A patient presenting with a thin tongue coating is indicative of what condition?

A thin tongue coating is often indicative of a deficiency of Yin in Traditional Chinese Medicine. Yin represents the cooling, moistening aspects of the body, while its deficiency can lead to signs such as a dry mouth, night sweats, and a thin or even absence of tongue coating. When the Yin is deficient, there is not enough moisture to support the tongue's coating, resulting in a presentation that is thin and possibly pale.

In contrast, a thick tongue coating would typically suggest an excess condition, such as heatiness or phlegm retention. Cold conditions may also manifest differently on the tongue, often showing a thicker, moist coating due to the body's attempt to counterbalance cold-energies. Therefore, a thin coating predominantly points towards a Yin deficiency, making it the most suitable answer for this question.