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NP36 Nephrology
Cystic Diseases of the Kidney Toronto Notes 2019
• mostcommonextrarenalmanifestations:multipleasymptomatichepaticcysts(33%),mitralvalve prolapse (25%), cerebral aneurysm (10%), diverticulosis
• polycysticliverdiseaserarelycausesliverfailure
• lesscommonextrarenalmanifestations:cystsinpancreas,spleen,thyroid,ovary,seminalvesicles,and
aorta
Signs and Symptoms
• oftenasymptomatic;discoveredincidentallyonimagingorbyscreeningthosewithFHx • acuteabdominalflankpain/dulllumbarbackpain
• hematuria(frequentlyinitialsignismicroscopichematuria,otherwisegrosshematuria) • nocturia(urinaryconcentratingdefect)
• extra-renal presentation (e.g. ruptured berry aneurysm, diverticulitis, mitral valve prolapse, aortic regurgitation tricuspid valve prolapse)
• HTN(increasedreninduetofocalcompressionofintrarenalarteriesbycysts)(60-75%) • ±palpablekidneys
Common Complications
• urinarytractandcystinfections,HTN,chronicrenalfailure,nephrolithiasis(5-15%),flankandchronic back pain
Clinical Course
• polycysticchangesarealwaysbilateralandcanpresentatanyage
• clinicalmanifestationsrarebeforeage20-25
• kidneysarenormalatbirthbutmayenlargeto10xnormalsize
• variableprogressiontorenalfunctionalimpairment(ESRDinupto50%byage60)
Investigations
• radiographicdiagnosis:bestaccomplishedbyrenalU/S(enlargedkidneys,multiplecyststhroughout renal parenchyma, increased cortical thickness, splaying of renal calyces)
• CTabdowithcontrast(forequivocalcases,occasionallyrevealsmorecysticinvolvement) • gene linkage analysis for PKD1 for asymptomatic carriers
• Cr,BUN,urineR&M(toassessforhematuria)
Treatment
• goal:topreserverenalfunctionbypreventionandtreatmentofcomplications
• tolvaptan has been used to slow decline of renal function, however its use has been limited by side
effects
• educatepatientandfamilyaboutdisease,itsmanifestations,andinheritancepattern
• geneticcounselling:transmissionrate50%fromaffectedparent
• preventionandearlytreatmentofurinarytractandcystinfections(avoidinstrumentationofGUtract)
• TMP/SMX,ciprofloxacin:abletopenetratecystwalls,achievetherapeuticlevels
• adequatehydrationtopreventstoneformation
• avoidcontactsportsduetogreaterriskofinjurytoenlargedkidneys
• screenforcerebralaneurysmsiffamilyhistoryofaneurysmalhemorrhages
• monitorbloodpressureandtreatHTNwithACEI
• dialysisortransplantforESRD(diseasedoesnotrecurintransplantedkidney)
• mayrequirenephrectomyforsymptomaticreliefofpainorduetorecurrentinfections
Autosomal Recessive Polycystic Kidney Disease
• 1:20,000incidence
• prenataldiagnosisbyenlargedkidneys(duetocysticdilatationofthecollectingducts);ifsignificantin
utero can result in Potter sequence.
• perinataldeathfromrespiratoryfailure
• associatedwithhepaticfibrosis
• patientswhosurviveperinatalperioddevelopCHF,HTN,CKD,portalhypertension
• treatedwithdialysis,kidneyand/orlivertransplant
Medullary Sponge Kidney
• common,autosomaldominant,usuallydiagnosedin4th-5thdecades
• multiplecysticdilatationsinthecollectingductsofthemedulla
• renalstones,hematuria,andrecurrentUTIsarecommonfeatures
• anestimated10%ofpatientswhopresentwithrenalstoneshavemedullaryspongekidney
• nephrocalcinosisonabdominalx-rayin50%patients,oftendetectasymptomaticpatientsincidentally
• diagnosis:contrastfilledmedullarycystsonIVPleadingtocharacteristicradialpattern(“bouquetof
flowers”), “Swiss cheese” appearance on histological cross-section
• treatUTIsandstoneformationasindicated
• doesnotresultinrenalfailure
Extra-Renal Manifestations of PCKD
• Hepatic cysts
• Mitral valve prolapse • Cerebral aneurysms • Diverticulosis
Tolvaptan in Later-Stage Autosomal Dominant Polycystic Kidney Disease
NEJM 2017;377:1930-42.
Objectives: To evaluate the efficacy and safety of the vasopressin V2-receptor antagonist tolvaptan in patients with later-stage autosomal dominant polycystic kidney disease.
Methods: Phase III, randomized withdrawal, multicenter, placebo-controlled, double-blind trial. Results: Change in estimated GFR from baseline was -2.34 ml/min/1.732 in the tolvaptan group (95% CI, -2.81 to -1.87) vs. -3.61 ml/min/1.732 in the placebo group (95% CI, -4.08 to -3.14). Conclusions: Tolvaptan resulted in a slower
decline than placebo in the estimated GFR over a 1 yr period.