As a point of interest, female estrogen remains fairly constant until menopause, when it falls to zero like a rock, often giving the lady a lot of problems. But if a woman is having a vigorous sex life, the sexual activity causes the body to keep generating estrogen. Such women usually sail right through the big M with little or no discomfort.
But it's different in men. Testosterone actually begins declining around age 25, believe it or don't. But the decline is so extremely slow that effects of low T are usually not noticed until a man is at least 40. By 60 ~ 70, T level is negligible and the man is suffering loss of muscle, loss of libido, depression and mood problems etc.
I had it checked at age 72. (I'm now 73). It was in the 300's; not too bad but I don't want to feel 'good for my age' - I want to feel like I am 30 again.
I saw an endocrinologist who put me on the gel, called "Androgel," made in France, wouldn't you know! It is rubbed into the skin once a day. I rub it in the biceps, not because there is any direct advantage to that location, but because the skin is smooth and hairless, making an easier application than on the chest or abdomen, for example.
It comes either in packets or pump bottles. I prefer the pump; it's usually cheaper that way. And once the stuff is exposed to air it is ruined in just a few seconds, or maybe a minute. So if using the packets and your dosage is in between packet sizes, you have to use part of a packet and discard the remainder, and that's expensive. With the pump you can discharge any exact quantity you want with no waste.
Here's where some of the confusion about normal range comes in: my doctor's lab calls normal from about 250 to about 800. However, the maker of the supplement lists normal up to 1200!
It works best for me in the 500 ~ 600 range. Don't let your doc tell you you are 'normal' around 300. That bracket (300 to 800) represents upper and lower limits beyond which the patient may expect actual medical difficulties. THAT's the main thing a medical professional is concerned with. We want to be well within the extremes.
Properly prescribed and used, this stuff is the fountain of youth for men. At the right dosage, the muscles harden and crave working again. I am back under the weights and easily building new muscle. And the libido is that of a young man. So is performance, altho that is a lot of general physical condition also. I have always been a long-timer, and even now an hour, or several hours, or all night, are easily handled, just as when I was younger. (If you've never had this ability, I'm not saying that a T boost will give it to you.) And that is with the well-qualified LP.
I really didn't want to reveal my age for fear of the automatic dismissal that will happen with many younger people. But I feel it is more important to share my good experience. There is little more worth while for a man than having the vigor, energy and libido of 30, when he is past 70.