Removing a kidney triggers an immediate drop in your overall glomerular filtration rate, followed by a compensatory rise as the remaining kidney enlarges and increases its workload. In most healthy people, that single remaining kidney eventually recovers to roughly 70–80% of the pre-surgery two-kidney GFR, and this level can remain stable for decades. How much function you recover, how fast it happens, and whether you face problems down the road depend on whether the surgery was radical or partial, your age, your baseline health, and a handful of other factors that are worth understanding before or after surgery.
The Immediate Drop and Early Recovery
Within the first days after nephrectomy, your GFR falls substantially. You have just lost half your filtering tissue, so this is expected. A multi-center study tracking patients after radical nephrectomy confirmed that everyone experienced a clear drop in eGFR right after surgery, regardless of their starting kidney function.1PubMed Central. Long-term renal functional recovery following radical nephrectomy for kidney cancer: Results from a multi-center confirmatory study What comes next depends partly on how much kidney tissue was removed and how healthy the remaining kidney is.
For partial nephrectomy, where only the tumor and a margin of tissue are taken out, recovery is faster and the GFR loss is smaller. Research on patients who underwent minimally invasive partial nephrectomy found that by six to twelve weeks after surgery, preserved eGFR was about 92% of the preoperative value, and the function of the operated kidney itself had recovered to about 77% of its baseline by that same time frame. That six-to-twelve-week mark was not significantly different from the one-year mark, suggesting most of the early recovery happens in the first couple of months.2PubMed. Assessing Time of Full Renal Recovery Following Minimally Invasive Partial Nephrectomy
How the Remaining Kidney Compensates
The recovery you see in GFR after losing a kidney is not just the remaining kidney working at its same capacity. It physically adapts. The remaining kidney grows larger through a process called compensatory hypertrophy, and its filtering units ramp up their individual output through hyperfiltration. These two mechanisms work together, and researchers have spent decades sorting out the molecular details.
At the level of the individual filtering unit, the kidney increases its single-nephron GFR by widening the filtration surface and pushing more fluid through each glomerulus. Modeling studies in both younger and older adults who had one kidney removed showed that the remaining kidney achieves hyperfiltration through increases in the ultrafiltration coefficient (essentially, filtering surface area) or through small increases in the pressure gradient driving filtration, or some combination of both. The magnitude of this adaptive response was similar in older and younger people, though older adults started at a lower absolute GFR.3PubMed. Adaptive hyperfiltration in the aging kidney after contralateral nephrectomy
The growth side of the equation involves actual enlargement of the kidney’s tubular cells. Research using a mouse model of unilateral nephrectomy identified a lipid-activated transcription factor called PPARα as a key driver of this compensatory hypertrophy. When researchers deleted PPARα genetically, the remaining kidney was substantially smaller after nephrectomy and its tubular cells had clearly reduced volume, confirming that PPARα is an important molecular switch controlling how much the kidney can grow in response to losing its partner.4PubMed Central. Signaling mechanisms in renal compensatory hypertrophy revealed by multi-omics
Growth factors produced locally in the kidney also play a role. Within 24 hours of nephrectomy in animal models, levels of insulin-like growth factor I (IGF-I) messenger RNA in the remaining kidney jumped five- to six-fold compared to controls, and this increase persisted for at least seven days. The IGF-I induction was specific to the kidney undergoing compensatory growth and was not driven by changes in growth hormone levels in the blood, indicating it is a local, tissue-level response rather than something orchestrated from the brain.5PubMed. Relative increase in insulin-like growth factor I messenger ribonucleic acid levels in compensatory renal hypertrophy
Where GFR Settles in the Long Run
For kidney donors, who represent the healthiest population undergoing nephrectomy, the remaining kidney’s measured GFR increased by about 29% at two months and 35% at six months compared to its pre-donation function.6PubMed. Preserved Kidney Function and Renal Recovery in Living Kidney Donors That single kidney is doing considerably more work than it did before, but it still cannot fully replace the lost kidney’s contribution. The net result is a total GFR that stabilizes at roughly two-thirds to three-quarters of the original two-kidney value.
The timing of stabilization matters for setting expectations. A study of living donors found that there was no significant difference in eGFR between one month and three, six, or twelve months after surgery, suggesting that most of the functional recovery is already in place by the first postoperative month. Donors who had mildly reduced kidney function before surgery (falling into chronic kidney disease staging) initially lagged behind donors with normal baseline function, but by twelve months their percent recovery had caught up and was indistinguishable from the healthier group.7PubMed. Clinical assessment of renal function stabilization after living donor nephrectomy
Patients who started with a preoperative eGFR above 60 tended to show a flat, stable trajectory after the initial drop. Those who started below 60 actually showed a slight upward trend over time, meaning the remaining kidney continued to improve its filtration gradually.1PubMed Central. Long-term renal functional recovery following radical nephrectomy for kidney cancer: Results from a multi-center confirmatory study Over periods of two decades and longer, studies of kidney donors have found that the compensatory GFR elevation remains stable, holding at about 70–80% of normal two-kidney GFR without progressive decline.
