What's on this Page
How is ADPKD diagnosed?
In patients older than 18 years with a family history of ADPKD, the diagnosis is primarily established by imaging studies. Patient counseling should always be done before performing imaging studies. Ultrasound is commonly used because it is noninvasive and inexpensive. Diagnostic criteria for ADPKD by ultrasound are summarized in the below table.
Ultrasound Criteria for the Diagnosis of Autosomal Dominant Polycystic Kidney Disease
CRITERIA | PKD1 | PKD2 | UNKNOWN ADPKD GENE TYPE | |
|---|---|---|---|---|
| Revised Unified Diagnostic Criteria for ADPKD | ||||
| 15–29 | ≥3 cysts, unilateral or bilateral | SEN = 94.3% | SEN = 69.5% | SEN = 81.7% |
| 30–39 | ≥3 cysts, unilateral or bilateral | SEN = 96.6% | SEN = 94.9% | SEN = 95.5% |
| 40–59 | ≥2 cysts in each kidney | SEN = 92.6% | SEN = 88.8% | SEN = 90% |
| >60 | ≥4 cysts, in each kidney | SEN = 100% | SEN = 100% | SEN = 100% |
| Revised Ultrasound Criteria for Exclusion of ADPKD | ||||
| 15–29 | ≥1 cyst | SPEC = 97.6% | SPEC = 96.6% | SPEC = 97.1% |
| 30–39 | ≥1 cyst | SPEC = 96.0% | SPEC = 93.8% | SPEC = 94.8% |
| 40–59 | ≥2 cyst | SPEC = 98.4% | SPEC = 97.8% | SPEC = 98.2% |
Note: These criteria if applied to magnetic resonance imaging or computed tomography will result in false-positive diagnoses.ADPKD , Autosomal dominant polycystic kidney disease; PKD , polycystic kidney disease; SEN , sensitivity; SPEC , specificity.
There are no preestablished diagnostic criteria for computed tomography (CT) or magnetic resonance imaging (MRI), but ultrasound criteria could reasonably be applied to CT or MRI if restricted to cysts measuring ≥1 cm in diameter. Contrast-enhanced CT and MRI provide better anatomic definition than ultrasonography and are more helpful to ascertain the severity and prognosis of the disease. In addition, both techniques are used to better characterize cystic lesions and complications. MRI is the preferred imaging modality for following disease progression in these patients. It provides great cystic-parenchyma definition without requiring intravenous (IV) contrast. CT with contrast is also highly sensitive (detects cysts as small as 3 mm), and both techniques may provide useful information regarding extrarenal manifestations of the disease (liver, pancreas, spleen, and other organs). CT with contrast should be avoided if there is evidence of significant risk of contrast nephropathy.
CT (with and without contrast) is also helpful in assessing and identifying complications, such as nephrolithiasis, complex cysts, or cyst wall calcifications from old cyst hemorrhage. Kidneys, ureter, and bladder scan and tomograms may be helpful to differentiate uric acid stones from calcium stones, whereas dual energy computed tomography may help discriminate uric acid stones from other kidney stones. Indium 111 ( 111 In) scans may be useful to identify infected kidney or liver cysts. Likewise, positron emission tomography (PET) scans may identify infected liver cysts.
Genetic testing (linkage analysis and direct DNA sequencing) is available as a clinical test and can detect PKD1 and PKD2 mutations in approximately 90% of confirmed cases. The ADPKD Mutation Database ( http://pkdb.mayo.edu ) lists known mutations of the PKD1 and PKD2 genes. Counseling should be done before genetic testing. Evaluation of family history may also provide important clues about the genetic variant, which has prognostic implications. For example, the presence of at least one affected family member who reached end-stage kidney disease (ESKD) at or before 55 years old is highly suggestive of a PKD1 mutation. Contrarily, the presence of at least one affected family member with either preserved kidney function or ESKD developed after 70 years old is highly indicative of a PKD2 mutation. Lastly, in patients with multiple bilateral cysts (10 or more per kidney) but negative family history, a presumptive diagnosis of ADPKD may be considered.
