Nephrology AS cards Flashcards
Renal Physiology - Na Reabsorption
- Main factor determining extracellular volume
- Decreased BP and decreased NaCl @ macula densa –> increased renin release –> aldosterone release –> more Na, less K (insertion of pumps).
Renal Physiology - Water Reabsorption
- Determines ECF osmolality
- Increased osmolality or decreased BP –> ADH release
What is absorbed at the PCT?
Reabsorption of filtrate
- 70% of total Na+ reabsorption
- reabsorption of amino acids, glucose, cations.
- Bicarbonate reabsorbed using carbonic anhydrase
What is absorbed at the thick ascending limb?
Creates osmolality gradient
- 20% of Na reabsorption
- Na/K/2Cl triple symporter
What is absorbed at the distal convoluted tubule?
pH control and Ca reabsorption
- 5% of Na reabsorption
- Apical NaCl co-transporter
- Ca2+ reabsorption under control of PTH
What is absorbed at the medullary collecting duct?
pH and K regulation
- Na reabsorption coupled to K or H excretion
- Basolateral aldosterone-sensitive Na/K pump.
What is absorbed at the cortical collecting duct?
Regulation of water reabsorption
- Water reabsorbed by aquaporin-2 channels.
Endocrine function of the kidney?
- Secretion of renin by juxtaglomerular apparatus
- EPO synthesis
- 1a-hydroxylation of vitamin D (controlled by PTH).
What are the classes of diuretics?
- Carbonic Anhydrase Inhibitors
- Loop Diuretics
- Thiazide diuretics
- K-Sparing diuretics
- Osmotic Diuretics
MOA and example of Carbonic Anhydrase Inhibitors (acetazolamide)
MOA: inhibit carbonic anhydrase in PCT
Effect: decreased HCo3 reabsorption –> small increase in Na loss.
Used in glaucoma
SE: drowsiness, renal stones, metabolic acidosis
Acetazolamide
MOA and example of Loop diuretic?
Examples: furosemide, bumetanide
- MOA: inhibits Na/K/2CL symporter in thick ascending limb
- Effect: massive NaCl excretion, Ca and K excretion.
- Use: Management of oedema - CCF, nephrotic syndrome and hypercalcaemia
- SE: hypokalaemic metabolic alkalosis, ototoxic, hypovolaemia, hypocalcaemia, renal impairment from dehydration + toxic effect, gout
MOA and examples of thiazide diuretics?
Bendroflumethazide, indapamide
- MOA: Inhibits NaCl co-transporter in Distal Convoluted Tubule
- Effects: moderate NaCl excretion, increased Ca reabsorption
- Use: HTN, decreased renal stones, mild oedema
- SE: decreased K, hyperglycaemia, increased urate (CI in gout). Can cause hypercalcaemia, hypokalaemia, hyponatraemia.
What are the K-sparing diuretics?
Spironolactone and amiloride
What is the MOA of K-sparing diuretics?
Spiro: Aldosterone antagonist
Amiloride: blocks DCT/CD luminal Na channels
Eplerenon - K-sparing diuretic.
Effect: Increased Na excretion, decreased K and H excretion
What are K-sparing diuretics used for?
Used with loop or thiazide diuretics to control K loss.
Spiro has long-term benefits in aldosteronism (LH, HF)
Use spironolactone in ascites.
Ascites = Fluid leaves the intravascular space = Decreased blood pressure = activates RAAS and increased aldosterone resulting in further fluid retention which worsens ascites. SO give aldosterone antagonist stops the RAAS overactivation
SE: increased K, anti-androgenic (gynaecomastia)
What are osmotic diuretics? Give examples?
Mannitol
MOA: freely filtered and poorly reabsorbed
Effect: decreased brain volume and decreased ICP
USe: glaucoma, increased ICP, rhabdomyolysis
SE: decreased Na, Pulmonary oedema, n/v.
Causes of haematuria - renal?
Transient or spurious non-visible haematuria
- UTI
- Menstruation
- Vigorous exercise
- Sexual intercourse.
