Regarding information sharing, not quite. Covered entities (term of art in HIPAA), which include providers (and also payers!) including both the lab and your do

Regarding information sharing, not quite. Covered entities (term of art in HIPAA), which include providers (and also payers!) including both the lab and your doctor, do not need your permission to share information between them for the purposes of treatment, payment, or operations (commonly, "TPO"). A BAA between a covered entity and a vendor (like an EHR or PACS [viewer for your imaging]) also does not require any patient consent. There are sometimes things you might not like hidden in the releases you're signing, beyond the run of the mill acceptance of financial responsibility / assignment of benefits, notice of privacy policy acknowledgment, consent to treat.