Partial Versus Radical Nephrectomy
The amount of kidney tissue you keep makes a real difference. In a comparison of partial and radical nephrectomy for kidney cancer, the mean eGFR one year after surgery was about 71 mL/min/1.73 m² in the partial group versus roughly 52 mL/min/1.73 m² in the radical group.8PubMed Central. Partial vs. radical nephrectomy and the risk of all-cause mortality, cardiovascular, and nephrological outcomes That gap is meaningful because an eGFR in the low 50s puts you into stage 3 chronic kidney disease territory, while the low 70s is closer to normal aging kidney function. This is one of the main reasons surgeons prefer partial nephrectomy whenever the tumor’s size and location make it feasible.
For partial nephrectomy specifically, the duration of reduced blood flow to the kidney during surgery (called ischemia time) also influences recovery. A meta-analysis found that longer warm ischemia time was associated with lower postoperative eGFR.9PubMed Central. The impact of warm ischemia time on short-term renal function after partial nephrectomy: a systematic review and meta-analysis However, the effect per minute of ischemia may be smaller than people fear. One study found that each additional ten minutes of warm ischemia was associated with only about a 2.5% decline in recovery, and that cooling the kidney (cold ischemia) led to consistently better functional recovery, with a median of 99% recovery from ischemia compared to 92% with warm ischemia.10PubMed. Ischemia and Functional Recovery from Partial Nephrectomy: Refined Perspectives So while surgeons rightly try to minimize ischemia time, a few extra minutes are not catastrophic for most patients.
How Age, Diabetes, and Hypertension Affect Recovery
Not everyone’s remaining kidney compensates equally. A study of living kidney donors found that older age and higher preoperative HbA1c (a marker of blood sugar control) were independent risk factors for worse eGFR at six months. The effect of age was stronger in female donors, while poor blood sugar control had a greater impact in male donors.11International Urology and Nephrology. Age and Pre-operative HbA1c levels affect renal function compensation in living kidney donors
For patients undergoing nephrectomy for cancer, the picture is a bit more complicated. One study found that patients with both hypertension and diabetes had about a 36% reduction in postoperative GFR, compared to a 23% reduction in patients who had neither condition. Having hypertension alone produced a 32% reduction. These differences persisted at three to twelve months of follow-up.12PubMed. The effect of hypertension and diabetes on the degree of renal function deterioration after unilateral nephrectomy Another study confirmed that the eGFR decline in patients with hypertension or diabetes was significantly larger than in those without these conditions.13PubMed. Change in renal function post-nephrectomy for renal cell carcinoma in patients with and without hypertension and/or diabetes
That said, the story is not entirely pessimistic for people with these conditions. A study of patients who had normal baseline kidney function before partial nephrectomy found that while hypertension and diabetes were associated with a slightly steeper initial GFR drop, the predicted eGFR for both groups converged to about 83 mL/min/1.73 m² by 24 months, and the difference in trajectory was not statistically significant.14PubMed. Hypertension and diabetes mellitus are not associated with worse renal functional outcome after partial nephrectomy in patients with normal baseline kidney function The takeaway is that having these conditions matters more when the starting kidney function is already compromised, or when the entire kidney is removed rather than just a portion.
The Downside of Hyperfiltration
The compensatory hyperfiltration that rescues your GFR in the short term has a potential dark side. When each filtering unit works harder for years and decades, the increased pressure and flow can slowly damage the glomeruli. This has been linked to the development of proteinuria (protein leaking into the urine), hypertension, and gradual further loss of kidney function in some patients with solitary kidneys.15PubMed Central. Hyperfiltration-mediated Injury in the Remaining Kidney of a Transplant Donor
An early study of kidney donors found that male donors had a higher incidence of both proteinuria and hypertension compared to their pre-surgery values and to matched controls. Female donors also developed increased proteinuria, though the changes were described as mild.16PubMed. Hypertension and proteinuria: long-term sequelae of uninephrectomy in humans In more severe cases, chronic hyperfiltration has been proposed as the mechanism behind focal glomerulosclerosis (scarring of the filtering units) in people with a solitary kidney.17PubMed. Focal glomerulosclerosis and proteinuria in patients with solitary kidneys
Despite these risks, the absolute probability of serious kidney failure remains low for most donors. A large study estimated that the risk of end-stage renal disease at 15 years after donation was about 31 per 10,000 donors, compared to roughly 4 per 10,000 in matched healthy non-donors. The estimated lifetime risk was about 90 per 10,000 donors, which is substantially lower than the 326 per 10,000 seen in the general unscreened population.18PubMed Central. Risk of end-stage renal disease following live kidney donation In other words, donating a kidney does measurably increase your risk of end-stage kidney disease compared to a perfectly healthy matched non-donor, but your risk is still far lower than the average person’s, because donors are carefully screened for baseline health.
