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12.11.28 Renal teaching

Pyelonephritis
  • Presentation
    • High fever
    • Loin pain
    • N + V
    • Preceeding cystitis?
    • Unilateral symptoms
  • Differential for loin pain
    • AAA
    • Musculoskeletal
  • Management
    • IV Gent
      • VS Gram -ve organisms
      • 3-5 ml/kg slow IV
      • Check levels
    • IV augmentin
      • 2:1 amoxicillin and clavulanic acid 
      • Broad-spectrum (Gram +ve and -ve)

Alpha blockers
  • To treat BPH
  • Options: doxazosin, terazosinalfuzosin, tamsulosin, silodosin
  • Side-effects:
    • Relax iris dilator muscles and can cause intraoperative floppy iris syndrome (IFIS) during cataract surgery
      • Even if only taken once
    • Orthostatic hypotensionejaculation changes, nasal congestion, weakness


AKI
  • Definition
    • >50 % rise of creatinine 
  • Causes
    • Pre-renal
      • Vascular disease
    • Renal
      • Afferent arteriole
        • NSAIDs
          • Effect is much more noticable when volume depleted
      • Efferent arteriole
        • ACEi
        • ARBs
      • Toxins
        • Gentamycin (monitor very closely!)
        • Contrast (oxidising agent)
          • Protect by ADEQUATELY HYDRATING
          • NAC might also help
            • 600 mg BD, orally, 1 day before procedure
      • Rhabdomyolysis
        • Myoglobin is toxic to tubular epithelial cells
          • NB Looks life haematuria on urine dip
      • Baseline chronic kidney injury
      • Hypoxia
        • Very energy-requiring => First to go
    • Post-renal
      • Obstruction
  • AKIN classification
  Serum creatinineUrine output 
 Stage 11.5 - 2 X
or >26.4 uM 
<0.5 ml/kg/hr for >6 hr 
 Stage 22-3 X <0.5 ml/kg/hr for >12 hr 
 Stage 3>3 X <0.3 ml/kg/hr for >24 hr
or anuria for >12 hr 


Urine electrolytes
  • Pre-renal problem
    • Kidneys still working => Hold on to stuff
    • Low sodium, low FeNa, High osmolality
  • ATN
    • Kidneys broken => Let everything out
    • Sodium >20, FeNa > 2%, Osmolality <250 mOsM

Managing electrolyte abnormalities
  • Water deficit
    • Calculate based on fractional rise in sodium, assuming 60% of body weight is fluid
  • Don't correct plasma sodium by more than 8 mM per day, unless it's recently changed very quickly the other way
    • CPM => Dysarthria, Dysphagia, Falling GCS
  • Correcting serum sodium has no effect on mortality
    • It's a symptom of something underlying, which you need to fix
  • Fluid assessment
    • Best thing is POSTURAL CHANGE in pulse and BP
  • Hyponatraemia
    • Hypovolemic
      • Give saline
    • Euvolemic
      • Check cortisol
      • Check thyroid
      • Check urine osmolality
      • Only then can you diagnose SIADH 
        • Then fluid-restrict to treat
    • Hypervolemic
      • Treat the cause (heart, kidney or liver failure)

Anion gap
  • Calculation
    • Na + K - Cl - HCO3
    • Normal range 8-17 mM
  • Normal anion gap acidosis
    • Loss of HCO3 (together with counter-ion)
    • Or reduced acid excretion (renal tubular acidosis)
  • High anion gap acidosis
    • Some new acidic thing is there
    • Lactate, ketones, salicilate, methanol, etc.

Things raising urea
  • GI bleed
  • Steroids
  • Catabolic states
  • Protein
  • Tetracycline

Acute glomerulonephritis
  • Streptococcal stuff
    • IgA nephropathy happens while you're still ill (and is quite common)
    • Post-Strep GN happens 2-3 weeks later
      • It's the ANTIGEN that sticks to the basement membrane
      • Antibodies come along later and attack it
  • Goodpastures
    • Goodpasture's DISEASE = Anti-GBM antibodies 
      • Tends to occur once and never come back
    • Goodpasture's SYNDROME = Lung and Kidney involvement with an aetiology?
  • Wegener's granulomatosis is supposed to be called granulomatosis with polyangiitis 
    • As he was a Nazi
  • Investigations
    • Complement, anti-dsDNA for SLE
    • ASOT for post-Strep
    • ANCA for vasculitides
  • Classification scheme
    • Is is primary or secondary?
      • Secondary causes: Diabetes, Amyloid, SLE, RA, Myeloma
    • Irrespective of the cause, what's the clinical syndrome? (There are 5)
      • Nephrotic syndrome
      • Nephritic syndrome
      • Asymptomatic urinary abnormalities
      • Rapidly progressive glomerulonephrotis
      • Chronic kidney disease
    • What is the histopathology and pathogenesis underlying the clinical syndrome?
      • MCD, FSGS, membranous nephropathy, etc.

SLE
  • 10 times more common in female
  • 10 times more common in African Americans

HenochSchönlein purpura
  • Classic triad
    • Purpura
    • Arthritis
    • Abdominal pain
  • 40% have kidney involvement
    • Microscopic or frank haematuria

Notes
  • BPH is a HISTOLOGICAL diagnosis
  • 1/3 of TURPs are carried out because of acute retention
  • You can lose 50% of your kidney function before creatinine rises
  • Metformin => Lactic acidosis
    • Lactate uptake by the liver is diminished with metformin administration
      • Lactate is a substrate for hepatic gluconeogenesis, a process that metformin inhibits
    • Normally fine, but can build up if renal function is impaired (e.g. dehydration for surgery + ACEi)
    • Mortality of 30-50%
  • Diuretics don't help to prevent AKI
    • Can be useful in managing complications
  • Check the CK
  • londonaki.net
  • Trimethoprim is required for creatinine excretion
  • Using mannitol for TURP can => Hyperosmotic hyponatraemia
  • Trimethoprim is a mild potassium-sparing diuretic
  • Need to give lots (10-15 mg) of salbutamol to move potassium
    • And 40% of people don't respond
  • Unexplained haematuria in an elderly patient is RCC until proven otherwise
  • Source of blood in urine
    • Normal morphology => Urological cause
    • Warped/dysmorphic => Renal cause
  • Murmur in an IVDU is VALVE INFECTION 
    • i.e. Infective endocarditis
    • Can cause post-infective glomerulonephritis
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