29 CFR § 825.125 - Definition of health care provider.
(a) The Act defines health care provider as:
(1) A doctor of medicine or osteopathy who is authorized to practice medicine or surgery (as appropriate) by the State in which the doctor practices; or
(b) Others capable of providing health care services include only:
(1) Podiatrists, dentists, clinical psychologists, optometrists, and chiropractors (limited to treatment consisting of manual manipulation of the spine to correct a subluxation as demonstrated by X-ray to exist) authorized to practice in the State and performing within the scope of their practice as defined under State law;
(2) Nurse practitioners, nurse-midwives, clinical social workers and physician assistants who are authorized to practice under State law and who are performing within the scope of their practice as defined under State law;
(3) Christian Science Practitioners listed with the First Church of Christ, Scientist in Boston, Massachusetts. Where an employee or family member is receiving treatment from a Christian Science practitioner, an employee may not object to any requirement from an employer that the employee or family member submit to examination (though not treatment) to obtain a second or third certification from a health care provider other than a Christian Science practitioner except as otherwise provided under applicable State or local law or collective bargaining agreement;
(4) Any health care provider from whom an employer or the employer's group health plan's benefits manager will accept certification of the existence of a serious health condition to substantiate a claim for benefits; and
(5) A health care provider listed above who practices in a country other than the United States, who is authorized to practice in accordance with the law of that country, and who is performing within the scope of his or her practice as defined under such law.
(c) The phrase authorized to practice in the State as used in this section means that the provider must be authorized to diagnose and treat physical or mental health conditions.