Understanding Nail Colour Changes and Their Implications
The colour of your nails can indicate far more than just the need for a thorough hand wash. Researchers from Rutgers Medical School in New Jersey have conducted a comprehensive analysis of various studies that highlight a curious relationship between changes in nail coloration and the potential presence of certain toxicities, cardiovascular conditions, liver diseases, as well as autoimmune and rheumatological disorders.
The majority of the studies reviewed focus on the lunula, a small, crescent-shaped area located at the base of the nail, close to the cuticle. This visible part of the nail matrix is where the nail grows and develops. Typically, this area appears as a distinct white tone, especially prominent on the thumbs and big toes. However, in rare instances, it may assume a reddish hue, which some scientific literature suggests could be correlated with various bodily alterations. The recent article published in the American Journal of the Medical Sciences posits that this phenomenon is linked to the blood vessels situated beneath the nail.
Red lunulas tend to occur when the small blood vessels dilate, leading to increased blood flow to this area. Given that the nail matrix is relatively thin and translucent, the red blood cells circulating through these dilated vessels may become more visible, imparting a reddish appearance to the lunula. This explanation could also elucidate why this sign is more readily observable in certain individuals, particularly as they age.
Historical Insights into Red Lunulas
The phenomenon of red lunulas was first documented in 1954 in London by Richard Terry, a medical researcher at St. Bartholomew’s Hospital. During his examination of 23 patients with various ailments, he discovered that 14 of them, approximately 61%, were suffering from heart failure. The remaining patients presented conditions such as emphysema, chronic bronchitis, polycythaemia vera, malnutrition, cirrhosis, lymphoma, and myeloid leukaemia. Notably, he also assessed 150 young women who appeared healthy and found no instances of red lunulas among them. This early work provided the first indication that changes in the nail base’s colour were uncommon in individuals without underlying health issues and could be associated with specific systemic diseases.
Since then, this variation has been linked with other conditions, albeit distantly related to the cardiovascular system. Among these is alopecia areata, a disorder characterised by hair loss. Some patients with this condition exhibited a reddening that replaced their normal white lunulas. Initially thought to be a consequence of corticosteroid use, subsequent observations revealed several cases of individuals with alopecia areata who did not receive such treatment yet still displayed red lunulas. This strengthened the possibility that the colour change was directly associated with the disease rather than the medication.
Connections with Rheumatological Disorders
This sign has also been observed in various rheumatological diseases. Instances have been documented in patients with rheumatoid arthritis, systemic lupus erythematosus, and dermatomyositis, among other connective tissue disorders. In a study involving 39 patients with different conditions within this group, 69% showed changes in one or more aspects of the nail unit, with one patient suffering from lupus presenting red lunulas as one of the initial manifestations of the disease.
Another investigation encompassed 190 patients, among whom 56 had systemic lupus erythematosus, 47 rheumatoid arthritis, 35 primary Sjögren’s syndrome, 39 systemic sclerosis, and 13 dermatomyositis or polymyositis. Each group included at least one patient with red lunulas, with a notably significant association observed in those with rheumatoid arthritis and primary Sjögren’s syndrome.
A Potential Early Warning Sign
The change in nail colour has also been linked to liver cirrhosis, lymphoma, psoriasis, carbon monoxide poisoning, chronic obstructive pulmonary disease, vitiligo, and nail dystrophy, in addition to certain haematological anomalies. The authors of the studies assert that “while the precise aetiology remains unclear, red lunulas may reflect both the activity of a systemic disease and a local pathology, such as subungual tumours. Given their rarity, their potential diagnostic relevance is often overlooked.”
However, they emphasise that not all changes in the colour of the nail base definitively indicate the presence of a disease. Instead, they contend that “when identifying red lunulas, healthcare providers should consider their possible relationship with an underlying systemic or dermatological condition.”
For an accurate determination of whether a lunula is indeed red, specialists recommend a thorough examination of all nails. When associated with a systemic condition, red lunulas typically appear on multiple nails in a bilateral and symmetrical fashion. Nonetheless, they reiterate that “this subtle clinical sign can aid in the early detection and identification of potentially significant systemic diseases.”