“Capillary band width”, the “nail (band) sign”: A clinical marker of microvascular integrity, inflammation, cognition and age. A personal viewpoint and hypothesis

The nail provides a window of a person's wellbeing and the “nail (band) sign” provides an opportunity for the clinician to conveniently posit the state of the microcirculation of a person. Changes noted in the “capillary band” include splinter haemorrhages as an acute phenomenon. Changes in capillary band “width” and “prominence” indicate chronicity. “Capillary band width” and “prominence” may permit the differentiation of Alzheimer's from vascular causes of cognitive decline. Splinter haemorrhages and onycholysis alert clinicians to the presence of periodontal disease, and provide an indication of end organ “risk”. “Capillary band width” widening and prominence is seen in chronic smokers. Nail changes not only reflect generalised disease or inflammation but also localised peripheral conditions that affect the microcirculation. The fourth finger on the left or right hand is usually used, or the middle finger, to measure “band width”, but all fingers show the sign which is also present in the toes. Examination of “band width” and “prominence” together with other “nail signs” of wellbeing, such as the presence of the lunule at the base of the nail and smoothness of the convexity of the nail bed at its distal edge beneath the nail permit wellness evaluation and can be incorporated into standard medical practice before blood pressure measurement as a fundamental part of the clinical examination. Further evaluation will establish its importance as the most convenient yet reliable clinical sign of microvascular integrity and together with other nail signs determine its value in assessing wellness, as well as being a pointer to the presence of microvascular disease in investigative and epidemiological research and in patient management.