From the Research
The maximum number of kidneys a human can have is four, as reported in a rare case of bilaterally fused supernumerary kidneys 1. This condition is extremely rare and involves the presence of two extra kidneys, one on each side of the body, in addition to the two normal kidneys. The patient in this case had four fully functional kidneys, each with its own arterial supply, venous drainage, collecting system, and incompletely duplicated ureters bilaterally. Other studies have reported cases of supernumerary kidneys, but these are often rudimentary organs or have limited function 2, 3. It's worth noting that the number of nephrons, rather than the number of kidneys, is a more important factor in determining kidney function and overall health 4, 5. However, in terms of the maximum number of kidneys, the case reported in 1 is the most relevant and provides evidence of the possibility of having four kidneys. Some key points to consider include:
- Supernumerary kidneys are a rare congenital anomaly
- The presence of four fully functional kidneys is extremely rare
- The number of nephrons is a more important factor in determining kidney function and overall health
- Cases of supernumerary kidneys are often reported in the medical literature, but these are typically rare and unusual cases.