Chapter 13: Polycystic Kidney Disease — Nephrologist-Level Evaluation and Management

Specialist chapter for nephrologists

Polycystic kidney disease is a group of inherited cystic kidney disorders rather than a single phenotype. Autosomal dominant polycystic kidney disease (ADPKD) is the dominant adult form and is caused most often by pathogenic variants in PKD1 or PKD2, although additional genes, mosaicism, de novo variants, and phenocopies complicate apparently sporadic disease. Autosomal recessive polycystic kidney disease (ARPKD) is a distinct disorder caused predominantly by PKHD1 variants and is characterized by congenital or childhood kidney disease plus congenital hepatic fibrosis and portal-hypertension risk.

The clinical task is not merely to identify renal cysts. It is to establish the correct inherited diagnosis, define prognosis, identify treatable complications, determine whether disease-modifying therapy is appropriate, counsel relatives and reproductive partners, and plan kidney replacement therapy before loss of access or severe uremic illness.

Learning objectives

By the end of this chapter, the learner should be able to distinguish ADPKD, ARPKD, acquired cystic kidney disease, and phenocopies; apply family-history and imaging-based diagnostic criteria; use eGFR trajectory, total kidney volume, Mayo Imaging Classification, genotype, PROPKD, and family history to estimate progression risk; manage hypertension, pain, cyst infection, stones, hematuria, liver-dominant disease, pregnancy, and intracranial aneurysm risk; select appropriate candidates for tolvaptan using shared decision-making; and plan dialysis, transplantation, and living-donor evaluation.

13.1 Disease spectrum and nomenclature

ADPKD is a systemic ciliopathy with progressive cyst formation in the kidneys and variable cystic disease in the liver, pancreas, seminal vesicles, and other organs. The term “hypertensive” or “cystic” kidney disease should not substitute for a genetic diagnosis when the phenotype is atypical. A patient with a few renal cysts, reduced eGFR, or a family history of “kidney failure” may have ADPKD, but may also have HNF1B-related disease, tuberous sclerosis complex, von Hippel–Lindau disease, autosomal dominant tubulointerstitial kidney disease, glomerular disease, or nonspecific age-related cysts.

The diagnosis has implications for blood relatives, pregnancy, living donation, intracranial aneurysm counseling, and access to disease-modifying treatment. A diagnosis should therefore be communicated with uncertainty when the evidence is incomplete.

13.2 ADPKD and ARPKD: clinically distinct disorders

13.3 Genetics and pathophysiology

Polycystin-1 and polycystin-2 function within primary cilia and related signaling complexes. Loss of effective polycystin signaling disrupts mechanosensation, calcium homeostasis, cyclic AMP signaling, planar-cell polarity, epithelial differentiation, and cell–matrix interactions. Cyst initiation is focal and reflects a “second-hit” model in which a germline susceptibility is followed by somatic loss of the remaining normal allele or another pathogenic event. This helps explain why cyst burden is heterogeneous even within one family.

Reduced intracellular calcium and increased cyclic AMP promote epithelial proliferation and chloride-driven fluid secretion. Abnormal extracellular matrix remodeling, inflammatory signaling, macrophage activation, mitochondrial stress, and interstitial fibrosis contribute to progressive nephron loss. Kidney enlargement may precede eGFR decline by many years; therefore, a normal eGFR does not imply low disease burden.

Genotype matters but is not destiny. PKD1 truncating variants generally confer a more severe phenotype than many nontruncating PKD1 or PKD2 variants, but within-gene variability, mosaicism, hypomorphic alleles, modifier genes, sex, blood pressure, and environmental factors influence outcome. Genetic reports should be interpreted by a laboratory or clinician experienced in inherited kidney disease.

13.4 Clinical phenotype and complications

Renal manifestations include hypertension, flank or abdominal pain, gross or microscopic hematuria, cyst hemorrhage, cyst infection, nephrolithiasis, urinary tract infection, proteinuria, progressive kidney enlargement, and CKD. Pain is not synonymous with cyst infection; a sudden severe episode may reflect hemorrhage, stone, obstruction, torsion of a cystic organ, or an unrelated intra-abdominal emergency.

