The main function of your kidneys is to filter your blood and remove extra fluids and waste through urine. Healthy kidneys keep the right balance of water, salt, and minerals. They also help nerves, muscles, and other parts of your body work well. Kidneys make hormones that control blood pressure, make red blood cells, and keep bones strong. 

Kidney Disease 
Kidney disease occurs when your kidneys cannot filter blood properly and waste builds up in your body. This condition usually develops slowly, and many people do not know they have it because early stages often have no symptoms. 

In the later stages, kidney disease can cause: 

• Feeling tired, trouble sleeping, or trouble focusing 

• Dark, pale, dry, or itchy skin 

• Changes in urination – more or less than usual, foamy or bloody urine 

• Swelling in ankles, legs, feet, or around the eyes 

• Muscle cramps or spasms 

• Headaches or chest pain 

• Shortness of breath, frequent hiccups, or bad breath 

• Loss of appetite, nausea, vomiting, or weight loss 

• Missed periods or problems with sexual activity 

You may be at higher risk if you: 

• Have diabetes or high blood pressure (the main causes of kidney disease) 

• Have a family member with kidney disease 

• Have heart disease 

• Are 60 years or older 

• Have taken medicines that can damage the kidneys 

How to keep your kidneys healthy: 

• Talk to your doctor and get blood and urine tests at least once a year 

• Eat healthy foods: fruits, vegetables, whole grains, low-fat or fat-free dairy, lean proteins, and foods low in salt, bad fats, and added sugar 

• Drink water throughout the day, especially with meals 

• Get at least 30 minutes of physical activity every day 

• Maintain a healthy weight 

• Sleep 7–9 hours every day 

• Do not smoke and limit alcohol consumption 

• Manage stress and do activities that help you relax 

• Keep diabetes, high blood pressure, or heart disease under control 

• Take your medicines exactly as prescribed by your doctor 

References: 
https://www.niddk.nih.gov/health-information/kidney-disease  
https://medlineplus.gov/kidneydiseases.html