Basic Sci

Question 1

Type 1 RTA

Answer 1

DISTAL RTA - difficulty losing H+ ions (main mechanism)

MOA: problem w/ HTPase/AE1 - AI causes, drugs or structural (obstructive, sickle)

Low HCO3/K but HIGH pH (as can’t excrete H, even on acid challenge)

Question 2

Type 2 RTA

Answer 2

PROXIMAL RTA - difficulty re-absorbing HCO3

Causes - pure HCO3 transporter, or Fanconi syndrome (toxin, AI)

Fx: urine PO4, glucose, uric acid - pH variable but low/norm as can excrete H
- Bloods: HCO3, K low (causes electrolye abN, OP)

Can check w/ Bicarb challenge until serum HCO3 normal & check urine HCO3

Question 3

Type 3 RTA

Answer 3

Rare - carbonic anhydrase

Combined distal & proximal

Question 4

Pauci immune GN - Pathophys & Rx

Answer 4

Pauci immune as no IC deposited, damage/necrosis (cresenteric GN) is from neutrophils/Complement activation

LAMP present 2x ANCA

AAV is most common GN in >50yrs

Question 5

Pauci immune GN/AAV - Rx

Answer 5

Rx aggressively as high mortality

induce: GC (inc IV MP) & cyclophosphamide (PO equal to IV)
RTX: equal to CycPhos - better if relapsing (which GPA tends to)
Maintain: Steroid sparing or RTX (esp if PR3)

Question 6

Anti GBM - pathophys, Histo

Answer 6

• Sml vessel vasculitis - capillary beds (pulm-renal)
• Type 4 collagen makes up GBM
• IgG attacks α3 chain which is in the GBM (& alveolar BM)

HISTO: linear Ig staining (IgG) & C3 deposits, necrosis w/ cresenteric pattern

Question 7

Anti GBM - RF

Answer 7

• WHO? bimodal distribution - young males 20s, females 60s

RF:

• smoking
• hydrocarbons
• Alemtuzumab (CD52)
• HLADR15 (HLADR2 subtype)
• 10% have ANCA Abs (usu MPO)
• Assoc w/ Alport & membranous nephropathy (undetectable PLA2R & NS)

Question 8

Anti GBM - FX

Answer 8

RPGN (15% of all RPGN)

50% of antiGBM have pulm haemorrhage

(Pulm/renal Ddx: GPA/MPA, IGA vasc, LN, mixed cryo)
(Linear IgG in diab nephropathy but no crescents, fibrillary GN no AntiGBM Abs)

Question 9

Anti GBM - Rx

Answer 9

1. Plasmapheresis/PLEX: to rapidly remove AutoAB (daily for couple wks)
2. Steroids (Pred)
3. Cytotoxic Rx (cyclophosphamide)

Transplant possible but 2⁰ reoccurrence need to have 6months of Ø anti-GBM Abs But then recurrence is very rare (Abs are short lived) - de novo post alport Tx