How does a doctor/local gp tell if you are "depressed"?

Diagnostic criteria: Diagnostic criteria are available for anyone. 2weeks of low mood, sadness, helpless, hopeless, worthless feelings, alteration in sleep, appetite, wt, negative thinking, fatigue, irritability , poor concentration, suicidal thinking, or wish to be dead, withdrawl are possible for any professional to look for and possibly identify. Some professionals , better at eliciting them, and gp's have less time.