Doctors estimate the risk of kidney failure in autosomal dominant polycystic kidney disease (ADPKD) by combining kidney scans, blood tests over time, family history, and sometimes genetic results. Scans show how large the kidneys are for a person’s age and height; blood tests show how well they filter waste. These clues help estimate how quickly the disease may progress, but they cannot predict an exact age or outcome.
How do doctors estimate the risk of kidney failure in ADPKD?
ADPKD causes fluid-filled cysts to develop and grow in the kidneys. Over time, these cysts can enlarge the kidneys and damage their ability to filter blood. However, the rate of progression varies considerably. Some people retain good kidney function into older age, while others experience a faster decline and develop kidney failure earlier in adulthood.
Doctors therefore use several kinds of information rather than relying on a single test. The KDIGO 2025 clinical practice guideline identifies the Mayo Imaging Classification and the PROPKD score as important tools for estimating progression risk. Kidney function measurements, age, family history, and genetic findings help clinicians interpret these tools in the context of each person's medical history.
1. Kidney size and growth on imaging scans
Kidney imaging can provide useful information before routine blood tests show a clear decline in kidney function. As cysts grow, total kidney volume may increase even while the kidneys continue to filter blood reasonably well. Measuring kidney size, rather than looking only at current kidney function, can therefore help identify people who may be at greater risk of faster progression.
MRI is commonly preferred for measuring kidney volume when a formal progression assessment is needed. CT can also be used, and ultrasound may provide an alternative when MRI or CT is unavailable or unsuitable. The most useful method depends on the clinical situation, the quality of the images, and the information needed.
What is the Mayo Imaging Classification?
The Mayo Imaging Classification is a method used to estimate the likely rate of ADPKD progression from a person's age and height-adjusted total kidney volume. Height-adjusted total kidney volume means the combined volume of both kidneys considered in relation to the person's height. The classification groups people with typical ADPKD into five categories, from 1A through 1E, representing progressively faster expected kidney growth.
According to Mayo Clinic's research on predictive models in ADPKD, the classification uses age-adjusted, height-adjusted kidney volume to estimate disease progression. In general, higher classes are associated with faster kidney growth and greater concern about future loss of kidney function.
- Class 1A: Associated with the slowest expected kidney growth.
- Class 1B: Associated with relatively slow expected growth.
- Class 1C: An intermediate category that can include people with different rates of progression.
- Class 1D: Associated with faster expected kidney growth.
- Class 1E: Associated with the fastest expected kidney growth within this classification.
Classes 1C through 1E can raise concern about rapidly progressing disease, but class 1C deserves particular care in interpretation because it includes people whose disease may progress at different rates. A result near the boundary between classes 1B and 1C may also require additional review. The classification is intended for typical ADPKD kidney anatomy; people with atypical kidney shapes may not be suited to this model.
2. Changes in kidney function over time
Blood tests provide another major clue. The estimated glomerular filtration rate (eGFR) is calculated using blood test results, usually serum creatinine, along with relevant personal information. It estimates how effectively the kidneys filter waste from the blood. A lower eGFR generally indicates reduced kidney function, but one result alone cannot reliably show how quickly ADPKD is progressing.
Doctors compare repeated eGFR measurements over time to identify the pattern of change. A steady decline is more informative about long-term progression than a single low result or a temporary fluctuation. This is especially useful when kidney scans place someone near the boundary between lower- and higher-risk categories.
What rate of eGFR decline suggests faster progression?
The KDIGO 2025 ADPKD guideline uses a historical eGFR decline of at least 3 mL/min/1.73 m² per year as one indicator of rapidly progressing disease. This pattern should be established from enough measurements to assess the trend reliably, often across three to five years. It is a clinical risk indicator, not a formula that predicts a precise date when kidney failure will occur.
Doctors also check whether the decline could have another explanation. Acute kidney injury, diabetes, uncontrolled high blood pressure, and other kidney conditions can affect eGFR. A sudden drop may require prompt assessment rather than being assumed to represent the usual course of ADPKD. Identifying the cause is important before using the trend to estimate long-term risk.
3. Genetic findings and the PROPKD score
Genetic information can help explain why ADPKD progresses more quickly in some people than in others. The condition is most often associated with changes in the PKD1 or PKD2 gene. In general, PKD1-associated disease progresses more quickly than PKD2-associated disease, although the specific genetic change and other clinical factors also matter.
The PROPKD score is a clinical tool developed to estimate the risk of earlier kidney failure using a combination of genetic and clinical characteristics. The original research article, available through the National Library of Medicine's PubMed Central archive, describes a score that takes account of sex, early high blood pressure, early urinary or kidney-related events, and the type of gene change associated with ADPKD.
The score ranges from 0 to 9. Its clinical categories are low risk (0–3), intermediate risk (4–6), and high risk (7–9). A score above 6 can provide additional evidence of rapidly progressing disease, especially when imaging results or the history of eGFR decline do not give a clear answer. The score is most useful as part of a broader assessment; it should not be treated as a stand-alone prediction.
4. Family history and early clinical signs
Family history can add important context. A doctor may ask how old close relatives were when they developed substantial kidney impairment or needed dialysis or a kidney transplant. Several close relatives reaching kidney failure before age 60 can support concern about faster progression, particularly when imaging or genetic findings point in the same direction.
High blood pressure at a young age and early kidney or urinary events, such as blood in the urine or a kidney stone, may also contribute to clinical risk assessment. These details are among the factors considered by the PROPKD score. However, a relative's experience does not establish the likely outcome for another family member, and an individual event does not determine the future course of ADPKD.
Can these tests predict the exact age of kidney failure?
No current risk tool can determine the exact age at which a particular person will develop kidney failure. These methods estimate the likelihood of faster or slower progression based on patterns seen in groups of people. They are useful for planning follow-up and discussing whether additional assessment or disease-slowing treatment may be appropriate, but they cannot provide a guaranteed personal timeline.
The limitations are clinically important. A multicenter validation study indexed by the U.S. National Library of Medicine's PubMed found that the Mayo Imaging Classification generally predicted kidney outcomes but that progression varied substantially among people within the same category. This is why doctors consider the imaging classification alongside kidney function trends, genetic information, family history, and other medical conditions.
How does age affect kidney failure risk assessment?
Age matters because kidney volume and kidney function must be interpreted in relation to the person's stage of life. In adults with typical ADPKD, imaging and serial eGFR measurements are central to estimating progression risk. The Mayo Imaging Classification is designed for typical ADPKD in people aged 15–80 years; its use and interpretation depend on whether the kidney pattern fits the model.
Children and younger adolescents need an age-appropriate assessment by a clinician experienced in pediatric kidney disease. Adult risk estimates should not automatically be applied to children. For older adults, doctors also consider other health conditions that may affect kidney function, since not every decline in eGFR is caused by ADPKD itself.
How are kidney failure risk estimates used in care?
Risk assessment helps doctors decide how closely to follow kidney function, whether specialist evaluation is appropriate, and whether a discussion about disease-slowing treatment is warranted. Someone whose kidney volume suggests faster progression may need further evaluation even if the eGFR remains relatively well preserved. Conversely, a borderline or unclear imaging result may prompt a closer review of previous blood tests, family history, and genetic findings.
At an appointment, it can be helpful to bring previous creatinine and eGFR results, kidney imaging reports, a record of blood pressure measurements if available, and information about relatives who developed kidney failure. These details allow the clinician to assess the pattern over time rather than relying on one scan or blood test. The resulting estimate should be reviewed periodically as new information becomes available.