Doctors are T-shaped [0] - a GP knows a little about a lot and most have an area of interest or two that they're really well-versed in. There's just too much complexity, even within a single system, to be an up-to-date expert on everything.
For instance I have an endocrinologist (at Stanford, not to name drop but to signal this person is really good even among doctors) who only deals with thyroid. I naively figured that an endocrinologist would deal with all kinds of hormone issues but no, she's thyroid and thyroid only -- she has a colleague for testosterone, another for diabetes, etc etc.
I don't know that I'd say GPs "don't know" when to refer you; GPs are gatekeepers who will try conventional solutions to conventional problems and generally unless you push won't often suggest going deeper with a specialist. It's not that they don't know to refer you, it's that they're Level 1 Tech Support for the body and often times unless you make a stink they won't connect you to Level 2.
For instance I have an endocrinologist (at Stanford, not to name drop but to signal this person is really good even among doctors) who only deals with thyroid. I naively figured that an endocrinologist would deal with all kinds of hormone issues but no, she's thyroid and thyroid only -- she has a colleague for testosterone, another for diabetes, etc etc.
I don't know that I'd say GPs "don't know" when to refer you; GPs are gatekeepers who will try conventional solutions to conventional problems and generally unless you push won't often suggest going deeper with a specialist. It's not that they don't know to refer you, it's that they're Level 1 Tech Support for the body and often times unless you make a stink they won't connect you to Level 2.
[0] https://en.wikipedia.org/wiki/T-shaped_skills