Flashcards in Diseases of the renal system 2 Deck (41):
What is obstructive uropathy?
- Obstruction of the urinary tract
- Can occur anywhere from the renal pelvis to the urethral meatus
- Onset may be chronic or acute
- Unilateral or bilateral
What are the pelvic causes of urinary tract obstruction?
- ureteropelvic stricture
What are the ureter-intrinsic causes of urinary tract obstruction?
- sloughed papillae
What are the ureter-extrinsic causes of urinary tract obstruction?
- tumours (i.e. cervix)
- retroperitoneal fibrosis
What are the bladder causes of urinary tract obstruction?
- functional (e.g. neurogenic)
What are the prostatic causes of urinary tract obstruction?
What are the urethral causes of urinary tract obstruction?
- Posterior valve stricture
- tumours (rare)
What are the possible sequelae of urinary tract obstruction?
- Infection- cystitis, ascending pyelonephritis
- Stone/calculi formation
- Kidney damage - Acute or chronic
What do the consequences of a urinary tract obstruction depend on?
- Site of obstruction
- Degree of obstruction
- Duration of obstruction
What is the result of obstructive uropathy - acute complete obstruction?
- Reduction in glomerular filtration rate
- Mild dilatation and mild cortical atrophy
- Can cause acute renal failure
What is the result of obstructive uropathy - chronic and intermittent?
- Continued glomerular filtration -> Dilatation of pelvis+calyces
- Filtrate passes back into interstitium -> Compression of medulla -> Impaired concentrating ability
- Eventual cortical atrophy, fall in renal filtration and renal failure
What are the clinical features of obstruction?
Acute bilateral obstruction
- Acute renal failure and anuria
Chronic unilateral obstruction
- Asymptomatic initially
- If unresolved cortical atrophy and reduced renal function
Bilateral partial obstruction
- Initially polyuric with progressive renal scarring and impairment
What is the epidemiology of renal calculi?
- Affect 7-10% of the population - increasing
- Male predominance
- Peak onset 20 – 30
- Can form anywhere in the urinary tract but most commonly in the kidney
What is the pathogenesis of renal calculi?
- Either due to an excess of substances which may precipitate out e.g. Ca+
- A change in the urine constituents causing precipitation of substances e.g. change in pH
- Poor urine output – Supersaturation
- Decreased citrate levels
How are renal calculi composed?
- Calcium stones (70%) - calcium oxalate +/- calcium phosphate
- Struvite stones (15%) – magnesium ammonium phosphate
- Urate stones (5%) – uric acid
- Cystine stones (1%)
What is the most common cause of calcium stones?
Most commonly identified cause is hypercalciuria, due to:
- Bone disease, PTH excess, sarcoidosis
- Excessive absorption of intestinal Ca+
- Inability to reabsorb tubular Ca+
What are the other risk factors for calcium stones?
- Gout: forms a core for Ca+ crystal formation
-- Excess dietary intake
What is the pathogenesis of struvite stones?
1. Urease producing bacterial infection (proteus)
2. Urease converts urea to ammonia
3. Causes a rise in urine pH
4. Precipitation of magnesium ammonium phosphate salts
5. Large “staghorn” calculi
What are the causes of urate stones?
- Patients with high cell turn over e.g. leukaemia
What are the causes of cystine stones?
- Occur in the presence of an inability of kidneys to reabsorb amino acids
What investigations do you performs for renal calculi?
- Non-contrast CT scanning is gold standard-
sensitivity of >95%
- Ultrasound in pregnancy or where CT not possible 30-67% sensitive
- Intravenous urography 70% sensitive for stones
What are the sequelae of renal calculi?
- Squamous metaplasia +/- Squamous cell carcinoma
What percentage of cancers are renal cell?
What is the most common kind of renal cell carcinoma?
What is the epidemiology of renal cell carcinoma?
- Peak (65-80)
- Male > female (3:2)
What are the risk factors for renal cell carcinoma?
- Acquired cystic kidney disease (due to chronic renal failure
- Asbestos exposure
What is Von Hippel-Lindau Syndrome?
- The most common of several cancer syndromes observed in RCC
- VHL gene required for breakdown of Hypoxia Inducible Factor-1 (HIF-1) oncogene
- Therefore loss of gene function causes cell growth and increased cell survival
- Tumours develop in kidneys, blood vessels, pancreas
- VHL mutations also commonly identified in clear cell RCC
What is the presentation of Von Hippel-Lindau Syndrome?
- Hematuria, palpable abdominal mass, costovertebral pain
- systemic symptoms or metastases (25%)
What are paraneoplastic syndromes?
- Clinical syndromes caused by tumours
- Not related to the tissue that the tumour arose from
- Not related to invasion by the tumour itself or its metastases
What are the paraneoplastic syndromes associated with renal cell carcinoma?
- Cushing’s syndrome - ACTH
- Hypercalcaemia - parathyroid hormone related peptide
- Polycythaemia - EPO
What is the morphology of clear cell RCC?
- Well defined yellow tumours
- Often with haemorrhagic areas
- May extend into perinephric fat or into renal vein
What is the morphology of papillary RCC?
- More cystic
- More likely to be multiple
What is the microscopic appearance of clear cell RCC?
- Clear cell has clear cells
- Delicate vasculature
- Usually small bland nuclei
What is the microscopic appearance of papillary RCC?
- Papillary tumours
- Cuboidal, foamy cells
- Surrounding fibrovascular cores often containing foamy macrophages or calcium
What is the prognosis of renal cell carcinoma?
- Overall 5 year survival ~45%
- Organ confined > 70%
- Tumours extending into perinephric fat or renal vein ~ 50%
- Distant metastases = very poor prognosis (
What percentage of bladder tumours are urothelial cell carcinomas?
What do urothelial cell carcinomas arise from?
Arising from the specialised multilayered epithelium
Where else might urothelial cell carcinomas arise from?
Anywhere from the renal pelvis to the urethra
What are the risk factors for urothelial call carcinoma?
- Gender (male>female)
What is the presentation of urothelial call carcinoma?
- HAEMATURIA – most common
- Urinary frequency
- Pain on urination
- Urinary tract obstruction