Extrarenal manifestations include polycystic liver disease, intracranial aneurysm, mitral valve prolapse and aortic regurgitation, abdominal wall and inguinal hernias, diverticular disease, pancreatic and seminal-vesicle cysts, and rare vascular abnormalities. Liver cyst burden may become the dominant source of symptoms even when eGFR remains preserved.

Proteinuria is often modest. Heavy proteinuria, active urinary sediment, nephrotic syndrome, rapidly progressive eGFR loss, or an unexplained abrupt creatinine rise should prompt consideration of superimposed glomerular or interstitial disease rather than attribution to ADPKD alone.

Family history and pedigree

Obtain a three-generation pedigree that distinguishes kidney cysts from nonspecific “kidney disease.” Ask about dialysis, transplantation, sudden unexplained death, subarachnoid hemorrhage, intracranial aneurysm, liver-dominant disease, and genetic testing. A negative family history does not exclude ADPKD because of de novo disease, mosaicism, adoption, small families, early death, misdiagnosis, or incomplete family information.

Imaging

Ultrasound is useful for adults with a typical family history, but sensitivity is limited in young adults, in mild PKD2 disease, and in atypical families. In an at-risk person aged 15–39 years, the finding of at least three renal cysts in total is highly suggestive in an appropriate family context; in adults aged 40–59 years, at least two cysts in each kidney is a commonly used diagnostic threshold; and in adults aged 60 years or older, at least four cysts in each kidney supports diagnosis. These thresholds must be interpreted with imaging quality, family genotype, kidney size, and alternative diagnoses in mind.

MRI or CT is more sensitive for small cysts and allows total kidney volume assessment. MRI is preferred for repeated prognostic measurement when available because it avoids radiation. In a potential related donor, a negative ultrasound in a young person may be insufficient to exclude disease; MRI, genetic testing, or both may be needed.

Genetic testing

Genetic testing is appropriate when imaging is equivocal, the phenotype is atypical, the family history is negative or unavailable, a potential living donor is being evaluated, reproductive decisions depend on clarification, or a child may have a severe phenotype. Testing should include copy-number analysis and methods capable of detecting mosaicism when clinically indicated. Variants of uncertain significance should not be treated as diagnostic without phenotype and segregation support.

13.6 Prognosis and progression-risk assessment

Progression risk should be estimated rather than inferred from the presence of cysts alone. Key inputs include age, eGFR and its slope, height-adjusted total kidney volume, Mayo Imaging Classification, genotype, PROPKD score, early hypertension or urologic events, and the family history of kidney-failure timing.

Mayo Imaging Classification is most useful in adults with typical diffuse ADPKD morphology and adequate imaging. It is not designed for atypical morphology, isolated unilateral cystic disease, or all phenocopies. PROPKD may add information when genotype, early hypertension, early urologic events, and sex are known. A sustained eGFR decline should be confirmed using repeated measurements and interpreted alongside intercurrent illness, medication changes, and volume status.

13.7 Blood pressure and kidney-protective management

Use standardized office BP technique and supplement with home or ambulatory monitoring when readings are discordant, nocturnal hypertension is suspected, or treatment response is uncertain. In adults with ADPKD and hypertension, an ACE inhibitor or ARB is generally first-line. Avoid dual RAAS blockade. The intensity of treatment should account for age, symptoms, orthostasis, albuminuria, cardiovascular risk, and the measurement method. In young adults with preserved eGFR, intensive BP control may reduce left-ventricular-mass and kidney-volume progression when tolerated; targets should be individualized rather than copied from a single trial.

A low-sodium dietary pattern, avoidance of tobacco, appropriate weight and activity counseling, and cardiovascular-risk management are foundational. Avoid chronic NSAID exposure, especially in CKD or with RAAS blockade. Protein intake should be adequate but not excessive; very high-protein diets and unmonitored supplements may increase kidney workload.