Renal:
- Congenital: PCK
- Trauma
- Infection: pyelonephritis
- Neoplasm
- Immune: GN, TIN
Extra-renal
- Trauma: stones, catheter
- Infection: Cystitis, prostatitis, urethritis
- Neoplasm: bladder, prostate
- Bleeding diathesis
- Drugs: NSAIDs, frusemide, cipro, cephalosporins
Painless, frank haematuria. Warrants an urgent referral on the cancer pathway due to his age.
Gold standard = bladder cancer diagnosis = Cystoscopy.
What can give you a false positive for haematuria?
Myoglobin, porphyria
Proteinuria 1+ meaning?
30mg/dL
Proteinuria 2+ meaning?
300mg/dl
What is proteinuria defined as?
Urine protein: creatinine ratio <30 mg/mmol.
PCR <20mg/mM is normal. >300 = nephrotic.
Commonest causes of proteinuria?
- DM
- Minimal change
- Membranous
- Amyloidosis
- SLE
Other causes of proteinuria?
HTN ATN TIN UTI Fever, orthostatic
False positive for proteinuria?
Bence-Jones protein
Definition of microalbuminuria?
30-300mg/24hr
Earliest detectable sign of deterioration in DM
Other causes:
- HTN
- minimal change GN
What are the 3 types of casts?
RBC, WBC or Tubular.
RBC: glomerular haematuria
WBC: Interstitial nephritis or pyelonephritis
Tubular: ATN
Differential from urine if glomerular in nature?
- Haematuria, proteinuria, red cells/casts.
Differential from urine if tubular in nature?
White cell casts, small protein, leucocyturia
Differential from urine if pre-renal in nature?
Nothing
What is creatinine?
- Synthesised during muscle turnover
- Freely filtered and small proportion secreted by PCT
- Increased muscle –> Increased creatinine: age, sex, race
- Plasma Cr doesn’t increase above normal until 50% increased in GFR
What is urea?
- Produced from ammonia by liver in ornithine cycle
- Increased with protein meal (upper GI bleed or supplements)
- Decreased with hepatic impairment
- 10-70% is reabsorbed: depends on urine flow
- Decreased flow –> increased urea reabsorption (in dehydration)
How do you interpret isolated increased urea?
Decreased flow = Hypoperfusion/dehydration
How do you interpret increased urea and increased creatinine?
Decreased filtration (renal failure)
What is creatinine clearance?
- Vol of blood that can be cleared of a substance in 1min
- CrC roughly approximates GFR as it is freely filtered and only a small proportion secreted (~10%)
- Required urine concentration from 24hr collection
- Can use radiolabelled EDTA: very rarely done.
What is eGFR
- Modification of Diet in Renal Disease (MDRD) equation
- CAGE = serum creatinine, age, gender, ethnicity!
- Obvious need for urine collection.
What are the problems with eGFR?
- Validated for patients with established renal failure: ?applicable to general population
- Most elderly people are in >stage 3 CFR by eGFR: may npt progress or impinge on their health.
- eGFR is too pessimistic in mild renal impairment.
- Factors which may affect the result
= pregnancy, muscle mass, eating red meat 12 hrs prior to sample being taken.
Higher creatinine in body builder = artificially lower eGFR.
What are the causes of Renal Disease? - Pre-renal
Pre-renal
- Shock
- Renal vascular: RAS,
- Toxins: NSAIDs, ACEi
- Thrombosis
- Hepatorenal syn
What are the causes of Renal Disease? - Renal
Glomerulonephritis
Acute Tubular Necrosis
Interstitial disease
What are the causes of Renal Disease? -Post-renal
Disease of renal papillae, pelvis, ureters, bladder or urethra. SNIPPIN - Stone - Neoplasm - INflammation: stricture - Prostatic hypertrophy - Posterior urethral valves - Infection: TB, schisto - Neuro: post-op, neuropathy
What are the presentations of renal failure?
- Uraemia
- Protein loss and Na+ retention
- Acidosis
- Hyperkalaemia
- Anaemia
- Vitamin D deficiency
Symptoms of uraemia?
Pruritis N/V Anorexia Lethargy Confusion restless legs Metallic taste Paraesthesia: neuropathy Bleeding Chest pain: serositis
Signs of uraemia?
Pale skin, Striae Pericardial/Pleural rub Fits Coma
Symptoms of protein loss and Na+ retention.
