Cystic kidney disease Flashcards
If someone had a stroke, what do you ask about?
APKD
How is APKD characterised?
- characterized by epithelium-lined cavities filled with fluid or semisolid debris within the kidneys
- includes: simple cysts (present in 50% of population over 50), medullary cystic kidney, medullary sponge kidney, polycystic kidney disease (autosomal dominant and recessive) and acquired cystic kidney disease (in chronic hemodialysis patients)
Describe autosomal dominant PKD
• autosomal dominant; at least 2 genes: PKD1 (chr 16p) and PKD2 (chr 4q)
• PKD1 (1:400), PKD2 (1:1000) accounts for about 10% of cases of renal failure
• patients generally heterozygous for mutant polycystin gene but accumlate a series of second
‘somatic hits’ precipitating the condition
• PKD1 encodes a protein that is responsible for cell-cell and cell-matrix interaction and sensing
fluid flow by associating with cilia
• PKD2 encodes a protein that is a Ca2+ permeable nonselective cation channel that associates
with cilia and is thought to control intracellular Ca2+ in response to flow
What are extrareal manifestations of APKD?
most common; multiple asymptomatic hepatic cysts (33%), cerebral aneurysm (10%), diverticulosis and mitral valve prolapse (25%)
- polycystic liver disease rarely causes liver failure
- less common: cysts in pancreas, spleen, thyroid, ovary, seminal vesicles, and aorta
Ix for APKD
- radiographic diagnosis: best accomplished by renal U/S (enlarged kidneys, multiple cysts throughout renal parenchyma, increased cortical thickness, splaying of renal calyces)
- CT abdo with contrast (for equivocal cases, occasionally reveals more cystic involvement)
- gene linkage analysis for PKD1 for asymptomatic carriers
- Cr, BUN, urine R&M (to assess for hematuria)
APKD: Cx
• urinary tract and cyst infections, HTN, CRF, nephrolithiasis (5-15%), flank and chronic back pain
APKD: Rx
- goal: to preserve renal function by prevention and treatment of complications
- educate patient and family about disease, its manifestations and inheritance pattern
- genetic counselling: transmission rate 50% from affected parent
- prevention and early treatment of urinary tract and cyst infections (avoid instrumentation of GU tract)
- TMP/SMX, ciprofloxacin: able to penetrate cyst walls, achieve therapeutic levels
- adequate hydration to prevent stone formation
- avoid contact sports due to greater risk of injury to enlarged kidneys
- screen for cerebral aneurysms if family history of aneurysmal hemorrhages
- monitor blood pressure and treat hypertension with ACEI
- dialysis or transplant for ESRD (disease does not recur in transplanted kidney)
- may require nephrectomy to create room for renal transplant
What are (4) types of cystic kidney diseases?
- Simple cyst
- Polycystic kidney disease
- Medullary sponge kidney
- Von Hippel-Lindau syndrome
Describe simple renal cyst
• usually solitary or unilateral
• very common: up to 50% at age 50
• usually incidental finding on abdominal imaging
• Bosniak Classification is used to stratify for risk of malignancy based on cyst features from contrast CT
(Class I: nearly zero malignancy risk, Class IV: >90% malignancy risk)
How is the age of Px different for AR & AD PKD?
- autosomal recessive: multiple bilateral cysts, often leading to early renal failure in infants
- autosomal dominant: progressive bilateral disease leading to HTN and renal failure (40-50yo)
What is medullary sponge kidney & what does it predispose to (1)?
- cystic dilatation of the collecting ducts
* usually benign course, but patients are predisposed to stone disease
What is Von Hippel-Lindau syndrome?
- multiple bilateral cysts or clear cell carincomas (50% incidence of RCC)
- renal cysts, cerebellar, spinal and retinal hemangioblastomas, pancreatic and epididymal cysts, pheochromocytomas
