Renal diseases 2 Flashcards
What 3 things can obstruct the renal pelvis?
1) Calculi (stones)
2) Tumours
3) Ureteropelvic stricture
What 5 things cause intrinsic obstruction of the ureter?
1) Claculi
2) Tumours
3) Sloughed papillae
4) Clots - from trauma
5) Inflammation
What 3 things cause extrinsic obstruction of the ureter?
1) Pregnancy
2) Tumours
3) Retroperitoneal fibrosis
What are the 4 types of causes of obstruction of the urinary tract?
1) Obstruction within the lumen (calculi, strictures, neoplasia)
2) Abnormalities of the wall (congenital, neoplasia)
3) External compression
4) Functional obstruction (neurological conditions, severe reflux)
What are the 3 types of strictures which can cause obstruction of the urinary tract?
1) Post-procedure
2) Post infective
3) Congenital
What is hydronephrosis?
Kidney swells due to obstruction to kidney outflow
What are the 3 key appearances of kidney in hydronephrosis?
1) dilated calyces
2) dilated pelvis
3) Cortical atrophy
What are the 2 possible outcomes of acute complete ureteric obstruction?
1) Could just get mild dilatation and mild cortical atrophy
2) Could lead to reduction in GFR which can cause acute renal failure
Through what 2 pathways does chronic and intermittent renal obstruction lead to fall in renal function?
1) Get continues glomerular filtration - dilation of pelvis and calyces - leading to eventual cortical atrophy and fall in renal filtration
2) Obstruction causes filtrate to pass back into interstitium - leading to compression of medulla - impaired concentrating ability - eventual cortical atrophy with a fall in renal filtration
What are the 2 clinical features of acute bilateral obstruction?
1) Pain
2) Acute renal failure and anuria
What are the 2 clinical features of chronic unilateral obstruction?
1) Asymptomatic initially
2) If unresolved, cortical atrophy and reduced renal function
What is the clinical feature of bilateral partial obstruction?
Initially polyuric with progressive renal scarring and impairment
In which gender and age group are renal calculi most common?
Males aged 20-30
Where do calculi most commonly form?
In the kidney but can form anywhere in the urinary tract
What are the 4 pathogenic mechanisms of renal calculi formation?
1) Due to excess of substances which may precipitate out eg. Ca2+
2) A change in the urine constituents causing precipitation of substances eg. change in pH
3) Poor urine output - supersaturation
4) Decreased citrate levels - citrate combines with calcium and prevents stone formation
What are the 4 classifications of renal stones?
1) Calcium stones - 70% - calcium oxalate +/- calcium phosphate
2) Struvite stones - 15% - magnesium ammonium phosphate
3) Urate stones - 5% - uric acid
4) Cystine stones
What are the 4 most common causes of calcium stone formation?
Hypercalcuria due to:
1) Hypercalcaemia - bone disease, PTH excess, sarcoidosis
2) Excessive absorption of intestinal Ca+
3) Inability to reabsorb tubular Ca+
4) Idiopathic
Name 2 risk factors for calcium stone formation?
1) Gout - forms a core for Ca+ crystal formation
2) Hyperoxaluria - hereditary or excess dietary intake
What are the steps in struvite stone formation?
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 2 pathogenic mechanism of urate stone formation?
1) Hyperuricaemia - gout, patients with high cell turn over eg. lerkaemia
2) Idiopathic
In what situations do cystine stones form?
Occur In presence of an inability of kidneys to reabsorb amino acids
What are the 3 investigations for renal calculi?
1) Non contrast CT scanning is gold standard - sensitivity of >95%
2) US in pregnancy or where CT is not possible - 30-67% sensitivity
3) IV urography 70% sensitive for stones
What is the gold standard imaging technique for renal calculi?
Non contrast CT scanning
Renal cell carcinoma accounts for what percentage of cancers?
3%
