In my experience, i do not think it is necessary to get an FNP for the "medical foundation." Prior to becoming an PMHNP, i spent about 2 years in the ER (some of which was in trauma), 4 years in critical/cardiac ICU, then about 2 years in inpatient psych hospital. After this experience, i'm pretty confident about how/when to order necessary medical workup and refer to appropriate sources. Admittedly, i went this route knowing that i was going into psych eventually and purposefully worked on these medical units for my "medical foundation." The approach to my psychiatric patients does not differ much from the approach i took when i was working those previous specialties as an RN.