Fluid intake and vasopressin

Higher water intake may lower vasopressin activity, but a universal prescription to force large volumes is unsafe. Consider fluid goals in relation to kidney function, serum sodium, heart failure, liver disease, occupational access to water, nocturia, and adherence. Patients should not pursue aggressive water loading if they cannot safely excrete free water or if it causes hyponatremia. The clinical evidence for hard kidney outcomes from water prescription is less established than the evidence supporting tolvaptan in selected rapid progressors.

13.8 Tolvaptan: selecting and monitoring candidates

Tolvaptan is a vasopressin V2-receptor antagonist that reduces cyclic AMP–mediated cyst growth and slows eGFR decline in appropriately selected adults. It should be considered for adults with confirmed ADPKD who are at risk for rapidly progressive disease, after shared decision-making regarding benefit, aquaretic burden, liver risk, monitoring, pregnancy, work, driving, sleep, and cost or access.

Selection should integrate Mayo Imaging Classification, eGFR slope, genotype, PROPKD, early clinical events, and family history. Age and eGFR thresholds vary across regulatory environments and should not be applied without the local product label and specialist oversight. A patient with slow progression, atypical morphology, advanced irreversible kidney failure, or a competing serious illness may have little expected benefit.

Before treatment, review liver disease, pregnancy potential, contraception, interacting drugs, baseline sodium, hydration capacity, and the patient’s ability to respond to thirst. During treatment, monitor liver tests according to the regulatory schedule, educate about polyuria and nocturia, provide a sick-day plan for vomiting, diarrhea, inability to drink, or acute illness, and reassess whether the treatment remains aligned with patient goals.

13.9 Cyst hemorrhage, pain, stones, and infection

Cyst hemorrhage commonly causes acute flank pain and hematuria and is often self-limited. Assess for obstruction, infection, anemia, anticoagulant effect, and alternative diagnoses when the presentation is severe or persistent. Avoid NSAIDs when kidney function, volume status, or bleeding risk makes them unsafe.

Cyst infection is suggested by fever, persistent focal pain, inflammatory markers, and sometimes bacteremia, but imaging findings can be nonspecific. Obtain urine and blood cultures when feasible before antibiotics. Select therapy according to likely organisms, prior cultures, renal function, drug interactions, local resistance, and tissue/cyst penetration. Fluoroquinolones or trimethoprim–sulfamethoxazole may be useful in selected cases, but neither is automatic first-line therapy. Persistent fever or relapse should prompt evaluation for an infected hepatic cyst, abscess, obstruction, resistant organism, or inadequate source control.

For nephrolithiasis, evaluate urine chemistry and stone composition where possible. Cyst burden, altered anatomy, hypocitraturia, low urine volume, and urinary stasis may contribute. Recurrent or complicated stones warrant urologic collaboration.

Chronic pain requires a multimodal plan. Identify mechanical enlargement, abdominal wall pain, hernia, infection, stones, hemorrhage, and central sensitization. Options may include acetaminophen, selected neuropathic-pain therapy, physical therapy, behavioral approaches, targeted cyst aspiration or sclerotherapy, renal denervation in exceptional cases, or nephrectomy in carefully selected patients.

13.10 Liver-dominant polycystic disease and pregnancy

Polycystic liver disease can cause early satiety, reflux, dyspnea, abdominal distension, pain, malnutrition, and impaired quality of life. Management ranges from symptom control and selected cyst procedures to somatostatin analogues, hepatic resection or fenestration, and combined liver–kidney transplantation in severe cases. Cyst infection and hemorrhage may occur in the liver as well as the kidney.

Pregnancy counseling should occur before conception. Review BP, kidney function, proteinuria, liver burden, medication teratogenicity, and obstetric risk. ACE inhibitors, ARBs, and tolvaptan should not be used during pregnancy. Hypertension and preeclampsia risk rise with CKD and baseline proteinuria. Genetic counseling should discuss the 50% transmission risk in a parent with ADPKD, variable expression, reproductive options, and the limits of prenatal prediction.

