Renal Flashcards
AKI
- acute reversible reduction in renal function
- GFR declines -> failure to maintain fluid, electrolyte, acid-base homeostasis
- reduced UO, fluid overload, rise in K, urea, creat
AKI Dx criteria
- Rise in creatinine >25umol/L in 48hrs
- Rise in creatinine >50% in 7d
- UO less than 0.5ml/kg/hr over >6hrs
stages of AKI?
1 - increase >26 mol/L within 48 hrs or 1.5 to 1.9 x reference creatinine.
Urine output <0.5 mL/kg/hr for > 6hrs
2 - increase 2 to 2.9 x reference creatinine
UO <0.5 mL/kg/ hr for > 12 hrs
3 - increase ≥3 X reference creatinine or
increase 354 μmol/L or commenced on renal replacement therapy (RRT) irrespective of stage
UO <0.3 mL/kg/ hr for > 24 hrs or anuria for 12 hrs
AKI causes ?
Pre-renal causes = Insufficient blood supply (hypoperfusion) to kidneys reduces the filtration of blood. Due to:
- Dehydration
- Shock (e.g., sepsis or acute blood loss)
- Heart failure
Renal causes are due to intrinsic disease in the kidney. Due to:
- Acute tubular necrosis
- Glomerulonephritis
- Acute interstitial nephritis
- Haemolytic uraemic syndrome
- Rhabdomyolysis
Post-renal causes = obstruction to the outflow of urine away from the kidney, causing back-pressure into the kidney and reduced kidney function = obstructive uropathy.
Obstruction may be caused by:
- Kidney stones
- Tumours (e.g., retroperitoneal, bladder or prostate)
- Strictures of the ureters or urethra
- Benign prostatic hyperplasia (benign enlarged prostate)
- Neurogenic bladder
AKI Px
- asym
- reduced UO
- pulm / peripheral oedema
- arrhythmias
- uraemia - pericarditis / encephalopathy
- sx of cause
AKI Ix
- U/E
- urine dip
- fluid balance
- renal USS
AKI Mx
- tx cause
- IV fluids
- stop worsening meds
- adjust renally-excreted meds
- tx electrolytes
- dialysis
what is Acute tubular necrosis (ATN)?
- death of renal tubular epithelial cells
- ischaemic - hypoperfusion - shock, sepsis
- nephrotoxins - eg gentamicin, radiocontrast, rhabdo (myoglobin)
how does ATN present?
- AKI
- muddy brown casts in urine
Acute interstitial nephritis (AIN) - causes Px and ix?
- Acute inflammation of renal tubule-interstitium
Cause - meds
- systemic disease, eg SLE, sarcoidosis
- infection
Px
- fever, rash, arthralgia
- eosinophilia
- mild renal impairment, HTN
Ix
- urine - sterile pyuria, white cell casts
Tubulointerstitial nephritis with uveitis (TINU)
- usually young females
Px
- fever, wt loss, painful red eyes
Ix
- urinalysis - leucocytes + protein
CKD
Chronic kidney function reduction - permanent + progressive
causes of CKD?
- diabetic nephropathy
- HTN
- Meds - NSAIDs, lithium
- glomerulonephritis
- PKD
- chronic pyelonephritis
CKD Dx criteria
> 3mo of either:
- eGFR <60
- urine albumin:creatinine ratio (ACR) >3mg/mmol
CKD classification by eGFR
1 - >90
2 - 60-89
3a - 45-59
3b - 30-44
4 - 15-29
5 - <15
CKD Px
- asym
- fatigue
- pallor
- foamy urine - proteinuria
- nausea
- anorexia
- pruritis - uraemia
- oedema
- polyuria
- HTN
- N+V
- peripheral neuropathy - vit/mineral imbalance
CKD Ix
- ECG - K
- Bloods - U/E, phosph, Ca, FBC
- urine albumin:creatinine ratio (ACR)
- urine dip + MC+S
- renal USS
- BP, HbA1c, lipids
- Kidney Failure Risk Equation
- Kidney biopsy
CKD Mx
- tx cause
- ACEi / ARB
- SGLT-2 inhibitor - dapagliflozin
- exercise, wt loss, stop smoking
- atorvastatin
- ESRF - dialysis, renal transplant
- review meds
CKD Cx
- anaemia
- CKD mineral and bone disorder (CKD-MBD)
- metabolic acidosis - oral sodium bicarb
- CV disease
- uraemia - lethargy, itch, anorexia, confusion, pericarditis
- peripheral neuropathy
- ESRF
Anaemia in CKD
- lack of EPO production -> fewer RBCs
- normocytic, normochromic
Mx
- oral / IV iron
- EPO
CKD -MBD Ix and Mx?
- high serum phosph, low vit D, low serum Ca
- kidneys secrete less phosphate, vit D not activated by kidneys (Ca not reabsorbed by kidneys, nor absorbed by gut), PTH secreted due to low Ca, increased bone turnover, osteosclerosis
Ix
- spinal XR - rugger jersey spine
Mx
- low phosph diet
- phosph binders - Ca based / can use sevelamer
- active vit D - calcitriol
- Ca in diet
- bisphosphonates for osteoporosis
Haemodialysis
- regular filtration of blood through dialysis machine
- blood access via AV fistula / tunnelled cuffed catheter
- anticoagulate with citrate / heparin
Indications for short-term dialysis
A - acidosis - severe, not responding to tx
E - electrolyte abnormalities - eg tx-resistant hyperkalaemia
I - intoxication - OD
O - oedema - severe, unresponsive pulmonary oedema
U - uraemia sx - seizures, coma
Peritoneal dialysis
- filtration in pt’s abdo - inject dialysis solution into abdo cavity, draws waste products from blood, then drain
- continuous ambulatory / automatic (at night)
Cx
- peritonitis - add vanc / teic + ceftazidime to dialysis fluid
Renal transplant
- donor kidney matched based on HLA type A,B,C
- take life-long immunosuppression
Renal transplant rejection
- Hyperacute (mins-hrs) - T2 hypersensitivity - pre-existing ABs - widespread thrombosis of graft vessels - take graft out
- Acute graft failure (<6mo) - cytotoxic T cells, reversible with steroids, immunosuppressants
- Chronic graft failure (>6mo) - AB / cell mediated