VIVA: Pathology - Renal and genitourinary Flashcards
What are two patterns of acute tubular necrosis with an example of each?
- Ischaemic*:
- Acute tubular necrosis due to inadequate blood flow from local or systemic causes
- Local: renal artery stenosis, microangiopathies, systemic conditions associated with thrombosis (e.g. HUS, TTP, DIC)
- Systemic: hypoperfusion from e.g. sepsis, trauma, pancreatitis - Nephrotoxic*:
- Endogenous toxins: myoglobin, haemoglobin, light chains
- Exogenous toxins: drugs (e.g. gentamicin), contrast dye, heavy metals (e.g. mercury), organic solvents (e.g. carbon tetrachloride)
- needed to pass + 1 example of each
What are the main types of renal calculi?
- Calcium oxalate and phosphate* (70%)
- Struvite or triple (magnesium ammonium phosphate; 15-20%)
- Uric acid
- Cysteine
*needed to pass + 1 other
What conditions in urine favour stone formation?
2 to pass:
- Increased concentration of stone constituents
- Changes in urinary pH
- Decreased urine volume
- Bacteria
What are the complications of ureteric calculi?
- Pain
- Haematuria
- Infection*
- Obstructive renal impairment*
- 1/2 to pass + 1 other
Define acute kidney injury
- Clinico-pathological entity
- Acute reduction of renal function* with morphologic tubular injury (usually)*
- Reversible
*needed to pass
What are the causes of AKI?
- Ischaemia / abnormal blood flow*:
- Systemic: associated with thrombosis (HUS, TTP, DIC) or hypovolaemia
- Intra-renal: angiopathies, malignant HTN - Toxic injury to glomeruli/tubules*:
- Myoglobin, haemoglobin
- Drugs
- Contrast
- Radiation - Acute tubulointerstitial nephritis:
- Hypersensitivity reaction to drugs
- IgA nephropathy
- Infections
- Metabolic diseases
- Chronic urinary tract obstruction
- Transplant reduction
- Sjogren syndrome
- Vascular disease - Obstruction (post-renal):
- Prostatic hypertrophy
- Tumour
- Clot
- Stones
*needed to pass + 1 other category, with an example from each
What is acute tubular necrosis?
- Acute renal failure with morphologic evidence of injury to tubules*
- Often necrosis of epithelial cells
- Usually reversible
*needed to pass
Describe the classic clinical course of acute tubular necrosis
2/3 to pass:
1. Initiation phase:
- Lasts 36hrs
- Transient decrease in blood flow and GFR
- Decrease in urine output, increase in urea
2. Maintenance phase:
- Sustained oliguria (urine output 40-400ml/day)
- Rising urea, hyperkalaemia, metabolic acidosis, salt and water overload
3. Recovery phase:
- Begins with increase in urine output (large volumes lost as unable to concentrate urine, may reach up to 3L/day)
- Large amount of Na+ and K+ lost in urine -> hypokalaemia
- Eventually tubular function recovers and urea and creatinine improve
- Prognosis depends on extent and duration of injury
What are the most likely causes of AKI in an elderly patient with a neck of femur fracture?
- Ischaemic injury due to hypovolaemia/hypotension as a result of femur # blood loss +/- inability to get to water
- Myoglobin deposition -> rhabdomyolysis
40F present with L loin pain and fevers. Describe the abnormalities on her urine MCS:
- Elevated WCC
- Elevated RBC
- Positive protein
- No epithelial cells
What is the most likely diagnosis?
High WCC and RBC counts* with positive protein and blood (in the absence of epithelial cells i.e. a clean catch) indicates infection*
In the clinical context consistent with pyelonephritis +/- stone
What organisms cause acute pyelonephritis?
- Gram negative bacilli (>85%), endogenous organisms
- E.g. E. coli, Proteus, Klebsiella, Enterobacter, Streptococcus faecalis (enterococcus)
- Others (e.g. Staphylococcus, fungi, viruses in immunocompromised and renal transplant patients)
What steps are involved in ascending infection of the urinary tract?
- Colonisation of distal urethra
- Entry into bladder
- Urinary tract obstruction / stasis of urine
- Vesicoureteric reflux
- Intrarenal reflux
What conditions predispose to acute pyelonephritis?
4/9 to pass:
- Urinary tract obstruction
- Instrumentation
- Vesico-ureteric reflux
- Pregnancy
- Female gender (up to 50yrs)
- Male gender (>50yrs)
- Abnormalities of the genitourinary tract (congenital or acquired)
- Diabetes mellitus
- Immunosuppression
What are the causes of urinary tract obstruction?
- Congenital:
- Urethral valves and strictures
- Bladder neck obstruction
- Ureteropelvic narrowing
- Reflux - Calculi*
- Prostatic hypertrophy*
- Tumours*:
- Prostate
- Bladder
- Cervix/uterus
- Other - Inflammation:
- Prostatitis
- Urethritis
- Ureteritis
- Retroperitoneal fibrosis - Sloughed papillae
- Clots
- Pregnancy
- Uterine prolapse
- Cystocele
- Functional:
- Neurogenic (spinal cord, diabetic) - Dysfunctional
- Ureter or bladder
- needed to pass + 1 other
What are the clinical features of acute obstruction?
In unilateral complete or partial:
- Asymptomatic
- Pain* due to distension or symptoms of underlying process (e.g. renal colic, LUTS in prostatic disease)
In bilateral partial:
- Polyuria, nocturia
- Calculi
- HTN
- Distal tubular acidosis
In bilateral complete:
- Oliguo/anuria
- Hyperkalaemia
- Increased urea and creatinine
*needed to pass