Children and Congenital Solitary Kidneys
Children who lose a kidney face a somewhat different situation than adults. Their remaining kidney has more growth potential, but they also have more decades ahead during which hyperfiltration-related damage could accumulate. A systematic review and meta-analysis of children after unilateral nephrectomy found that signs of kidney injury were present in a meaningful proportion: about 15% had proteinuria, about 15% had hypertension, and roughly 12% had a decreased eGFR.19PubMed Central. Kidney injury rates after unilateral nephrectomy in childhood—a systematic review and meta-analysis
A study following the natural history of solitary kidneys in a pediatric population found that about 22% of children showed GFR deterioration over an average follow-up of about three and a half years, and nearly 44% developed some type of new kidney injury after nephrectomy.20PubMed Central. The natural history of solitary post-nephrectomy kidney in a pediatric population These numbers argue for long-term monitoring in children with a solitary kidney, even when the initial compensation looks successful.
Pregnancy With a Single Kidney
Pregnancy is a natural stress test for the kidneys. Blood volume increases, GFR rises by 40–50% in a normal two-kidney pregnancy, and the kidneys have to handle a substantially higher workload. Women with a solitary kidney face this challenge with less reserve. A study comparing pregnant women who had a solitary kidney to matched controls found significantly higher rates of gestational hypertension, preeclampsia, and need for maternal intensive care. The analysis showed roughly a seven-fold increase in preterm labor risk and a three-fold increase in preeclampsia risk among women with a solitary kidney.21Journal of Pediatric Urology. Pregnancy outcomes in women with a maternal solitary kidney These are meaningful risks that deserve a conversation with both a nephrologist and an obstetrician before or early in pregnancy.
Measuring GFR After Nephrectomy Can Be Tricky
One practical issue that often goes unmentioned is that the standard blood tests used to estimate GFR were developed and validated in people with two kidneys. After nephrectomy, these equations can behave unexpectedly. Creatinine, the most common blood marker used to calculate eGFR, does not always track kidney function changes smoothly after surgery. Research has found that in certain ranges, creatinine can plateau even while actual kidney function is changing, creating a blind spot for detecting early impairment. Cystatin C, an alternative blood marker, appeared to detect postoperative kidney function changes more sensitively in some of those ranges.22PubMed Central. Cystatin C predicts renal function impairment after partial or radical tumor nephrectomy
However, the advantage of cystatin C is not universal. A study specifically evaluating cystatin C in kidney donors found that it performed similarly to traditional creatinine-based measures for both preoperative assessment and post-donation monitoring.23PubMed. Serum cystatin C performs similarly to traditional markers of kidney function in the evaluation of donor kidney function prior to and following unilateral nephrectomy The practical point for patients is that a single eGFR reading after nephrectomy may not tell the whole story, and trending the value over time is more useful than fixating on any one number.
Medications That Interact With Post-Nephrectomy Kidney Function
Once you are living with a solitary kidney, the medications you take for other conditions can influence your GFR trajectory. Drugs that block the renin-angiotensin system, such as ACE inhibitors and angiotensin receptor blockers (ARBs), are commonly used to protect the kidneys by reducing the pressure within the glomeruli. A newer class of drugs, SGLT2 inhibitors, originally developed for diabetes, has also shown kidney-protective effects through different mechanisms.
A study of combination therapy with an SGLT2 inhibitor and an ACE inhibitor found that the combination lowered GFR by about 8 mL/min/1.73 m² compared to the ACE inhibitor alone. This dip is not a sign of damage. It reflects reduced pressure inside the glomeruli, which is the intended protective effect. The combination also reduced markers of oxidative stress in the kidneys.24PubMed Central. Renal and Vascular Effects of Combined SGLT2 and Angiotensin-Converting Enzyme Inhibition This is worth knowing because if you start one of these medications after nephrectomy and your eGFR drops a few points, that is often the drug doing what it is supposed to do rather than your kidney getting worse. Your doctor will typically recheck at a few weeks and look for stabilization rather than continuing decline.