Upon hearing these words, some parents freak out. They think their children are considering suicide. They have concerns about their child's mental and emotional stability. They worry that their children are unhappy.
It's probably true that the child is unhappy. This unhappinesss in not a bad thing. It is likely temporary and in response to frustration, a frustration perhaps caused by their parents. And seeing to it that your children are occasionally frustrated is a good thing.
Typically, when kids say any of the following things--"I wish I was dead" or "I hate my life" or "I can't stand it here" or "You'll be sorry when I'm no longer around," it is typically code. It is not meant literally. Instead it should be translated as "I really don't like the way things are going right now" or "I'm very unhappy with the decision my parent just made."
These comments are usually made when the parent has said that the child cannot do something they wish to do (go to a party; have their own cell phone; wear unacceptable clothing) or they must do something they'd prefer not to (turn off the video game; get ready for bed; do homework). If this is the manner of their remarks, there is no worry about suicide.
While any comment regarding suicide must be evaluated for its seriousness, the context of the statement must be taken into consideration. Said in the fashion described above, there is no sense of serious suicidal intent.
If your child were to calmly make comments such as "Sometimes I wish I were dead" or "No one would miss me if I weren't around" then these statements should raise a parent's concern. They likely reflect, if not clear suicidal intent, some depression of mood which should be taken seriously and be addressed accordingly.
At that point the parent might wish to consider scheduling an appointment with their pediatrician or obtain a referral to a mental health professional who can assess the child's suicidal risk.
But if the child is merely temporarily unhappy with the limit-setting or value enforcement of his parents, then the comments should be seen as such and not cause alarm.