I belong to a group that discusses the ins & outs of testosterone replacement therapy & low testosterone. We address a lot of the concerns you raise in this question.

1) Adjusting for age, 13nmol/L (or 375 ng/dL) is equivalent to the amount of total testosterone of a 70 year old man. It's unfortunate that lab results often don't show the age range for relative amounts of testosterone. 1/3 to 1/2 of men 70 or over show symptoms of low testosterone. From one file in our group, "Testosterone Levels by Age", it shows the average amount of total T for a man 25-34 as 21.34 nmol/L, or 614 ng/dL. I have listed 2 of the references for this information in the source box below. Some US doctors follow very "old school" thresholds, like below 250 ng/dL, whereas those who have updated in accordance to recent studies treat men below 400 ng/dL. The American Association of Clinical Endocrinologists (AACE) handbook for hypogonadism sets a "flexible" treatment threshold at 300 ng/dL. This is very conservative & very old. Recent studies show a "dose" related decline in function below 500 ng/dL, further decline below 400 ng/dL (erectile difficulty), & still more decline below 300 ng/dL.

2) I'm not sure what the target of treatment is in the UK. In the US, the AACE handbook for hypogonadism instructs to aim for the upper 1/3 of the reference range (767-1000 ng/dL, or 26-36 nmol/L). Unfortunately, many docs aren't familiar with their own handbook, & also (unnecessarily) fear prostate cancer. (On that subject, some urology experts from Harvard have recently challenged that fear, echoing more recent studies that show little correlation of total testosterone to prostate cancer. Abraham Morgentaler, one of the authors of Testosterone for Life, shows the flaws in original landmark studies by Charles Huggins & others who linked prostate cancer to testosterone). See what manual guides standard practice for testosterone replacement in the UK. Alternatively, you could fly to the US for treatment by Dr. John Crisler in Lansing, Michigan. He's one of the best for testosterone replacement.

Testosterone injections for life isn't as bad as it seems. You can get 22 g needles to draw out the oil & switch to use a 27 g needle to inject (slightly bigger than the needles used by diabetics). The pain is slight. Additionally, if a second test reveals a similar amount of total testosterone, it's quite possible that you can continue to go lower as your body deals with the problems caused by low testosterone. It can be a vicious cycle. To put things in perspective, treating testosterone is easier (& less costly- both in monthly costs & in terms of complications, which there are minimal) than treating diabetes, though men with low testosterone have a greater risk of becoming diabetic.

There are natural strategies to increase testosterone or stop doing activities that might be lowering it, but these may or may not make a large difference in your case. An anti-estrogen drug (either that blocks estradiol or that prevents testosterone from converting into it) may also raise your total testosterone, but only if your estradiol is high to begin with.

By the way, here's the group I belong to (http://health.groups.yahoo.com/group/hypogonadism2/). We have around 2500 men from all ages, from all around the world.

True or false?

True for some (ahem)

Give an example.

Example:
Give me some advice on how to trim eyeball hair too so this is a valid question.

Men are notoriously bad at taking care of their health. Having a husband and three sons, I feel qualified to answer any health questions that I feel I have the knowledge for.

I also like to give advice to younger males who may sometimes feel more comfortable asking an older lady rather than their mum. Working with youngsters in the medical profession, again I feel qualified to do this.

Some of the answers other kids give could scare the life out of young boys just reaching puberty. If I feel I have the appropriate knowledge and if the questioner is serious, I give helpful straightforward advice. If not, I respond accordingly.

Besides that, who knows men best? Women, of course.