Unfortunately, not everyone who works with them discusses, advises on, or is responsible for testosterone. Yes, there are many doctors who discuss testosterone but know nothing about it. For example, it has a half-life of about 7 days. That means that in about 7 days, half of the medication will be out of your system or will no longer be acting on you. So, if you're at 1000 on Monday, which is shot day, you'll most likely be around 500 the following Monday if the math holds. This is critical when taking blood to check your testosterone levels. All too often, people will get their shot on Monday and then have their blood drawn on Tuesday or Wednesday.