Renal 2.77-84 Flashcards
What composes the glomerular barrier?
- Fenestrated capillary endothelium
- Trilaminar glomerular basement membrane
- Foot processes of podocyte cells forming filtration slits
(Barrier is size selective and charge selective; all component are negatively charged, as are plasma proteins)
Symptoms of advanced kidney disease?
Tiredness, peripheral oedema, SOB (pulmonary oedema and anaemia), nausea, fatigue, haematuria (visible or non visible)
Features of acute glomerulonephritis?
May be oedematous, hypertensive; may have cola/smoky urine, may be oliguric/anuric, may have systemic features (rash, eye symptoms, arthralgia, haemoptysis, hair/skin changes)
Features of nephrotic syndrome?
Swelling (over days/weeks); urine frothy (massive protein leak), creatinine may be normal (hence why PCR/ACR is helpful), BP can be normal/low/high if very overloaded (oncotic pressure falls).
Nephrotic vs nephritic?
- Nephrotic is podocyte injury, changed architecture to get scarring and deposition of matrix or other elements i.e. altered permability. Leaky, with low serum albumin, high urine protein, oedema and hypercholesterolaemia. Heavy proteinuria!
- Nephritic is inflammation, with reactive cell proliferation, breaks in GBM, crescent formation. Less leaky, but may see red cell casts. e.g. small vessel vasculitis. More “AKI” like. Haematuria. Still often have proteinuria but not nephrotic range. Usually immune, rapidly deteriorating
Which diseases are more “nephrotic” than “nephritic”?
MOST: Minimal change nephropathy, FSGS, membranous nephropathy, diabetic nephropathy, amyloidosis. SLE is either
Which diseases are more “nephritic” than “nephrotic”?
MOST: anti-GBM, small vessel vasculitis, post-streptococcal glomerulonephritis, MCGN. IgA nephropathy! SLE is either
Clues in history for kidney disease?
- FHx (dialysis, transplant, ADPKD)
- Personal history (HTN, DM (if have retinopathy then will have microvascular disease everywhere), gout, CVA/PVD
- Childhood UTI (some may cause renal scarring)
- Drug history!!! (NSAIDS, antibiotics, recreational)
- Problems in pregnancy (PET)
- Previous kidney stones, cystitis, LUTS, loin pain
- Systemic signs (suggesting inflammationa)
- Swollen ankles!
- Urinary abnormalities
- Occupational (heavy metals, toxins etc.), smoking!!!!!!
Features on exam for kidney disease?
Anaemia (low epo, pulmonary haemorrhage), rash/vasculitic lesions, fevers, arthral/myalgia, eye changes, oedmea, pulses and bruits for renovascular disease, fluid status (BP l+s), palpable kidneys, transplant kidneys, palpable bladder, AAA.
Causes of hyaline casts?
Precipitated Tamm-Horsfall protein; low flow/concentrated urine/acid can cause this; so seen in dehydration/heavy exercise in normal patients.
Categorising CKD?
G1/2/3a/3b/4/5 with ACR <3, 3-30 and >30 for A1/2/3. Corresponds to risk of adverse outcomes.
ACR interpretation?
Done in diabetics. Normal range 0-3.5; microalbuminuria >2.5 (M) or >3.5 (F); proteinuria >30. (A1/2/3). Nephrotic range >220.
Total urinary protein loss interpretation?
Nephrotic is >3.5g/24 hours. Normal loss is <150mg (T-HP and albumin). Sticks only detect albumin.
Tamm-Horsfall protein and hyaline casts?
Precipitates in tubules, according to flow, pH; get casts. In immune damage/inflammation, RBC/WBC pass through damaged GBM/tubules and stick to tubular cast to give cellular casts.
Light microscopy of fresh MSU re casts etc.
Red cell casts diagnostic of glomerular disease, white cell casts of interstitial nephritis, tubular debris in acute tubular necrosis.
Investigations in renal disease?
- U+E, FBC, LFTs, BG, CRP, coag, CK, bone.
- Urinalysis + MCS + PCR
- Renal US
- ECG (K+)
- CXR (systemic/cardiac/overload)
- ABG, MSSU, virology, urate, lactate, KUB (xray), urine biochemistry
- BIOPSY
Renal screen?
Looks for intrinsic causes of disease.
- GN screen: ANCA (MPO + PR3), anti-GBM, complement, ANA/ENA/Igs, ASO/cryoglobulins/RhF
- Myeloma screen: serum (+urine) free light chains/electrophoresis
- Virology (HBV/HIV/HCV)
Imaging of kidneys?
USS + Doppler first line, AXR-KUB for calcification , stones. IVU, CT, MR, nuclear medicine (GFR, excretion, scarring), angiography (RA stenosis). Remember to be wary of contrast! + BIOPSY
What to do if someone presents with very high potassium?
ECG, repeat bloods.
Findings in membranoproliferative glomerulonephritis?
Gives mixed nephrotic/nephritic syndrome. Low C3. C3 nephritic factor usually +ve (i.e. antibody to C3 convertase).
IgA nephropathy?
Most common cause of GN. IgA deposits in glomerulus, increased by concurrent URT infection; occurs in 2-3 days rather than weeks with post-streptococcal GN. Raised serum IgA; can do IgA/G/M electrophoresis
What is pulmonary-renal syndrome?
Bleeding in lungs and GN; usually Wegener’s (GPA) or Goodpasture’s. May be SLE or microscopic polyangitis.
What is crescentic GN?
A form of rapidly progressive GN (along with focal necrotising). Glomerular tuft compressed by surrounding hypercellular (macrophages, epithelial cells) in Bowman’s space. Crescents are not diagnostic of ANCA vasculitis, but do indicate severe glomerular injury
What is rapidly progressive GN?
Syndrome of glomerular haematuria (dysmorphic red cells or red cell casts), rapidly developing kidney failure, and glomerular necrosis with or without crescent development. Causes include IgA nephropathy, ANCA, HSP, SLE, post-infectious etc.