Middle Tennessee Nephrology PLLC. Located in 270 E. Main Street, Suite 200, Gallatin, TN 37066. (615) 452-3250. Patient Portal Dr. Joseph's Patient Portal Dr. Priyadarshi's Patient Portal. Call Us: (615) 452-3250. Request More Information. Our Location. 270 E. Main Street, Suite 200 Gallatin, TN 37066..