Kidneys are about the size of a fist; they are located underneath the ribcage and deep in the upper abdominal cavity. Two blood vessels — the renal artery and renal vein — and the ureter connect to the kidney in the middle; they form an indentation (the hilus) to make the organ look like a bean.
How Do Kidneys Work?
Each kidney contains a million tiny filtering units called nephrons; in each nephron, there is another filtering unit called the glomerulus that is made up of small blood capillaries. When blood enters the kidneys through the renal arteries, waste products from metabolism and excess salt (sodium) and water are filtered and removed as urine through the ureters. Healthy red blood cells, minerals and proteins are retained in the blood and exit through the renal veins.
Kidneys are akin to a wastewater treatment plant. They regulate the water and chemical balance, convert vitamin D to an active form that is vital to bone health, and produce a hormone that creates red blood cells.
How Does Aging Affect the Function of the Kidneys?
As we age, the number of nephrons in our kidneys decreases, as does the amount of kidney tissue; our blood vessels become thicker; and blood flow slows down. All of these factors contribute to a gradual decline in our kidney function.
Seniors should have a physical from their primary care physician every six or 12 months to maintain general health. In particular, those with high blood pressure, heart disease, diabetes, a family history of kidney disease, or weight issues should get tested annually, as these health conditions pose higher risks of kidney problems.
What Questions Do People Ask Nephrologists?
Nephrologists are internal medicine doctors who specialize in diagnosing and treating kidney diseases. Below are 10 common questions they hear from patients.
1. How would I know if I have a kidney disease?
Since the kidneys purify and keep nutrients in the blood, then dispose of waste through urine, both blood and urine tests can reveal if you have a kidney disease.
2. I don’t have any pain. How can I have a kidney problem?
Symptoms of kidney diseases may not show right away. As the number of nephrons in each kidney can be as many as a million, you may not notice issues even if your kidneys are functioning at only 10% of their capacity 1.
3. What are the common causes of kidney diseases?
High blood pressure, diabetes and obesity are the most common causes of kidney diseases.
High blood pressure damages the tiny blood vessels and filtering units in the kidneys, reducing the kidneys’ capacity to remove excess water and waste from the blood.
People with diabetes have high levels of blood glucose, which is harmful to the blood vessels in the kidneys. According to the Mayo Clinic, one in four patients with diabetes develops kidney disease eventually 2.
As for individuals with obesity, they are more vulnerable to developing high blood pressure and diabetes, as well as kidney diseases.
4. I have had high blood pressure for a long time — is that normal?
Blood pressure at <120/80 mm Hg is considered normal. A reading of 120-129 mm Hg systolic and greater than 80 mm Hg diastolic is considered high. An individual with a blood pressure of 130 mm Hg systolic or 80-89 mm Hg diastolic has hypertension and is more vulnerable to have heart disease and stroke 3.
Although high blood pressure is relatively common, chronic high blood pressure is dangerous. Artery walls exposed continuously to strong forces of blood pushing through stiffen. The hardening of the arteries will force the heart to pump harder so blood can circulate through the body. Organs may not receive sufficient blood and nutrients to function at full capacity. And in the kidneys’ case, insufficient blood will cause accumulation of toxins in the body.
5. What are the symptoms of kidney disease?
Kidney disease may decrease the number of red blood cells, causing anemia, which means fewer red blood cells are available to deliver oxygen to fuel the body. You may, therefore, feel more tired or have a hard time concentrating.
When the kidneys cannot filter waste products and retain nutrients properly, protein and blood may “leak” into the urine. If your urine is foamy, it may indicate that there is protein in it 4.
6. How does kidney disease cause anemia?
Kidney disease or damage can be the cause of anemia. Anemia means that the body does not have enough red blood cells to transport oxygen throughout the body. The kidneys create a hormone called erythropoietin (EPO), 5 which produces red blood cells. Damaged kidneys may not generate this hormone, resulting in fewer red blood cells to deliver oxygen.
