Many people pay little attention to the little white moons on their fingernails. That’s unfortunate because these half moon nails, called lunulae, actually contain some insight into your overall health. If you notice some strange things going on with your fingernail moons, here’s what those things could mean.
1. Overly large lunulae could be a sign of cardiovascular trouble.
These little white moons should take up just less than a third of your fingernails. If you notice they are taking up more space than that, it could be a sign of cardiovascular trouble or an issue with low blood pressure. 
If you’re an athlete or someone who is very physically active, it’s not uncommon to have lunulae that are larger than normal. If you’re not someone in particularly good shape, there could be a problem with your blood pressure. This could also be a sign that you are overly stressed out.
2. Smaller-than-normal lunulae could be a sign of a vitamin deficiency.
If your lunulae are too small, that’s also a sign that something is off in your body. If you can barely see the lunula near your cuticle or have no moons on fingernails except thumbs, you could be lacking B12 and iron. This can also be a sign that you have a weak immune system or a problem with your leukocyte production. 
Another health problem is indicated when the lunula separates from the rest of the nail plate with transverse lines. This means you may have no moons on nails, which could be a problem with your blood sugar levels and may be an early warning sign of diabetes. Talk to your doctor to have your blood sugar checked right away.
3. Gray lunulae could be a sign of several problems.
Your lunulae should always be a distinct white. If they suddenly appear gray, this could actually be a warning sign of several different issues. 
The most serious issue that could cause gray lunulae are problems with nutrient absorption. This could be caused by a problem in the digestive system. Sometimes, however, it’s just a sign of extreme fatigue. If you notice gray lunulae after putting in long hours at work, try to find some time to relax.
4. Purple lunulae could be a sign of circulation problems.
If your lunulae are purple or blue, or if you have purple above half-moon on nails, that’s a sign that your body is having trouble getting blood to the extremities. This is turning your lunulae purple because they lack oxygen. 
You should talk to your doctor right away about this, especially if you experience dizziness or feel lightheaded. There could be something wrong with your circulatory system or your heart that needs to be corrected immediately.
5. Black lunulae are a sign that you need to see a doctor as soon as possible.
Your lunulae should never appear black. If they do, it’s a sign that there’s something seriously wrong in your body. Go to your doctor or head to the emergency room to have some testing done. 
Black lunulae can be a sign that a person has experienced heavy metal poisoning. The most common types include poisoning by lead, mercury, arsenic, or cadmium. If left untreated, this poisoning could prove fatal.
FAQs About Moons on Fingernails
Here are some final tips if you still have lingering questions about lunula and moons on fingernails.
What does it mean if I only have lunula on my thumbs?
If you only have lunula on your thumbs, this typically isn’t a cause for concern. Half moons on thumbs tend to be the most prominent and may simply mean your lunula on other fingers are hidden by skin or your cuticles.
What do moons on fingernails mean?
Moons on fingernails typically signal healthy, growing nails as the moons, or lunula are a part of the nail matrix where new cells are formed. If you have lunula, this typically signals that your nail matrix is working properly, while a lack of moons on your nails may indicate a vitamin deficiency or other health problem.
What does it mean if you’re missing half moon on nails?
Missing half moons on your nails are typically nothing to worry about but sometimes may signal various health problems ranging from vitamin deficiency to circulation issues. Contact your doctor if you experience any abnormalities or colors other than white on your nails.
Why have the half moons on my nails disappeared?
If you had moons on your nails previously and noticed they disappeared, this may be a result of trauma to a fingernail, poor circulation, or another health problem. Though before getting too concerned, ensure they haven’t been buried under excess skin at the base of your fingernail or overgrown cuticles.
