A system for the modulation of renal nerves, the system comprising: an elongated shaft including a distal portion, wherein the shaft is configured to locate the distal portion within or at least proximate to a body lumen of a human where nerves associated with sympathetic neural function are in tissue within or at least proximate the body lumen; a treatment assembly carried by the distal portion of the shaft, the treatment assembly including- a neuromodulation element configured to modulate the nerves associated with sympathetic neural function, wherein the neuromodulation element comprises at least one ablation electrode; characterized in that the system further comprises an emitter configured to produce a first diagnostic emission toward the tissue and a second diagnostic emission toward the tissue; and a detector configured to detect a parameter of return energy of the emitted energy; and a controller operably connected to the detector, the controller including memory and processing circuitry, the memory storing instructions that, when executed by the controller using the processing circuitry, cause- the controller to- detect a first parameter of return energy associated with the first diagnostic emission the first parameter of return energy including at least one of a first detection time of return energy, a first amplitude, and a first frequency, detect a second parameter of return energy associated with the second diagnostic emission, the second parameter of return energy including at least one of a second detection time of return energy, a second amplitude, and a second frequency, and determine a status of the modulation of the nerves associated with sympathetic neural function by comparing the first parameter of return energy and the second parameter of return energy. an elongated shaft including a distal portion, wherein the shaft is configured to locate the distal portion within or at least proximate to a body lumen of a human where nerves associated with sympathetic neural function are in tissue within or at least proximate the body lumen; a treatment assembly carried by the distal portion of the shaft, the treatment assembly including- a neuromodulation element configured to modulate the nerves associated with sympathetic neural function, wherein the neuromodulation element comprises at least one ablation electrode; characterized in that the system further comprises an emitter configured to produce a first diagnostic emission toward the tissue and a second diagnostic emission toward the tissue; and a detector configured to detect a parameter of return energy of the emitted energy; and a controller operably connected to the detector, the controller including memory and processing circuitry, the memory storing instructions that, when executed by the controller using the processing circuitry, cause- the controller to- detect a first parameter of return energy associated with the first diagnostic emission the first parameter of return energy including at least one of a first detection time of return energy, a first amplitude, and a first frequency, detect a second parameter of return energy associated with the second diagnostic emission, the second parameter of return energy including at least one of a second detection time of return energy, a second amplitude, and a second frequency, and determine a status of the modulation of the nerves associated with sympathetic neural function by comparing the first parameter of return energy and the second parameter of return energy. the controller to- detect a first parameter of return energy associated with the first diagnostic emission the first parameter of return energy including at least one of a first detection time of return energy, a first amplitude, and a first frequency, detect a second parameter of return energy associated with the second diagnostic emission, the second parameter of return energy including at least one of a second detection time of return energy, a second amplitude, and a second frequency, and determine a status of the modulation of the nerves associated with sympathetic neural function by comparing the first parameter of return energy and the second parameter of return energy.