By Dr. Abhilash Koratala

Dr. Koratala is a clinical assistant professor in the department of medicine’s division of nephrology at the University of Florida. He is a specialist in clinical hypertension certified by the American Society of Hypertension. His clinical interests include kidney disease in pregnancy, chronic kidney disease, kidney ultrasound and hemodialysis.

1. How can it be possible to live with only one kidney? And if you have one kidney and it begins to fail, what happens?

While most people are born with two kidneys, some individuals only have one. There are three main reasons why this happens: being born with one kidney (renal agenesis); having the kidney removed (nephrectomy) due to health problems such as cancer or injury; and donating the kidney to someone with kidney failure. The remaining kidney often becomes enlarged and works harder to make up for the lost one. Generally, it should not affect the lifespan as long as that kidney is healthy.

If you have a single kidney, you should have your kidney function checked by your doctor at least once a year, keep your blood pressure under control and exercise regularly. Protecting a single kidney from injuries is very important, and you should speak with your doctor before engaging in any kind of contact sport such as football, soccer, boxing or martial arts. If the kidney begins to fail for any reason, you should see a nephrologist (kidney doctor) regularly for appropriate management, and you may be evaluated for receiving a kidney transplant and/or dialysis. Kidney failure is often silent, but symptoms such as swelling in the face or ankles, changes in urine frequency/color or a foamy appearance, nausea or vomiting, changes in the taste of food, numbness in the fingers or toes, or persistent fatigue should prompt you to seek medical attention.

2. How can you keep your kidneys healthy?

Well-being of the kidneys is very much dependent on your overall health. Maintain your blood pressure at the target set by your doctor, which for most people is less than 140/90 mm Hg. If you are a diabetic, control your blood glucose levels. Keep your cholesterol levels under control and choose a healthy diet rich in fresh fruits, fresh or frozen vegetables, whole grains and low-fat dairy foods. Remember to cut back on salt, exercise regularly and work to lose weight if you are overweight. If you are a smoker, quit smoking.

3. My co-worker had to pass a kidney stone. He was in so much pain and looked horrible. Why is passing a kidney stone so painful? Are certain people more at risk for developing them than others?

Kidney stones are often silent, but can cause pain when they start to move through the ureters (tubes carrying urine from kidneys to urinary bladder) and cause obstruction to the urine flow, sometimes causing the kidneys to swell (hydronephrosis). Ureters have muscles in their walls that try to expel the stones and sometimes go into spasm, causing severe pain. In fact, some women say the pain is worse than that of childbirth.

Yes, some people are at higher risk of developing kidney stones, such as those with a family member with stones, those who drink less water and consume more red meat, those who suffer from frequent urinary tract infections, those with bowel conditions such as ulcerative colitis and Crohn’s disease, those taking excessive supplements such as calcium and vitamin C, and those who are overweight or have rare kidney conditions such as renal tubular acidosis. If you have stones, your doctor will likely check your urine for certain chemical substances and modify treatment accordingly. Without the right medications and changes in diet, stones often come back.

4. I drink a glass of wine every day — am I at risk of hurting my kidneys? How much does alcohol consumption affect the kidneys?

Alcohol, especially when taken excessively, interferes with kidney health in various ways. It can make you dehydrated (dry you out), increase your chance of having high blood pressure and cause liver disease, all of which can hurt your kidneys. While many experts consider one drink per day for women or two drinks per day for men acceptable, the lower the alcohol consumption, the better. One standard drink is equivalent to 12 ounces of beer (5 percent alcohol content), 8 ounces of malt liquor (7 percent alcohol content), 5 ounces of wine (12 percent alcohol content) or 1.5 ounces (a shot) of 80-proof (40 percent alcohol content) distilled spirits or liquor.

5. Why is it that when you have a bladder infection your kidneys seem to hurt?

Bladder infection symptoms include an urgent need to urinate with very little amount of urine, burning while passing urine, an aching feeling in the lower abdomen, and cloudy, blood-tinged or foul smelling urine. If the infection spreads to the kidneys and becomes more severe, you may also experience pain on either side of the lower back, fever and/or chills, nausea and/or vomiting. For those who are pregnant, have uncontrolled diabetes or are taking any medications that suppress the immune system, the risk of infection spreading to the kidneys is higher and you should see your doctor as soon as you notice the initial symptoms.

6. Who is at risk for kidney disease?

Kidney disease can affect people of all ages and races, though African Americans and Hispanics particularly appear to be at greater risk of kidney failure. Diabetes, high blood pressure, heart disease, liver disease and having family members with kidney failure are well-known risk factors for kidney disease. Early kidney disease often has no symptoms, so if you have any of the above conditions, it would be wise to ask your doctor whether you should be tested for kidney disease.

*Check out the Rate Your Risk Quiz at Kidney.org to determine your risk for developing kidney disease.