From the Guidelines
The diagnostic workup for Polycystic Kidney Disease (PKD) should begin with a thorough clinical evaluation, family history assessment, and imaging studies, with ultrasound as the initial imaging modality of choice, followed by MRI or CT scans for more detailed evaluation, as recommended by the KDIGO 2025 clinical practice guideline 1.
Diagnostic Approach
The workup for PKD involves:
- Clinical evaluation and family history assessment to identify individuals at risk
- Imaging studies, starting with ultrasound, which can detect cysts larger than 1 cm, and followed by MRI or CT scans for more detailed evaluation, as these can detect smaller cysts and provide better anatomical detail 1
- Laboratory tests, including comprehensive metabolic panel to assess kidney function (BUN, creatinine, eGFR), urinalysis to check for hematuria or proteinuria, and complete blood count
- Genetic testing, particularly for autosomal dominant PKD (ADPKD), which can identify mutations in PKD1 or PKD2 genes, and is especially valuable for diagnosis in patients with a family history but negative imaging 1
Imaging Criteria
The diagnosis of ADPKD can be confirmed by ultrasound if ≥3 total cysts are present (ages 15–39 years), ≥2 cysts are present in each kidney (ages 40–59 years), or ≥4 cysts are present in each kidney (age ≥60 years), and ruled out if ≤1 cyst is present (ages 15–39 years) or ≤2 cysts total are present (ages 40–59 years) 1. MRI criteria for diagnosis include >10 cysts total, and exclusion if <5 cysts total are present (ages 16–40 years) 1.
Genetic Testing
Genetic testing is recommended for ADPKD, particularly in cases involving few kidney cysts, variable intrafamilial disease severity, discordant imaging and glomerular filtration rate, negative family history, young living-related kidney donors at risk of ADPKD, and family planning and preimplantation diagnosis 1. The causal gene (PKD1 > PKD2 or minor genes), type of PKD1 mutation (truncating > nontruncating), sex (male > female), and environmental factors (obesity, salt intake) are associated with the severity of ADPKD 1.
Follow-up and Management
The frequency of follow-up depends on disease progression, but typically includes annual kidney function tests and blood pressure monitoring, with imaging studies every 2-3 years to track cyst growth and kidney size 1. Early diagnosis allows for timely intervention with treatments like tolvaptan, which can slow disease progression in appropriate candidates. Blood pressure measurement is crucial as hypertension is common in PKD and requires management, and screening for intracranial aneurysms with MRA may be considered in patients with family history of aneurysms or previous rupture 1.
From the Research
Diagnostic Workup for Polycystic Kidney Disease (PKD)
The diagnostic workup for PKD involves a combination of clinical evaluation, imaging studies, and genetic testing.
- The diagnosis of PKD is based on family history and radiological imaging, with ultrasound examination being the most important imaging diagnostic method 2.
- Ultrasound is highly sensitive and specific in patients over 30 years of age, and the Ravine criteria are applied to diagnose PKD 2.
- Other imaging techniques, such as computed tomography (CT) and magnetic resonance (MR), can also be used to evaluate the disease, but they are more expensive and may not be as sensitive as ultrasound in monitoring disease progression 2.
- The total renal volume is a sensitive parameter in evaluating disease progression, but its utility in monitoring individual patients has not been fully proven 2.
- Genetic testing, including whole-exome sequencing, long-range PCR, Sanger sequencing, and multiplex ligation-dependent probe amplification, can be used to identify pathogenic variations in patients with PKD, especially in those without a family history of the disease 3.
Imaging Characteristics
The imaging characteristics of PKD include:
- Multiple cysts in both kidneys, with concomitant renal enlargement 2.
- The number of large cysts, echogenicity of kidney parenchyma, cortical thickness, and presentation of cortex/medulla boundary can be assessed using grayscale ultrasound imaging 4.
- The presence and number of cysts on the kidneys, liver, and pancreas can be evaluated using abdominal sonography 5.
Clinical Evaluation
The clinical evaluation of PKD includes:
- Monitoring of glomerular filtration rate (GFR) decline, which is usually constant 2.
- Assessment of kidney function using serum creatinine concentration and creatinine clearance 4.
- Evaluation of extrarenal manifestations, such as hepatic and pancreatic cysts, which can be related to the severity of renal disease 5.