To give you an idea of how important the kidneys are, consider that all the blood in your body passes through your kidneys approximately 40 times a day, filtered by about one million tiny units called nephrons. The kidneys are located under your ribcage, so it might surprise you to find out that problems can manifest in your hands. Read on to find out what signs to watch for, and when to see your doctor. READ THIS NEXT: If You Notice This in Your Mouth, Get Your Kidneys Checked. “Swelling of the hands can be caused by a number of things,” says O’Flynn. “Obviously an injury like a fracture of a bone, sprain, or dislocation can lead to swelling, as can arthritis.” But swollen hands can also be caused by kidney problems. Because kidneys filter waste from the blood and then produce urine, “when the kidneys aren’t doing their job, this fluid can stay in the system instead of being excreted,” explains the National Kidney Foundation. This buildup of fluid may result in swelling of the fingers and hands, as well as in the feet and ankles. If you see swelling in these extremities, especially with other symptoms of kidney problems, you should talk to your doctor. ae0fcc31ae342fd3a1346ebb1f342fcb Your fingernails (and toenails, too) can tell you a lot about what’s going on with various aspects of your health, including heart problems, diabetes, thyroid disease, and even cancer. According to the American Academy of Dermatology Association (AADA), there are several signs of kidney problems that can manifest in the nails. These include “a white color on the upper part of one or more nails and a normal to reddish brown color below (half-and-half nails); pale nails; and white bands running across one or more nails (Muehrcke’s nails).” Why does kidney disease lead to changes in nails? The kidneys usually filter out nitrogen waste; when they’re unable to do so, the waste accumulates and causes changes in the appearance of fingernails and toenails. RELATED: For more up-to-date information, sign up for our daily newsletter. A surprising sign of kidney disease can be dry, itchy skin (also called pruritis), caused by an imbalance of minerals. As the AADA explains, “Dry and itchy skin can be a sign of the mineral and bone disease that often accompanies advanced kidney disease, when the kidneys are no longer able to keep the right balance of minerals and nutrients in your blood.” Dry and itchy hands can signal other potential problems, of course, including dehydration and using too much hand sanitizer. If it occurs with other signs of kidney disease, such as the frequent urge to urinate, the two may be related. “When the filters found within the kidneys become damaged, it can actually cause an increase in the feeling that someone needs to urinate,” says O’Flynn. “There may be a significant increase in the pressure felt when urinating, and the urine itself may start to change, appearing more foamy or even bubbly. This suggests an increase in the protein found in urine, which is an indicator of larger kidney issues.” Kidney problems can lead to changes in the color of skin on the hands and other parts of the body. “When the kidneys stop working as they should, toxins build up in your body. This build-up can cause color changes to the skin,” explains the the AADA, which cites the following possible changes in color: an unhealthy pale color, grayish, yellowish, or darkened skin, as well as “thick skin with bumps and deep lines.” In addition, cysts and whitehead-like spots can appear after extended periods of scratching itchy skin. If you notice any of these signs in your hands, speak with your doctor about whether they could indicate kidney trouble. READ THIS NEXT: If You Notice This on Your Face, Have Your Kidneys Checked.