Symptoms
- Polyuria, polydipsia
- Oliguria, anuria
- Breathlessness
Signs of protein loss and Na+ retention.
- Oedema
- INcreased JVP
- HTN (or decreased BP)
Symptoms of acidosis?
Breathlessness
Confusion
Signs of acidosis?
Kussmaul respiration?
Symptoms of hyperkalaemia?
Palpitations
Chest pain
Weakness
Signs of hyperkalaemia - ECG?
Peaked T waves Flattened P waves Increased PR interval Widened QRS Sine-wave pattern --> VF
Symptoms of anaemia?
Breathlessness Lethargy Faintness Tinnitus Aortic flow murmur
Signs of anaemia?
Pallor
Tachycardia
Flow murmurs (ESM @ apex)
Vitamin D deficiency symptoms?
Bone pain
Fractures
Signs of vitamin D Deficiency?
Osteomalacia
- Looser’s zones (pseudo #)
- Cupped metaphyses
What is bacteriuria?
Bacteria in urine, symptomatic or asymptomatic
What is a UTI?
Symptomatic with +ve culture or dipstick
What is Urethral syndrome
Symptomatic but no bacteriuria
What is the classification of UTIs?
- Uncomplicated: Normal GU tract + functioning.
- Complicated: abnormal GU tract, outflow obstruction, decreased renal function, impaired host defence
- Recurrent: further infection with new organism
- Relapse: further infection with same organism
Types of Presentation of UTI?
Pyelonephritis
Cystitis
Prostatitis
Presentation of pyelonephritis?
- Fevers, rigors
- Loin pain and tenderness
- Vomiting
- Oliguria if ARF
Presentation of cystitis?
- Frequency and urgency
- Polyuria
- Haematuria
- Dysuria
- Suprapubic tenderness
- Foul smelling urine
Presentation of Prostatitis?
- Flu-like symptoms*
- Low backache
- Dysuria
- Tender swollen prostate on PR
Sterile Pyuria - what can cause it?
Presence of leukocytes without infection
- TB
- Treated UTI
- Appendicitis
- Calculi
- Tubulointerstitial nephritis
- Papillary necrosis
- Polycystic Kidney
- Chemical cystitis (cyclophosphamide)
Risk factors for UTI?
Female Sex Pregnancy Menopause DM Abnormal tract: stone, obstruction, catheter
Organisms for UTI?
- E.coli
- Staphylococc Saprophyticus
- Proteus (Struvite renal stones)
- Klebsiella
Investigations for UTI?
- Dipstick
- MSU for MCS
- Bloods: FBC, U+E, Blood cultures (if systemic signs)
- US: Children, men, recurrence, pyelonephritis
Positive cultures of a UTI?
- 10^4 cfu/ml for most
- Women with symptomatic UTI >10^2 cfu/l
- Men >10^3 cfu/ml (if 80% of growth due to a single organism)
Management of UTI? Cystitis
General: drink plenty of water
Cystitis
- Management for 3-6 days
- Trimethoprim 200mg BD
- Nitrofurantoin 50mg QDS (not in RF) - Causes lung fibrosis.
- Cefalexin 500mg BD (good in RF)
- Co-amoxiclav 625mg TDS
Management of UTI? Pyelonephritis?
Cefotaxime/Ceftriaxone 1g IV BD for 10days
No response: Augmentin 1.2g TDS + gentamicin.
Gentamicin can cause an intrinsic AKI.
UTI prevention?
Drink more
Abx prophylaxis
? Cranberry juice
Features of Glomerulonephritis?
- group of disorders resulting from glomerular damage
- Can –> Proteinuria ± haematuria
- Can –> AKI or ESRF
Presentations of glomerulonephritis?
Asymptomatic haematuria
Nephrotic syndrome
Nephritic syndrome
Those glomerulonephritidies that cause nephrotic syndrome?
Most common cause = Diabetes.
- Deposition disease - Amyloidosis
- Minimal change disease (child with nephrotic syndrome)
- Focal and segmental glomerulosclerosis (may be idiopathic or secondary to HIV)
- Membranous nephropathy (presentation: proteinuria/nephrotic syndrome/chronic kidney disease)
- Membranoproliferative GN (generally mixed picture)
Those that mainly cause Nephritic syndrome?
