The present invention provides methods and apparatus for assessing a patient's vascular health including endothelial function by monitoring changes in hemodynamic parameters responsive to the introduction of a vasostimulant. The invention provides a thermal energy measurement apparatus including a thermal energy sensor adapted to measure temperature of a body part while not substantially changing the temperature of the body part, and a display or recorder coupled to the thermal energy sensor, wherein the thermal energy sensor measures the temperature of the body part before and subsequent to the provision of a vasostimulant, and the display or recorder reports the temperature of the body part prior to the provision of the stimulant and the temperature of the body part after provision of the stimulant. Also provides are methods and apparatus providing for a second thermal energy sensor on a corresponding contralateral site to the site subject to the vasostimulant and simultaneously monitoring and recording of temperature of the contralateral site as a measure of neurovascular status and microvascular reactivity.