A person can indeed have three kidneys, a rare but documented reality. This unusual circumstance typically arises in one of two distinct ways: either an individual is born with an extra kidney due to a developmental anomaly, or a third kidney is acquired through life-saving medical intervention, specifically a kidney transplant. Both scenarios highlight the remarkable adaptability of the human body and the advancements in modern medicine.
Supernumerary Kidneys
Being born with an extra kidney, known as a supernumerary kidney, is a rare congenital anomaly. Medical literature reports fewer than 100 to 200 such cases worldwide. A supernumerary kidney is a distinct, fully or partially formed organ, with its own encapsulated tissue, blood supply, and collecting system, separate from the two typical kidneys. It develops during the embryonic stage, believed to result from an abnormal splitting or duplication of the nephrogenic cord or ureteric bud, the structures that form the kidneys.
This extra kidney is often smaller than a native kidney and typically located lower or on the same side as one of the existing kidneys. Many individuals with a supernumerary kidney remain unaware of its presence throughout their lives, as it often functions normally and causes no symptoms. Its discovery is usually incidental, occurring during imaging studies performed for unrelated medical reasons. However, if complications such as hydronephrosis, kidney stones, or infections arise, symptoms like pain or a palpable abdominal mass may lead to its diagnosis.
Kidney Transplantation
Another way a person can have three kidneys is through kidney transplantation. When a patient receives a new kidney for end-stage renal disease, their original, diseased kidneys are not usually removed. Removing the native kidneys is a complex surgical procedure with additional risks, and it is typically performed only if they cause severe issues. These issues include uncontrolled high blood pressure, recurring infections, or significant enlargement due to conditions such as polycystic kidney disease.
The transplanted kidney is placed in a different location than the original kidneys, usually in the lower abdomen or pelvis. Surgeons connect the new kidney’s blood vessels to the recipient’s major arteries and veins in the lower abdomen, often the external iliac artery and vein. The ureter of the transplanted kidney is then connected directly to the bladder. This approach allows the new kidney to function effectively without disturbing the native kidneys.
Living with Three Kidneys
Individuals living with three kidneys, whether congenitally or after a transplant, typically adapt well. In cases of supernumerary kidneys, if healthy and without complications, it often functions alongside the other two without causing any adverse health effects. The body’s overall filtration capacity may be enhanced, but one healthy kidney is typically sufficient to maintain bodily functions.
For transplant recipients, the new, healthy kidney takes on the primary role of filtering waste and regulating fluids, restoring kidney function. The two native kidneys, even if non-functional, usually do not impede the transplanted kidney’s performance. Regular monitoring of kidney function, blood pressure, and general health is important for all individuals with three kidneys, especially transplant recipients, to manage potential complications.