St. Mary's County Health Department (SMCHD) Testing. Appointment-free PCR testing; ... for patients tested at the SMCHD testing sites are available online via the Mako Medical patient portal. Patients can also sign up for text notifications at the time of testing. ... 21580 Peabody St. Leonardtown, MD 20650 Phone 301-475-4330 Fax 301-475-4350 ....