The kidneys are vital organs, which means they are essential to survival. They perform a number of functions that are necessary to keep a person healthy and alive. Some of the main functions include the following:
- Filtering waste and excess fluids from the blood
- Regulating blood pressure
- Producing hormones required to keep the bones strong and the blood healthy
- Maintaining the balance of electrolytes such as sodium, potassium, and phosphate
Most individuals are born with two kidneys, which are located below the rib cage on each side of the spine. However, sometimes people are born with only one kidney or have only one kidney that functions. When this is the case, the term “solitary kidney” is used.
The three main reasons a person may have a solitary kidney are as follows:
- Birth defect - Kidney agenesis is a condition where a baby is born with only one kidney. People born with another condition, kidney dysplasia, have two kidneys, but only one of them functions. Since a person can generally live a normal healthy life with just one kidney, people with these conditions often do not realise they have a solitary kidney until they have a test such as an X-ray or ultrasound for another reason.
- Surgical removal of a kidney - Some individuals need to have a kidney removed as a result of disease or injury. When it is removed due to cancer or another condition, the kidney and the ureter are removed.
- Kidney donation - An increasing number of people are choosing to donate a kidney for transplantation into a family member or friend who has kidney failure.
Generally, people with only one kidney can lead a healthy and full life, although it is important they maintain a healthy lifestyle to protect the kidney they do have. However, some people are at an increased risk of some kidney function loss later on in life. Some other problems can also eventually arise and they include the following:
- High blood pressure - The kidneys are involved in maintaining a healthy blood pressure by controlling the amount of fluid that flows through the blood and by producing a hormone called renin which is involved in the expansion and contraction of blood vessels. Many people with a solitary kidney develop a slightly elevated blood pressure.
- Proteinuria - this describes an excess of protein in the urine, which can indicate kidney damage. People with a solitary kidney often have above average levels of protein in their urine.
- Reduced glomerular filtration rate (GFR) - The kidneys contain millions of tiny filtering tubes called nephrons. The first part of a nephron is the glomerulus, which strains blood cells and molecules from toxins and fluids. This is referred to as the GFR and measuring it provides an indicator of how well the kidneys are functioning. People who have only one kidney often have a reduced GFR.
People with a solitary kidney should have their kidney function checked regularly, at least once a year. Healthcare providers check this with the help of simple routine urine and blood tests and blood pressure monitoring.
Reviewed by Susha Cheriyedath, MSc