13.11 Intracranial aneurysm screening

Discuss screening rather than applying a universal rule. Screening with noncontrast time-of-flight MRA is recommended or strongly considered for people with a personal history of subarachnoid hemorrhage or intracranial aneurysm and those with a positive family history of intracranial aneurysm, subarachnoid hemorrhage, or unexplained sudden death. Shared decision-making is also reasonable before major elective surgery or transplantation, in high-risk occupations, or when patient preference remains strong after discussion of benefits, false positives, incidental findings, and follow-up burden.

New thunderclap headache, meningismus, focal neurologic deficit, seizure, or abrupt loss of consciousness requires emergency evaluation irrespective of prior screening. Detected aneurysms should be managed with cerebrovascular specialists using size, location, morphology, growth, family history, age, and procedural risk.

13.12 Kidney-failure planning, dialysis, and transplantation

Plan early when progression risk is substantial. Review vascular access, transplant referral, living-donor evaluation, nephrectomy timing, abdominal space, and the effect of massive kidneys or liver disease on dialysis modality. Peritoneal dialysis can be successful in selected patients despite cystic kidneys, but prior abdominal surgery, hernias, organomegaly, leaks, and respiratory compromise require individualized assessment.

Transplantation is the preferred kidney-replacement strategy for suitable candidates. Pre-transplant nephrectomy is not routine; it may be required for recurrent infection or bleeding, severe pain, early satiety and malnutrition, space limitation, or other complications. In living-related donation, exclude ADPKD with an age-appropriate combination of imaging and genetic assessment. A donor’s negative ultrasound should not be accepted as definitive in a young person with an at-risk genotype.

13.13 Suggested figures for the website

Figure 13.1: Diagnostic pathway. Family history and phenotype assessment should lead to ultrasound or MRI, followed by genetic testing when imaging is equivocal, family history is absent, or a donor/reproductive decision depends on certainty. A separate branch should identify phenocopies and urgent complications.

Figure 13.2: Progression-risk pathway. Show eGFR slope, height-adjusted total kidney volume/Mayo Imaging Classification, genotype, PROPKD, family history, and early hypertension/urologic events feeding into tolvaptan shared decision-making.

Figure 13.3: Extrarenal surveillance map. Show liver disease, intracranial aneurysm risk, hernias, stones, pregnancy, cardiovascular disease, and genetic counseling, with a note that screening is risk-based rather than universal for every complication.

Summary

ADPKD is a systemic inherited kidney disease in which diagnosis, prognosis, complication prevention, genetic counseling, and kidney-failure planning must proceed together. A family history and bilateral cysts support diagnosis but do not eliminate the need to consider phenocopies or superimposed kidney disease. MRI-based kidney volume, eGFR trajectory, genotype, PROPKD, and family history identify patients who may benefit from disease-modifying therapy. Tolvaptan is for selected rapid progressors, not for every person with cysts. Hypertension, liver disease, pain, infection, stones, pregnancy, intracranial aneurysm risk, and transplant planning require longitudinal specialist care.

Clinical pearls

1. Normal eGFR does not imply mild ADPKD; kidney volume may progress for years before filtration declines.
2. A negative family history does not exclude ADPKD because de novo disease, mosaicism, small families, and misclassification are common explanations.
3. Heavy proteinuria or active sediment should trigger a search for superimposed glomerular disease.
4. Use MRI/Mayo Imaging Classification and eGFR slope to discuss prognosis; do not use kidney size alone.
5. Tolvaptan requires a rapid-progression assessment, liver monitoring, pregnancy counseling, and a realistic discussion of aquaresis.
6. Do not prescribe forced high water intake without considering sodium, heart failure, advanced CKD, and free-water excretion.
7. Fever and flank pain may reflect infected renal or hepatic cyst, pyelonephritis, stone, hemorrhage, or a nonrenal process; cultures and source evaluation matter.
8. Intracranial aneurysm screening is risk-based and should be shared decision-making, not an automatic universal test.
9. A potential related donor may need MRI or genetic testing even when ultrasound is negative.
10. Massive kidneys do not automatically require nephrectomy before transplantation.