- Postinfectious GN
- IgA nephropathy/ young adult with haematuria following URTI
- Rapidly progressive GN (rapid onset, often presenting as acute kidney injury).
Causes include Goodpasture’s ANCA positive vasculitis. - Vasculitis (Wegener’s + nose bleeds).
- Anti-glomerular basement membrane (GBM)
Investigations for Glomerulonephritis?
Urinanalysis
- Haematuria, proteinuria, dysmorphic RBC, leukocytes, RBC casts. Bence-Jones proteins.
Bloods
- Basic: FBC (anaemia) , U+E (elevted creatinine, liver enzymes for Hep B/C), ESR (ESR elevated)
- Complement (C3 and C4) for immune complex GN
- Abs: ANA, dsDNA, ANCA (pauci immune or anti-glomerular basement membrane) , GBM (GBM)
- Serum protein electrophoresis and Ig
- Infection: ASOT (post-strep) HBC, and HCV
Imaging
- CXR: infiltrates (Goodpasture’s, Wegener’s)
- Renal US ± Biopsy
General management for glomerulonephritis?
Refer to nephrologist
Rx HTN aggressively (<130/80)
Include ACEi/ARA.
Asymptomatic Haematuria causes?
- IgA nephropathy
- Thin BM
- Alports
What is the commonest GN in the developing world?
IgA nephropathy/Berger’s Disease
What are the features of IgA nephropathy?
- Young male with episodic macroscopic haematuria occuring a FEW DAYS after URTI
- Rapid recovery between attacks.
- increased IgA
- Can occassionally lead to nephritic syndrome.
What do you find on biopsy for IgA nephropathy?
IgA Deposition in mesangium
Treatment for IgA nephropathy?
If low risk of progression - supportive.
If HTN or proteinuria develops - all patients should receive ACEi and ARBS.
- Steroids or cyclophosphamide if decreasing renal function (6 months)
- Prognosis = 20% ESRF after 20yrs.
What is Thin BM disease?
- AD disease, commonest cause of asymptomatic haematuria
-Features
Persistent, asymptomatic microscopic haematuria.
V. small risk of ESRF.
What is Alport’s syndrome?
X-linked inheritance
- Haematuria, proteinuria = progressive renal failure NOT APKD
- Sensorineural deafness
- Lens dislocation + Cataracts (lenticonus)
- Retinal flecks
- Females: haematuria only.
Alport’s patient with a failing renal transplant - caused by presence of anti-GBM anitbodies leading to Goodpasture’s syndrome like picture.
Can’t see - Lenticonus
Can’t pee - CKD, hematuria
Can’t hear a high C - sensorineural deafness
What is nephritic syndrome/Acute Glomerulonephritis?
- Haematuria (macro/micro) + red cell casts
- Proteinuria –> Oedema (especially periorbital)
- HTN
- Oliguria and progressive renal impairment
Causes of nephritic syndrome?
- Proliferative/post strep
- Crescentic/Rapidly Progressive Glomerulonephritis.
What are the features of proliferative/post-strep GN?
- Young child develops malaise and nephritic syndrome with smoky urine
- 1-2 WEEKS AFTER sore throat or skin infection.
- Delayed antibody-mediated syndrome. Pyelonephritis and a UTI would present differently including symptoms such as fever, dysuria and pain.
- Present with headache, malaise, haematuria, proteinuria, HTN, Low C3, raised ASO
Investigations for proliferative/post-strep glomerulonephritis?
Increase ASOT
Decreased C3
Biopsy shows: IgG and C3 deposition.
Management of post-strep/proliferative GN?
- Supportive management
- Consider antibiotics
- ACEi to treat proteinuira >1g/day
Minority develop RPGN
What is crescentic/RPGN?
Most aggressive GN which can lead to ESRF in a few days.
What are the types of RPGN?
Type 1: Anti-GBM - (Goodpasture’s) - 5% Presents with haemoptysis and haematuria Rare condition associated with pulmonary ahemorrhage and RPGlomerulonephritis.
Factors increasing likelihood of pulmonary haemorrhage.
