Renal Conditions

Renal Conditions

1. Chronic Kidney Disease

   • Epidemiology
     • 1/10 adults have indication of CKD
   • Risk Factors
     • Diabetiics
     • Indigenous Australians at inc. risk
   • Aetiology
     • Glomerulonephritis
     • Diabetes
   • Pathophys
     • The underlying aetiology (cause dependent) causes a progressive destruction of nephrons
     • Proteins in blood (albumin) are lost in filtrate
       • Leads to oedema due to loss of oncotic pressure
     • Other nephrons attempt to compensate - leads to increased pressure in remaining nephrons - causing further damage
   • Stages of CKD
     • Stage 1: GFR > 90 - no symptoms
     • Stage 2: GFR 60 - 89 - still very little symptomology. Treat any cardiac related symptoms
     • Stage 3 a: GFR 45 - 59: mod. d/c in functn. May start to display some symptoms
     • Stage 3b: GFR 30 - 44: marked d/c in functn: Check for anaemia. Target BP is <135/85
     • Stage 4: GFR 15 - 29: Severely impaired functn
     • Stage 5: GFR > 15. End stage CKD: Consider dialysis or transplant if appropriate
   • End-stage Treatment
     • Haemodialysis
       • Uses the principles of ultra filtration and diffusion to remove excess electrolytes, waste products and H2O from circulation
       • Usually 3 x a week. 3 - 8 hrs each time
       • Also peritoneal dialysis
         • Dialysate is infused into the peritoneum which is used as the sem-permeable membrane for diffusion - dialysate is then removed
     • Kidney Transplant
       • Waiting list
       • Immunosuppressant (anti-rejection) drugs

2. Acute Kidney Injury

   • Pre-renal AKI
     • Aetiology
       • Caused by loss in circulating vol. or obstruction in perfusion to kidneys
     • 40 - 55 % of AKI
     • Pathophysiology
     • Manifestations
       • Oliguria/anuria
       • Increased BP due to RAAS activation
   • Intra-renal AKI
     • Acute Glomerulonephritis
       • Aetiology
         • Infections
         • Nephrotoxic drugs
         • Autoimmune disease e.g lupus
       • Manifestations
         • Inc. BP
         • Dark haematuria
         • Oedema - facial
         • Fatigue
         • N + V
       • Testing
         • Urinalysis
           • Protein, blood and WBC in blood, inc. spec grav
         • Bloods
           • Pt may be uraemic (> 8.3 mmol/L)
           • Anaemia due to v in erythropoetin prod.
       • Treatment
         • Cause of inflammation must be treated
       • Pathophys
         • Inflammation leads to inc. gaps in endothelial cells
           • Leads to loss of proteins + other blood components in urine
             • Can also lead to build up of Urea & Creatinine in the blood
       • Inflammation of the glomerulus which can lead to d/c blood flow
     • Acute Tubular Necrosis
       • Aetiology
         • Prolonged ischaemia i.e untreated pre-renal AKI or nephrotoxins
       • Pathophys
         • Nephrotoxic injury
           • Tubular cells are damaged directly or indirectly (i.e vasoconstriction)
         • Ischaemia
           • Prolonged ischaemia leads to ATP depletion & accummulation of Ca - free radicals damage cells which become necrotic & rupture
         • Injured cells release debris - combine with proteins to form CASTS
           • These + necrotic cells can occlude the lumen & inc. pressure leading to v GFR
             • Inc. pressure sees filtrate pushed back into interstium
       • Testing
         • Urinalysis typically indicative of renal tubule cells & casts
       • Treatment
   • Post-renal AKI
     • Aetiology
       • Blockage or compression leads to filtrate build up and backflow
         • Can occur b/w renal pelvis and urethral meatus
       • i.e cervical Ca or prostatomegaly
     • Rarest form - 5% of cases
     • Manifestations
       • Oliguria/anuria - Difficulty passing - pt may strain
       • Bladder distension
       • Oedema
       • HTN
       • Lower back pain
       • Severe haematuria
   • General Progression of AKI
     • 1) Initiation phase
       • Cause of AKI (e.g haemorrhage)
       • Lasts hours - days
       • Can by unsymptomatic
       • If untreated
     • 2) Maintenance Phase
       • Sig. v in GFR
       • Uraemia
       • Fluid retention - oedema
       • electrolyte imbalance
       • Impaired K levels
       • If not treated quickly at this stage
     • 3) Diuretic Phase
       • Recovery pt. 1
       • 1-2 weeks
       • Inc. diuresis due to impaired tubule wall patency during healing
         • Urea & Na are not retained
     • 4) Recovery Phase
       • GFR slowly returns to 'normal''
       • Can take up to 1 yr
     • *Not all pts follow this course*
   • Kidney Trauma
     • Signs & Manifestations
       • Oliguria
       • Haematuria
       • Flank/abdo pain
       • Localised swelling/bruising/subcut bleeding
       • Marked GFR decrease
       • PT may exhibit signs of shock
     • Due to external blunt force trauma (beating/stabbing/fall etc)

3. Kidney Function

   • Regulatory
     • Removes metabolic waste
   • Excretory
     • Reabsorption
       • Substances prev. filtered are partially reabsorbed back into circulation
     • Secretion
       • Substances are secreted from circulation into filtrate
   • Hormonal
     • R-A-A-S
       • Decrease in BP detected by baroreceptors in Juxtoglomerular apparatus
         • Renin is released
           • Renin meets Angiotensinogen (created by the liver) in the blood
             • This creates Angiotensin I
               • Angiotensin I floats around until it reaches the lungs and meets Angiotensin Converting Enzyme (ACE)
                 • ACE turns it into Angiotensin II
                   • Angiotensin II travels back to the kidney
                     • Causes a release in Aldosterone from the adrenals
                       • Aldosterone causes:
                         • Reabsorption of Na+ and H2O into circulation
                     • Angiotensin II causes:
                       • Vasoconstriction: ^ BP
                       • Pituitary releases ADH in response, inc. circ. vol
       • Collectively leads to ^ BP
     • Erythropoetin
     • Activation of Vit D
   • GFR - the amount of blood filtered through the glomerulus in 1 min.
   • Normal Lab Vals.
     • pH of urine
       • 4.5 - 8
     • Serum Urea
       • 3 - 8.3 mmol/L
     • Serum creatinine
       • 44- 133 micromol/L
     • Serum K
       • 3.3 - 5 mmol/L
     • Serum Na
       • 135 - 145 mmol/L

4. Renal Tumours

   • Primary
     • Mostly from renal cells
   • Secondary
     • Mets from lung, breast melanoma, lymphoma
   • Prolonged haemodialysis is risk factor

5. Medications

   • Diuretics
     • Loop
       • Frusemide, ethacrynic acid
     • Thiazides
       • Hydrochlorothiazide
     • Potassium Sparing
       • Spironolactone
     • Osmotic
       • Mannitol (IV)
     • Carbonic Anhydrase Inhibitor
       • Acetazalomide
       • Inhibits reabsorption of bicarbonates from renal tubules
   • Electrolytes
     • K
     • Ca
     • Na
   • Anti-diuretics

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