Question 1 — Equivocal ultrasound in a young potential donor

A 25-year-old woman whose father has genetically confirmed ADPKD has one 7-mm cyst in the right kidney and no cyst in the left kidney on ultrasound. Kidney function is normal. What is the best next step?

Best answer: Do not classify the ultrasound as definitively negative; obtain MRI and/or targeted genetic testing in a specialist donor-evaluation pathway.

Rationale: Ultrasound sensitivity is limited in younger adults, particularly in mild PKD2 disease and atypical families. A donor decision has a higher threshold for certainty than routine clinical diagnosis. The result should be interpreted with the father’s genotype if available.

Question 2 — Selecting a patient for tolvaptan

A 38-year-old man with confirmed ADPKD has Mayo Imaging Classification 1C, an eGFR decline of 4.5 mL/min/1.73 m² per year, and a father who required dialysis at 48. He asks about tolvaptan. What is the most appropriate approach?

Best answer: Discuss tolvaptan as a candidate for disease-modifying therapy after confirming rapid progression, reviewing liver monitoring, aquaresis, pregnancy implications for partners, interactions, and patient goals.

Rationale: Multiple independent markers support rapid progression. The treatment decision is shared and individualized; treatment is not based on cyst presence alone.

Question 3 — Fever and flank pain

A patient with ADPKD has fever, right flank pain, pyuria, and CRP elevation. CT shows a complex hepatic cyst. What should guide antibiotic selection?

Best answer: Cultures, likely organisms, renal function, local resistance, drug interactions, and tissue/cyst penetration, with reassessment for hepatic cyst infection or source-control needs.

Rationale: “Fluoroquinolone for every cyst infection” is too simplistic. Hepatic cyst infection may relapse or require specialist drainage decisions.

Question 4 — Intracranial aneurysm screening

Which patient has the strongest indication for screening discussion with brain MRA?

A patient with ADPKD and a first-degree relative who died suddenly at age 42 from a documented subarachnoid hemorrhage.

Rationale: Personal or family history of intracranial aneurysm, subarachnoid hemorrhage, or unexplained sudden death is a high-risk context for screening. Discuss false positives, follow-up, and patient preferences.

Question 5 — Pregnancy planning

A woman with ADPKD, eGFR 72, UACR 180 mg/g, and hypertension is planning pregnancy. Which medication plan is most appropriate?

Best answer: Stop ACE inhibitor/ARB and tolvaptan before pregnancy and transition to pregnancy-compatible BP therapy with obstetric-nephrology monitoring.

Rationale: RAAS blockers and tolvaptan are not used during pregnancy. Baseline CKD and albuminuria increase hypertensive and preeclampsia risk.

References

1. KDIGO. 2025 Clinical Practice Guideline for the Evaluation, Management, and Treatment of Autosomal Dominant Polycystic Kidney Disease. KDIGO guideline page.
2. Torres VE, et al. KDIGO 2025 ADPKD guideline executive summary. Kidney International. 2025;107(2):234–254. PubMed.
3. KDIGO. 2025 ADPKD Guideline PDF. [inline_viewer url="https://kdigo.org/wp-content/uploads/2025/01/KDIGO-2025-ADPKD-Guideline.pdf"].
4. Müller RU, et al. ERA/ERKNet/PKD International consensus update on tolvaptan. Nephrology Dialysis Transplantation. 2022;37(5):825–839. NDT.
5. Pei Y, et al. Unified criteria for ultrasonographic diagnosis of ADPKD. JASN. 2009;20:205–212. PubMed.
6. GeneReviews. Polycystic Kidney Disease, Autosomal Dominant. NCBI Bookshelf.

Educational notice: This chapter supports clinical learning and does not replace individualized assessment, local protocols, specialist consultation, or current product labeling.