Renal Flashcards
What are the key homeostatic functions of the kidney?
Regulation of BP, fluid and electrolyte balance
Acid base homeostasis
Removal of drugs and toxins
Waste elimination
At what point in an AKI are the homeostatic functions of the kidney disturbed?
Early in AKI
At what point in CKD are the homeostatic functions of the kidney disturbed?
Late in CKD
What are the endocrine functions of the kidney?
EPO synthesis Renin synthesis Gluconeogenesis Degradation of peptide hormones Hydroxylation of Vitamin D
What are the pre-renal causes of AKi?
- Hypovolamia (hypotension, haemorrhage, trauma, surgery, GI bleed)
- Sepsis (vasodilation)
- Renal artery stenosis
- Heart failure
- Drugs which affect BP eg NSAIDs
What is the most common cause of AKI?
Pre-renal: Usually hypovolaemia
Which drugs should be avoided in renal impairment?
Metronidazole Aminoglycosides (Gentamycin) NSAIDs Potassium sparing diuretics Lithium Nitrofurantoin
What are the renal causes of AKI?
- Infection/ inflammation: pyelonephritis.glomerulonephritis
- Trauma
- Ischemia
- Drug toxicity eg. Gentamicin, NSAIDs
What are the post renal causes of AKI?
- BPH
- Renal stones
- Cancer
- Fibrosis
How many stages of AKI are there?
3
What measurements are used to diagnose AKI?
Serum creatinine
Urine output
eGFR
What is Stage 1 AKI?
Serum creatinine 1.5-2 x baseline or increase in 26umol/l in 48 hours
Urine output <0.5ml/kg/hr for 6-12 hours
What is Stage 2 AKI?
Serum creatinine 2-3x baseline
Urine output <0.5 for >12 hours
What is Stage 3 AKI?
Serum creatinine >3x baseline
Urine output <0.3 for >24 hours or ANURIA
Compare the following for pre-renal vs renal AKI:
- Urine output
- Urine Na+
- Serum Na+
- Serum urea vs creatinine
PRE-RENAL:
Urine output LOW, Urine Na LOW
Serum Na HIGH, Serum Urea>Creatinine
RENAL:
Urine output initially HIGH, Urine Na HIGH
Serum Na LOW, Serum Urea=Creatinine
How should pre-renal AKI be treated in general?
FLUIDS
As renal perfusion and urine output is LOW
How should renal AKI not be treated in general?
DO NOT GIVE FLUIDS
Kidneys can’t concentrate urine, Na is lost in urine
In intrinsic causes of AKI what electrolyte disturbances are seen?
Loss of Na in urine, so Hyponatraemia
Hyperkalaemia
Leads to metabolic acidosis
How should AKI be managed?
- Determine cause (drugs? volume loss? infection?)
- Stop or avoid nephrotoxic drugs (NSAIDs, ACE/ARBS)
- Restore renal perfusion in pre-renal AKI
- Correct electrolyte disturbances
- If life threatening intrinsic AKI, may need haemofiltration or dialysis
What will the serum and urine sodium levels be in PRE-RENAL AKI?
Serum sodium HIGH
Urine sodium LOW (<15)
What will the serum and urine sodium levels be in RENAL AKI?
Serum sodium LOW
Urine sodium HIGH (>40)
What are the causes of CKD? (chronic kidney damage over >3 months, causing gradual irreversible changes in renal function)
Hypertension Atherosclerosis Diabetes Polycystic kidney disease Long term NSAID use Recurrent pyelonephritis/ glomerulonephritis
What symptoms/signs may a patient with CKD have?
Swollen ankles SOB Tiredness Nausea Haematuria Bleeding tendency
Which waste products will accumulate in the blood of CKD patients?
Urea
Creatinine
Phosphate
What tests are used to monitor CKD?
eGFR
Creatinine for end stage
Albumin:creatinine ratio to look for protein leakage
How many stages of CKD are there?
1,2,3a,3b,4,5
What is the eGFR in stage 1 CKD?
> 90
What is the eGFR in stage 2 CKD?
60-90
What is the eGFR in stage 3a CKD?
45-60
What is the eGFR in stage 3b CKD?
30-45
What is the eGFR in stage 4 CKD?
15-30
What is the eGFR in stage 5 CKD?
<15
How are serum potassium and calcium levels affected in CKD?
K+ increases leading to metabolic acidosis
Ca2+ decreases leading to secondary hyperparathyroidism
What are the biochemical changes in Stage 3-4 CKD?
Raised serum creatinine, raised albumin:creatinine ratio
Raised cholesterol and trigylceride
Decrease eGFR
Hypocalcaemia (leading to secondary hyperparathyroidism)
What are the biochemical changes in Stage 4-5 CKD?
Raised serum creatinine and urea
Raised serum phosphate
Hyperkalaemia
Which treatments do patients with stage 3b-4 CKD require?
EPO injections
Calcidiol
Phosphate binders (reduces risk of metastatic calcification)
Bicarbonate (corrects acid-bas disturbances)
Which treatments do patients with stage 5 CKD require?
Dialysis
Transplant
How would GLOMERULAR damage affect urine output in CKD?
Low urine output (oliguria)
Due to little glomerular filtrate
How would TUBULAR damage affect urine output in CKD?
High urine output (polyuria)
Due to poor reabsorption
What is renal bone disease?
- Increased bone reabsorption
- Osteitis fibrosa
- Metastatic calcification (arteries, skin)
- Oesteoporosis
What management do patients with Stage 2-3a CKD require?
Management in GP
Monitoring of eGFR, bone profile, PTH
Treat cause (HTN, diabetes)
Drugs eg. statins, antihypertensives
What are renal tubular disorders?
Defects in transporting glucose, AAs, phopshate etc.
Cause electrolyte disturbances but do NOT cause renal failure