Can anyone tell me how to detect protein deficiency?

To be protein deficient in a developed country is very rare nowdays, but if you are you would have symptoms such as skin pigmentation changes, other skin problems, weak muscles, tiredness etc. Symptoms that can potentially be traced back to the lack of any vitamin or mineral. The protein rich foods should be your target if your body is consuming all your protein during the day, that would happen if you are constantly performing strenuous activities such as body building, swimming etc. Even then it would be kinda hard to develop a deficiency.