When a person donates a kidney, the organ itself does not grow back. Instead, the remaining kidney adapts to perform the functions previously handled by two kidneys. This natural adaptation allows the donor to maintain adequate kidney function and continue living a healthy life. The process involves specific physiological changes in the remaining organ, leading to excellent long-term health outcomes with appropriate follow-up care.
How the Remaining Kidney Compensates
Kidneys do not regenerate or form a new organ after donation. However, the remaining kidney undergoes a process called compensatory hypertrophy, where it increases in size and functional capacity to handle the increased workload. This adaptation begins within days of the donation. The remaining kidney’s volume can increase by an average of about 22.4%. This growth involves both the kidney tubules and the glomeruli, which are the filtering units within the kidney.
The single kidney maintains adequate filtration and other functions. The increase in size and function of the kidney tubules and glomeruli facilitates an increase in the single nephron glomerular filtration rate (SNGFR), which is the rate at which blood is filtered by individual nephrons. This compensatory hyperfiltration helps normalize the overall glomerular filtration rate (GFR), ensuring that the body effectively filters waste products and maintains fluid and electrolyte balance. While the exact mechanisms driving this growth are not fully understood, increased activity by the remaining kidney and the release of kidney-specific factors are thought to play a role.
Life After Kidney Donation
Individuals who have donated a kidney generally experience excellent long-term health, leading normal, healthy lives. Living kidney donors are carefully selected and undergo thorough health screenings before donation, contributing to favorable long-term outcomes. Some studies suggest that living donors may live longer than the average person due to their initial healthy status.
Regular medical follow-ups are important after donation to ensure ongoing kidney health. Transplant centers monitor donors for at least two years post-surgery, with recommended visits to check for protein in the urine, measure blood pressure, and assess kidney function through blood tests. After the initial two years, annual follow-ups with a primary care physician are recommended to continue monitoring these health indicators.
While most donors maintain good health, there are rare potential long-term risks. Some donors may experience a slight increase in blood pressure years after donation, often managed with medication. There is also a small chance of developing mild chronic kidney disease or, in less than 1% of cases, kidney failure. Female donors may also have a slightly higher risk of gestational hypertension and preeclampsia in pregnancies after donation. These potential risks are managed through ongoing monitoring and lifestyle recommendations.
Donors can resume normal activities within a few months after surgery and typically do not need to make major changes to their diet or lifestyle. Maintaining a healthy diet, engaging in regular exercise, and avoiding substances harmful to kidneys, such as certain non-steroidal anti-inflammatory drugs (NSAIDs), are recommended. Avoiding high-impact sports where the remaining kidney could be at risk is also advised, or wearing protective padding if participating.