- Smoking, LRTI, Pulmonary oedema, inhalation of hydrocarbons.
Manage = plasma exchange, steroids, cyclophosphamide.
Type 2: Immune Complex deposition (complication of any immune complex deposition = Berger’s, post-strep, endocarditis, SLE)
Type 3: Pauci Immune - 50%
- cANCA: Wegener’s (Granulomatosis with Polyangiitis)
- pANCA: microscopic polyangiitis, Churg-Strauss
- Even if ANCA+ve, may still be idiopathic: no features of systemic vasculitis
Investigations and management of RPGN?
- Manage with Corticosteroids and other immunosuppressants.
- Manage CVS factors - lifestyle measures, statins, BP control.
What is the definition of nephrotic syndrome?
- Proteinuria (>3.5g/24hr)
- Hypoalbuminaemia (<30g/L)
- Peripheral oedema (periorbital, genital, ascites, peripheral).
- Hyperlipidaemia
- Lipiduria
Often intravascularly depleted with decreased JVP (CCF).
What are the investigations for nephrotic syndrome?
Same as glomerulonephritis
- Basic bloods: FBC, U+E, ESR
- Complement (C3 and C4)
- Abs: ANA, dsDNA, ANCA, GBM
- Serum protein electrophoresis and Ig
- Infection: ASOT, HBC, HCV.
All adults get biopsy.
Steroids 1st with children: mostly minimal change.
Complications of nephrotic syndrome?
- Hyperlipidaemia: increased cholesterol and triglycerides
- Infection: decreased Ig, decreased complement activity
- VTE: up to 40%. - Therefore prophylactic LMWH required. Due to loss of anti-thrombin III, protein C&S, rise in fibrinogen
- Loss of thyroxine-binding globulin = low total, but not free, thyroxin level
HIT.
Nephrotic syndrome secondary to systemic disease?
DM: glomerulosclerosis
SLE: Membranous - Present with proteinuria on urinalysis. Pre-eclampsia cannot occur before 20 weeks therefore cannot be possible. Can cause deranged TFTs due to urinary loss of thyroid-binding globulins, leading to a low total T4 level.
Amyloidosis
Causes of nephrotic syndrome?
- Minimal change glomerulonephritis (common cause in children) - can be due to NSAIDs, Hodgkin’s lymphoma, EBV.
Offer prednisolone and only if poor prognosis then give biopsy.
- Membranous Nephropathy (most common cause of adults - due to malignancy, but also diabetic nephropathy)
- Focal Segmental GS
- Membranoproliferative/ Mesangiocapillary GN/ Berger’s/ IgA nephropathy.
Summary of minimal change glomerulonephritis?
- Commonest cause of nephrotic syndrome in children
Causes:
- URTI - infectious mononucleosis
- drugs - NSAIDs, rifampicin
- Hodgkin’s lymphoma, thymoma
- Biopsy: normal light micro, fusion of podocytes on EM
- Management: Steroids (cyclophosphamide if steroid unresponsive)
- Prog: 1% –> ESRF.
1/3 of patients have infrequent relapses and 1/3 of patients have frequent relapsed (2/3) with recurrent episodes.
Summary of membranous nephropathy?
20-30% of adult nephrotic syndrome - Associations: Mainly malignancy Ca: lung, colon, breast Autoimmune: SLE, thyroiditis, rheumatoid Infections: HBV, malaria, syphilis Drugs: Penicillamine, gold, NSAIDs
On biopsy: Subepithelial immune complex deposits, basement membrane thickening on light microscopy. Subepithelial spikes on silver stain. Positive immunohistochemistry for PLA2
Management:
- All patients should receive an ACEi or an ARB.
- immunosuppression if renal functions declines. E.g steroid + cyclophospamide.
Prognosis: 40% spontaneous remission.
Summary of focal segmental glomerulonephritis?
If adult with nephrotic syndrome think focal segmental.
- Commoner in Afro-Caribbeans
- Common nephrotic syndrome in adults
- Idiopathic or Secondary: VUR, Berger’s, SCD, HIV.
- Biopsy: focal scarring, IgM deposition
- Management: Steroids or cyclophosphamide/cyclosporin
- Prognosis: 30-50% –> ESRF (may recur in transplants).
