Diagnosis of Polycystic Kidney Disease
Patients with polycystic kidney disease (PKD) can present with hypertension, hematuria, proteinuria, or renal insufficiency. These can be discovered by routine laboratory urinalysis and blood work:
- CMP (complete metabolic profile)
Prior to these later signs, due to flank pain, stones, or urinary tract infection (UTI) being the most common symptoms reported by patients, anyone presenting with one or more of these should be considered for diagnostic tests.
Since many symptoms are delayed until a certain degree of kidney dysfunction, screening tests should be done on persons over 18 with a family history of PKD, since it has a dominant expression in its inheritance risk. (Diagnosis in those <18 in otherwise asymptomatic young people can have adverse consequences in careers or commitment to relationships and should be delayed.)
- Ultrasound: Safe, reliable, and inexpensive, and it can tell whether the criteria for diagnosis are satisfied: at least three kidney cysts–unilateral or bilateral
Fewer cysts (1-2), insufficient for diagnosis, still indicate high risk for PKD, prompting increased surveillance and genetic testing.
In symptomatic individuals due to cysts large enough to cause the symptoms, large cysts and enlarged kidneys are easily seen on ultrasound.
- CT and MRI: Which are more sensitive and can discover many very small cysts, do not have the same criteria for diagnosis as ultrasound. Instead, >10 cysts are needed for a diagnosis of PKD
- Genetic testing: Indicated in those with uncertain ultrasound results or in screening of a related potential kidney donor
- Kidney function testing: When a person is diagnosed with PKD, the progression of renal impairment can be followed by tests such as glomerular filtration rate, urinalysis, CMP, and CBC
Simple kidney cysts are a normal age-related occurrence in the general non-PKD population, so the more accurate CT or MRI may be necessary to separate these benign age-related cysts from the pathology of PKD.