Nurse practitioners helped fill a shortage in primary care, but they're increasingly headed to specialties

For many patients, seeing a nurse practitioner has become a routine part of primary care, in which these "NPs" often perform the same tasks that patients have relied on doctors for.

But NPs in specialty care? That's not routine, at least not yet. Increasingly, though, nurse practitioners and physician assistants are joining cardiology, dermatology and other specialty practices, broadening their skills and increasing their income.

This development worries some people who track the health workforce, because current trends suggest primary care, which has counted on nurse practitioners to backstop physician shortages, soon might not be able to rely on them to the same extent.