Summary of membranoproliferative GN?
- Rare
- May lead to nephrotic or nephritic syndrome
- Associated with HBV, HCV, Endocarditis
- Prognosis: 50% –> ESRF
What is the general management of nephrotic syndrome?
- Monitor U+E, BP, fluid balance, weight
- Treat underlying cause:
Majority are steroid-responsive. - Symptomatic/complication management:
Oedema: Salt and fluid restrict + furosemide
-
Proteinuria: ACEi/ARA decreased proteinuria
Increased lipids: Statin - VTE: Tinzaparin (risk of clotting)
Management HTN.
What is the definition of AKI?
Significant decline in renal function over hrs or days manifesting as an abrupt and sustained increased in serum urea and creatinine and/or a fall in urine output.
What are the causes of AKI?
Pre-renal
Renal
Post-renal
Causes of pre-renal AKI
- Shock (hypovolaemia, haemorrhage, sepsis, 3rd space filling)
- renovascular compromise (NSAIDs, ACEi, bilateral renal artery stenosis + ACEi.
In pre-renal urea:creatinine ratio indicated a pre-renal cause.
Normally in pre-renal kidneys will try to hold onto sodium and there will be low fractional sodium excretion.
Causes of Renal AKI?
ATN:
Ischaemia: shock, HTN, HUS, TTP
Direct nephrotoxin: drug hypertensitivity
Causes of post-renal AKI?
SNIPPIN
- Stone
- Neoplasm
- Inflammation: Stricture
- Prostatic hypertrophy
- Posterior urethral valves
- Infection: TB, Schisto
- Neuro: Post-op, neuropathy
How does AKI present?
- Uraemia
- Acidosis
- Hyerkalaemia
- Fluid overload
Oedema, including pulmonary
Increased BP (or decreased)
S3 gallop
Increased JVP
Clinical assessment of AKI? How do you decide if acute or chronic?
Can’t tell for sure?: Manage as acute.
Features of chronic AKI?
- Hx of comorbidity: DM, HTN
- Long duration of symptoms
- Previously abnormal bloods (GP records)
Volume depletion assessment in AKI?
- Postural hypotension
- Decreased JVP
- increased pulse
- Poor skin turgor, dry mucous membranes
How to assess for GU tract obstruction in AKI?
Suprapubic discomfort Palpable bladder Enlarged prostate Catheter Complete anuria (rare in ARF)
What are the rare causes of AKI?
Associated with proteinuria±haematuria
Vasculitis: rash, arthralgia, nosebleed.
What are the investigations for AKI?
Bloods: FBC (anaemia, leucocytosis), U+E, (creatinine, potassium, urea), urea to creatinine ratio, LFTs, Glucose, Clotting, Ca, ESR
ABG: hypoxaemia (oedema), acidosis, increased K+
GN screen: if cause unclear
Urine dip: Dip, MCS, chemistry (U+E, PCR, Osmolality, BJP)
ECG: Hyperkalaemia
CXR: pulmonary oedema
Renal US: renal size, hydronephrosis** - must be done within 24h of assessment if no identifiable cause/ at risk of urinary tract obstruction
NB: in pre-renal failure, urine is concentrated and Na is reabsorbed –> increased osmolality, Na <20mM.
What is the classification of AKI?
RIFLE Classification
- 3 grades of AKI and 2 outcomes
- Classification determined by worst criteria
RIFLE Classification - Those at risk of AKI?
Risk:
- Increased Cr x 1.5
- Decreased GFR >25%
- UO: <0.5ml/kg/h x 6hr
In the 1s
RIFLE Classification - Those with acute kidney injury?
Injury:
- Increased Cr x 2
- Decreased GFR >50%
- UO: <0.5ml/kg/h x 12hrs
In the 2s
RIFLE Classificaiton - Those with acute kidney failure?
Failure:
- Increased Cr x 3
- Decreased GFR >75%
- UO: <0.3ml/kg/h x 24hr, or anuria x 12hr.
In the 3s
RIFLE classification - acute kidney loss?
- Persistent ARF = complete LOF > 1month
RIFLE classification - End stage kidney disease
- LOF >3 months.