones have to attach themselves to in order have an effect. The gene for the receptor contains a piece of genetic material that repeats itself: the CAG sequence. The number of times that the gene repeats the sequence varies from 15 to 35. The fewer the number of CAG sequences, the greater the chance that testosterone will make men's blood too thick.

The figure below shows the relationship between the concentration of testosterone reached in the blood, the number of CAG sequences, for the androgen receptor and the thickness of the blood. If the blood becomes so thick that the haematocrit value rises above 50 percent, doctors halt testosterone therapy.

Testosterone riskier for fat men with short androgen receptor genes

Still. You can't do anything to change your androgen receptor, but you can do something about your fat percentage. If you want to use steroids as safely as possible, it's worthwhile thinking about reducing your fat percentage first. The same researchers recently published a study in which they provide another reason to start on steroids only once your fat percentage is low enough: they discovered that low-fat bodies are thriftier with their testosterone.

J Clin Endocrinol Metab. 2007 Oct;92(10):3844-53.

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