The appearance of your fingernails says a lot about your overall health. That’s why a good physical exam should always include a careful inspection of the nails including their color, shape, texture and the presence of any irregularities. Vitamin deficiencies, anemia, liver disease and lung disease can occasionally be diagnosed based on characteristic nail abnormalities. One fingernail sign that should raise a red flag is the presence of splinter hemorrhages. What are splinter hemorrhages, and what does it mean if you have them?
What are Splinter Hemmorhages?
Splinter hemorrhages are very thin lines that run in a vertical direction underneath the nail. They are purple or black in color and usually involve discrete areas of the fingernail and don’t generally extend along the entire length of the nail. They’re usually painless and not be noticed unless you’re looking for them.
What Causes Splinter Hemorrhages?
Splinter hemorrhages occur when something damages the tiny blood vessels that feed into the nail bed. When these capillaries are damaged blood leaks out forming a small hemorrhage under the nail.
A splinter hemorrhage can form from something as simple as bumping the nail too hard. In this case, splinter hemorrhages usually involve only one fingernail, the one that was traumatized. If you have splinter hemorrhages on multiple nails, it could be a sign of a more serious medical problem.
What Types of Medical Problems Cause Splinter Hemorrhages?
The most common condition that causes these tiny hemorrhages is bacterial endocarditis. Bacterial endocarditis is a serious infection involving a heart valve. When a heart valve becomes infected, small emboli are released from the valve into the circulation. These can lodge in the capillaries causing splinter hemorrhages to form. A person with bacterial endocarditis may have other characteristic signs and symptoms such as a heart murmur, fatigue, fever and joint aches and pain.
Other medical conditions including autoimmune conditions such as systemic lupus erythematosus (SLE), scleroderma and rheumatoid arthritis can cause splinter hemorrhages too – as can inflamed blood vessels due to a condition called vasculitis.
The Bottom Line?
Splinter hemorrhages can be a sign of a serious medical problem, especially if you have many of them. If you notice tiny, dark vertical lines on your nails, see your doctor right away.
Merck Manual. Eighteenth edition. 2009.