Adult Polycystic Kidney Disease

Physical Examination

General examination:

• Pallor (anaemia) or polycythaemia

• Hands: Leukonychia (chronic kidney disease), asterixis (uremia)

• Mouth: Uremic fetor (breath smelling like ammonia)

Inspection:

• Abdominal distension (due to enlarged kidneys or liver)

• Visible abdominal mass (rarely)

Palpation:

• Bilateral, smooth, non-tender, ballotable renal masses

• Hepatomegaly (due to polycystic liver disease)

Percussion:

• Shifting dullness (if ascites is present, a rare complication)

Auscultation:

• Normal bowel sounds

Additional examination:

• Blood pressure measurement (hypertension is common in ADPKD patients)

• Examination of other systems (e.g., central nervous system for intracranial aneurysms, cardiovascular system for aortic or mitral valve abnormalities)

Investigations

Laboratory:

• Complete blood count (anaemia or polycythaemia, leukocytosis)

• Renal function tests (elevated creatinine, urea)

• Electrolytes (hyperkalemia, hyponatremia)

• Urinalysis (hematuria, proteinuria)

• Liver function tests (if liver involvement is suspected)

Imaging:

• Abdominal ultrasound (confirm diagnosis, assess kidney size, number of cysts, presence of liver cysts)

• MRI or CT scan (assess for complications, such as cyst haemorrhage or infection, more accurate assessment of renal and liver cysts)

• Renal scintigraphy (assess differential renal function if needed)

Invasive:

• Kidney biopsy (rarely needed if atypical presentation or to exclude other causes of renal disease)

Other tests:

• Genetic testing (confirm the diagnosis in uncertain cases, especially for at-risk family members)

• Echocardiogram (evaluate for associated cardiac abnormalities)

• Screening for intracranial aneurysms (if family history or high risk)

Management

General management:

• Multidisciplinary approach: nephrologist, urologist, radiologist, transplant surgeon, and genetic counselor working together for optimal patient care

• Regular monitoring of kidney function: serum creatinine, eGFR, electrolytes

• Blood pressure control: ACE inhibitors or ARBs as first-line agents

• Lifestyle modifications: low salt diet, regular exercise, smoking cessation, maintaining a healthy weight

• Patient education: information about the disease, potential complications, and importance of regular follow-up

Medical management:

• Pain management: analgesics for cyst-related pain, avoid NSAIDs due to potential kidney injury

• Infection treatment: antibiotics for urinary tract infections or cyst infections, guided by culture and sensitivity

• Tolvaptan: vasopressin receptor antagonist to slow the growth of cysts and decline of renal function (only in select cases, monitor for liver toxicity)

• Erythropoiesis-stimulating agents: for anaemia secondary to chronic kidney disease

• Hyperkalemia management: dietary modification, potassium binders, loop diuretics if needed

• Acidosis management: oral bicarbonate supplementation if necessary

• Hyperphosphatemia management: dietary phosphate restriction, phosphate binders

• Secondary hyperparathyroidism management: vitamin D analogues or calcimimetics

Surgical management:

• Cyst drainage: for large, symptomatic cysts causing pain or pressure

• Nephrectomy: for massively enlarged kidneys causing significant symptoms prior to kidney transplantation

• Dialysis: hemodialysis or peritoneal dialysis when approaching end-stage renal disease (ESRD)

• Kidney transplantation: for eligible patients with ESRD, offers improved quality of life and survival

Other management:

• Genetic counseling: for patients and families to understand inheritance pattern and implications for offspring

• Screening for extrarenal manifestations: liver cysts, intracranial aneurysms, cardiac valve abnormalities

Causes of the palpable kidney(s)

Unilateral renal enlargement:

• Renal cyst: simple, hemorrhagic, or infected

• Hydronephrosis: due to obstruction (e.g., stone, tumor, ureteropelvic junction obstruction)

• Renal abscess: bacterial infection leading to a localized collection of pus

• Renal hematoma: secondary to trauma or spontaneous in patients on anticoagulation

• Renal neoplasm: benign (e.g., angiomyolipoma) or malignant (e.g., renal cell carcinoma)

• Compensatory hypertrophy: secondary to contralateral renal disease or nephrectomy

Bilateral renal enlargement:

• Polycystic kidney disease

• Amyloidosis: deposition of amyloid proteins in the renal parenchyma

• Bilateral hydronephrosis: due to obstruction (e.g., bladder outlet obstruction, neurogenic bladder, or bilateral ureteral obstruction)

• Bilateral renal neoplasms: synchronous bilateral renal cell carcinoma or lymphoma

• Infiltrative renal diseases: sarcoidosis or tuberculosis involving both kidneys

Extra-renal manifestations of PKD

• Liver cysts: most common extrarenal manifestation, often asymptomatic but can cause pain, hepatomegaly, or portal hypertension if severe

• Pancreatic cysts: typically asymptomatic and detected incidentally on imaging

• Spleen cysts: usually asymptomatic, rarely cause complications

• Intracranial aneurysms: 5-10% prevalence, higher risk in those with a family history of intracranial aneurysms or subarachnoid hemorrhage, screening recommended in high-risk patients

• Arachnoid cysts: benign cerebrospinal fluid-filled cysts, usually asymptomatic

• Cardiac valve abnormalities: mitral valve prolapse, aortic regurgitation, or tricuspid regurgitation

• Diverticular disease: especially colonic diverticulosis, more common in ADPKD patients

• Hernias: higher prevalence of inguinal and umbilical hernias in ADPKD patients

• Seminal vesicle cysts: may cause infertility in male patients

Abdominal pain in PKD

• Cyst hemorrhage: bleeding into a cyst can cause sudden, severe pain, often localized to the flank or abdomen

• Cyst infection: an infected cyst can present with abdominal pain, fever, and tenderness over the affected kidney

• Cyst rupture: rupture of a cyst into the renal pelvis or perinephric space can cause pain and, in some cases, hematuria

• Kidney stone: patients with polycystic kidney disease have an increased risk of developing kidney stones, which can cause colicky abdominal or flank pain, hematuria, and urinary symptoms

• Hydronephrosis: obstruction of the urinary tract by cysts or stones can lead to renal pelvis dilation and pain

• Mass effect: enlarged kidneys due to multiple cysts can cause abdominal discomfort, early satiety, or a sensation of fullness

• Liver cysts: enlargement or complications of liver cysts (e.g., hemorrhage, infection, rupture) can cause upper abdominal pain

• Extrarenal manifestations: complications of ADPKD-related colonic diverticulosis (e.g., diverticulitis) or hernias may cause abdominal pain

Causes of Nephrectomy in PKD

• Mass effect: massively enlarged kidneys causing significant abdominal pain, discomfort, early satiety, or respiratory compromise due to compression of adjacent organs

• Intractable pain: severe, persistent pain unresponsive to conservative management, such as analgesics or cyst drainage

• Recurrent or persistent infection: repeated episodes of cyst infection or pyelonephritis, despite appropriate antibiotic therapy

• Uncontrolled hypertension: refractory high blood pressure secondary to renal compression and activation of the renin-angiotensin system, unresponsive to medical management

• Hematuria: persistent or recurrent gross hematuria secondary to cyst rupture or other renal complications, unresponsive to conservative measures

• Suspected malignancy: when imaging or clinical features raise concern for renal cell carcinoma, which can be challenging to differentiate from complex cysts in polycystic kidney disease

• Preparation for kidney transplantation: in patients with end-stage renal disease (ESRD) due to polycystic kidney disease, nephrectomy may be performed to create space for the transplanted kidney