7. What drugs are harmful to the kidneys?
All drugs pass through the kidneys. In particular, pain medications, antibiotics, prescription laxatives and contrast dye can reduce blood flow to the organs. Make sure you follow the instructions of your healthcare provider to prevent injury to the kidneys.
Alcohol and illegal substances can hurt the kidneys, as well.
8. How can I protect my kidneys if I take medicines to treat a health condition?
If you have chronic pain, consult a doctor and do not use over-the-counter pain relievers for more than 10 days. The same is true if you have a fever for more than three days.
Avoid prolonged use of analgesics that contain a mixture of ingredients like aspirin, acetaminophen and caffeine in one pill. If you are taking analgesics, avoid drinking alcohol and increase the amount of fluid you drink to six to eight glasses per day. Consult your doctor before taking painkillers such as nonsteroidal anti-inflammatory drugs (NSAIDs) or higher-dose aspirin if you have any kidney disease.
Make sure that your doctor is aware of all the medicines you are taking, including over-the-counter medications. Getting blood tests during an annual physical may also assist your provider in determining if you have kidney disease 6.
9. What foods should I avoid for my kidney health?
If you have kidney disease, consult with a renal dietitian for advice on how to support your nutritional needs. But in general, avoid foods that are high in sodium. Too much sodium can cause high blood pressure and therefore bad for your kidneys. When the kidneys cannot remove excess salt and fluid from the body, you may see swelling in your legs and around your eyes.
Physicians may advise people with kidney disease to restrict the intake of potassium and protein, as they both put more pressure on the kidneys to process.
10. How does my doctor know I need to have dialysis or get a transplant?
Most people do not know that kidney function can be assessed with a simple blood test. Chances are you have had your kidney function tested during routine blood work. Kidney disease has no symptoms until it is advanced, so ask your doctor what your kidney function is. If you have diabetes or hypertension or a family history of kidney disease, be sure to get your kidney health tested. Be proactive and protect your kidney health.
March Is National Kidney Month
Eighty million (or one in three) Americans are estimated to be at risk of having kidney disease 7, yet not many are aware of it. Because kidney disease does not always manifest symptoms, some patients only find out when their kidneys are failing. To raise awareness for how prevalent kidney disease is, the National Kidney Foundation (NKF) is launching a yearlong campaign, “ Are you the 33%,” beginning in March. As part of this initiative, a one-minute quiz for individuals to evaluate their risks of kidney disease is available on a dedicated microsite, MinuteForYourKidneys.org.
Photo courtesy of National Kidney Foundation
Learning your risks of kidney disease may potentially save your life. Take a minute to finish the quiz!
1 Hoffman, M. (August 07, 2019). Picture of the Kidneys. Retrieved from https://www.webmd.com/kidney-stones/picture-of-the-kidneys#1
2 Mayo Clinic. (n/a). Diabetic nephropathy. Retrieved from https://www.mayoclinic.org/diseases-conditions/diabetic-nephropathy/symptoms-causes/syc-20354556
3 Healthline. (n/a). Blood Pressure Readings Explained. Retrieved from https://www.healthline.com/health/high-blood-pressure-hypertension/blood-pressure-reading-explained
4 The National Kidney Foundation. (n/a). 10 Signs You May Have Kidney Disease. Retrieved from https://www.kidney.org/news/ekidney/august14/10_Signs_You_May_Have_Kidney_Disease
5 Cleveland Clinic. (February 2, 2018). Erythropoietin-Stimulating Agents. Retrieved from https://my.clevelandclinic.org/health/drugs/14573-erythropoietin-stimulating-agents
6 Kubala, J. (November 18, 2019). The 20 Best Foods for People with Kidney Disease. Retrieved from https://www.healthline.com/nutrition/best-foods-for-kidneys#1
7 National Kidney Foundation. (n/a). Kidney Disease: The Basics. Retrieved from https://www.kidney.org/news/newsroom/factsheets/KidneyDiseaseBasics