Cystic Diseases of the Kidney: Polycystic Kidney Disease (PKD)

Introduction

Polycystic Kidney Disease (PKD) is a genetic disorder characterized by the formation of numerous cysts in the kidneys. These cysts can lead to impaired kidney function, hypertension, and eventual kidney failure.

Types of PKD

Autosomal Dominant Polycystic Kidney Disease (ADPKD)

ADPKD is the most common form of PKD and occurs in adulthood. It is caused by mutations in the PKD1 or PKD2 genes, leading to cyst formation and progressive kidney enlargement.

Autosomal Recessive Polycystic Kidney Disease (ARPKD)

ARPKD is a rarer but more severe form that manifests in infancy or childhood. Mutations in the PKHD1 gene cause cystic dilation of the kidney tubules, often leading to early-onset renal failure and hepatic fibrosis.

Pathophysiology

PKD cysts arise due to abnormal cell proliferation and fluid secretion, disrupting normal kidney architecture. In ADPKD, cysts progressively enlarge, causing compression of kidney tissue and impaired filtration.

Clinical Features

Hypertension
Hematuria
Flank pain
Progressive renal dysfunction
Associated liver cysts (in ADPKD)

Diagnosis

Diagnosis is primarily through imaging studies:

Ultrasound: detects kidney enlargement and cysts
CT/MRI: provides detailed visualization of cyst burden
Genetic testing: identifies mutations in PKD1, PKD2, or PKHD1 genes

Management

Treatment focuses on symptom control and slowing disease progression:

Blood pressure control (ACE inhibitors, ARBs)
Pain management
Dialysis or transplantation in advanced cases
Newer therapies targeting cyst growth (e.g., tolvaptan)

Conclusion

Polycystic Kidney Disease is a serious genetic condition with varying severity. Early diagnosis and management can help mitigate complications and improve patient outcomes.