When you notice changes to your nails, they’re usually a result of environmental factors. For example, they might be damaged by harsh cleaners, excessive typing, or using a lot of products that dry out the nails and cuticles. However, according to the American Academy of Dermatology, there are some alterations in your nails that warrant close attention, as they may be signs of serious health conditions.

1. Anemia

In a condition known as koilonychia (or “spoon nails”), the fingernails become soft and bent. They appear scooped out in the center, often forming a depression deep enough to hold a drop of water. This is usually a sign of iron deficiency anemia. Pale nail beds and cuticles are additional indications of low iron in the blood.

2. Liver health

Koilonychia can also be a sign of a liver condition known as hemochromatosis, which occurs when your body absorbs too much iron from the food you eat and is forced to store the excess mineral in your liver and other organs. The liver disease sometimes presents with pale or white nails as well.

Also Read: Osteoporosis: The Hidden Disease That Affects Millions

Since koilonychia can be caused by either too much or too little iron, it is important to consult a doctor to find out the exact cause of the condition.

3. Respiratory health

If your nail beds take on a blueish tinge, it usually signals a lack of oxygen in your blood—often an indication of respiratory conditions such as emphysema. Another sign of respiratory disease is yellow nail syndrome, which causes nails to become thick and yellow. Often, this syndrome will cause the growth of nails to slow or stop entirely.

4. Heart health

A blue tint to the nails can also be a sign of heart disease, which can prevent blood from circulating oxygen properly through the body. Heart disease can also cause Terry’s nails, a condition in which the nails become pale and opaque (except for a pinkish band at the very tips).

5. Lung disease

Usually, nails extend straight out from the tops of fingers. But in some instances, a condition known as nail clubbing occurs. This is when the tips of the fingers become enlarged over the course of several years, and the nail begins to curve over the fingertip. Nail clubbing is usually a sign of poor oxygen levels in the blood and could be an indication that you suffer from a form of lung disease. Other signs of lung disease include yellowing and thickening of the nails.

6. Diabetes

Finally, diabetes can affect your nails in one of two common ways. Sometimes, the nails become yellow or brownish, except for a little pink at the very base where the nail meets the cuticle. In other instances, those with diabetes see a nail condition known as Beau’s lines, in which indentations appear in the middle of the nail. This change develops because diabetes interrupts the growth of the nail under the cuticle, causing a dent to appear as the nail grows out.