What are kidneys?
Kidneys are vital organs, like the heart and the liver, and you cannot live without them. Most people have two kidneys, one on each side. Some people only have one kidney because the missing kidney didn’t form in infancy or was injured.
Usually, it makes little difference if you have one or two kidneys. The only real consideration is keeping the one kidney safe: no contact sports or high-risk activities like rock climbing or skydiving. Kidneys sit behind your belly where your intestines and stomach are, but in front of the big muscles in your back that allow you to stand upright. Each kidney is about the size of your fist. Like all organs, kidneys receive blood from the heart through arteries and return blood to the heart through veins.
Urine drains from each kidney to your urinary bladder through thin muscular tubes called ureters. Ureters are thin muscular tubes resembling arteries or veins, but carry urine instead of blood. Urine trickles into your bladder until the bladder is full enough that you have the urge to go to the bathroom.
What do kidneys do?
The short answer is kidneys do a lot.
- Kidneys get rid of the waste that is left over from the food that your body uses, especially the waste from metabolizing proteins.
- Kidneys also get rid of excess salt that you eat. Many Americans tend to eat too much of it; healthy kidneys dump what you do not need.
- There are other minerals your body needs besides regular table salt, sodium chloride. These include potassium (nerve conduction), calcium (bones), and magnesium (bones and teeth and many metabolic functions) and phosphorus (bones, teeth, metabolism, energy stores). Your kidneys closely regulate all of these to balance what you eat from day to day with what your body needs. It can be life-threatening if some of these minerals have concentrations in the blood that are too high or too low.
- All that water you drink has to go somewhere! Your kidneys not only get rid of the extra water, but precisely regulate the balance between salt and water.
- Kidneys regulate the acidity of your blood and body and keep this balanced.
- Blood pressure is a complicated thing. Your kidneys regulate blood pressure through controlling salt balance and by secreting hormones that affect your blood vessels. This is one reason why most kidney doctors are also asked to treat blood pressure, just as heart doctors also treat blood pressure.
- Red blood. Your blood is red because the cells that carry oxygen around your body are bright red in color. These cells are produced in your bone marrow as are most cells in your blood circulation. Your kidneys secrete the hormone erythropoetin (“eh-rith-row-poe–it-in”) that stimulates the bone marrow to make more red cells.
Who gets kidney failure, and why?
Kidney diseases affect people of all ages, genders, and ethnicities.
- In the Western industrialized world, the two most common causes of kidney failure are diabetes and high blood pressure. It is not completely clear how these diseases cause kidney failure, but there are some clues.
- Diabetics tend to have problems with all their blood vessels: feet, eyes, heart, and kidneys. The kidney is all about blood and blood vessels, so any disease that affects blood vessels will affect the kidney. High blood pressure is the same; it causes diseases in many blood vessels, including heart attacks and strokes, and kidneys are no different.
- There are a large number of autoimmune diseases that cause kidney failure. These diseases include membranous glomerulopathy, minimal change disease, focal and segmental glomerulosclerosis, membranoproliferative glomerulonephritis, and others. Lupus erythematosis and vasculitidies (inflammations of the blood vessels) are also relatively common causes of kidney disease. Cancers can also cause kidney failure.
- Many people today routinely undergo surgeries that were experimental even a few years ago, and survive infections and heart attacks that would have been fatal a generation ago. Kidneys can become stunned or injured in these extreme, life-and-death situations, and many kidneys do not recover completely.
- The kidneys are one of the ways your body eliminates drugs. Prescription and over-the-counter medicines can cause kidney failure.
- There are genetic causes of kidney failure; the most common are polycystic kidney disease and Alport’s Syndrome. In genetic diseases, the DNA code that tells your body how to assemble parts of the kidney has a mistake in it that leads to trouble. Many patients with these diseases represent new mutations in the DNA.
- Finally, blockages to the flow of urine can cause kidney disease. Men with enlarged prostates, men and woman with kidney stones, and patients who have received radiation treatments can have mechanical obstructions to the flow of urine, and the back pressure eventually causes damage to the cells of the kidney.
How can I tell if my kidneys are healthy?
There are a few red flags that should prompt you to visit your doctor as soon as possible. Blood in the urine, pink urine, dark, tea-colored urine or very foamy urine are signs of trouble. Puffy eyes or ankles can also be a sign or trouble. Any change, even gradual, in urinary habits could signal kidney troubles.
The United States Preventive Services Task Force publishes guidelines for screening patients for different sorts of diseases. Screening means looking for a disease before it causes symptoms and is hopefully at an early enough stage that treatment can avoid trouble. The National Kidney Foundation recommends prioritizing patients with chronic conditions, such as hypertension and diabetes, for screening.
If you are healthy and don’t have any special reason to worry about kidney disease, going ahead and testing you for it is unlikely to uncover a hidden disease. If you have some reason to worry, such as high blood pressure or diabetes, or a family member with kidney trouble, it may be worthwhile considering some testing and discussing with your doctor.
What can I do if my kidneys are in trouble?
First, take a deep breath and remember that most patients with kidney disease do not ever progress to having kidney failure.
Your doctor will likely send you to see a kidney specialist. The kidney specialist may order some blood and urine tests. Usually, some sort of imaging is ordered, such as an ultrasound, to show the size and shape of your kidneys. Your doctor might recommend that a kidney biopsy be performed to diagnose the cause of kidney disease.
Depending on the exact disease, your doctor may prescribe some medicines to treat the disease or slow its progression.
What will happen if my kidneys do fail?
There are many options available and many choices to make. Most patients with kidney failure choose some form of dialysis to sustain their lives. The National Kidney Foundation has terrific resources for patients and families, as does the American Association of Kidney Patients.
Dialysis
According to the American Kidney Fund, over half a million Americans rely on dialysis treatments every year to survive.
Dialysis uses a saltwater solution to clean the blood of waste products. This can happen inside the body, using peritoneal dialysis, or outside the body, using hemodialysis.
Dialysis performs some of the duties that your kidney usually does to keep your body in balance and can help prolong your life. However, it can be expensive, disruptive to daily life, and uncomfortable.
Organ donation
The best treatment for kidney failure is a new kidney. Kidney transplantation is the surgical removal of a kidney from one person and sewing it into another. Despite its low cost and great results, transplant is limited by scarcity of donor organs. The United Network for Organ Sharing publishes information and statistics about organ transplant.
In contrast to the growing number of patients with kidney disease, the number of kidney transplants has barely budged. There are now five times as many people waiting for a kidney as there are donor kidneys available. According to organdonor.gov, there are typically about 90,000 patients on the waiting list for a donor kidney and less than 30,000 kidney transplants performed per year.