Wk14 - Nephrology/Urology Flashcards
Definition of AKI
“Decline of renal excretory function over hours or days …recognised by the rise in serum urea and creatinine”
RIFLE/AKI criteria
What is oligouria classified as?
UO <3ml/kg/hr
What system is used in hospital labs when trying to indicate change in creatinine that signifies AKI
AKI e-Alerts
Stages of AKI (severity)
Using KDIFO:
Stage 1: Serum creatinine ≥1.5 and < 2.0 times AKI baseline or >=26.0 µmol/l increase above AKI baseline
Stage 2: Serum creatinine >=2.0 and < 3.0 times AKI baseline
Stage 3: Serum creatinine 3.0 times AKI baseline or >=354 µmol/l increase above AKI baseline
Causes of AKI
Pre Renal = Circulatory Failure “Shock”
Hypotension
Hypovolaemia (burns, diarrhoea, haemorrhage etc)
Hypoperfusion (due to HF)
Hypoxia
Sepsis (vasodilation effective peprusion dec.)
Drugs, toxins
Renal = The cells of the kidney
- Glomerulonephritis (cause by SLE), acute tubular necrosis (most common), obstructive, acute tubulo-interstitial nephritis, vasculitis, atheroembolic rhabdomyolysis, drugs - Gentamicin
Post Renal = Obstruction: Calculi Tumours (ureter, bladder, prostate, cervix, ovarian) Lymph nodes (compression Prostate Etc.
What is ATN
Acute tubular necrosis
Any pre-renal cause of AKI if severe/of sufficent duration
Usually reversible
~10-15% will never recover renal function
~A further 10-15% will have chronic renal impairment following ATN
Causes of ATN
ATN is always due to under perfusion of the tubules and/or direct toxicity: Hypotension Sepsis Toxins Or often, all three
Examples of toxins causing ATN
Exogenous:
Drugs (eg, NSAID’s gentamicin, ACEi)
Contrast
Poisons (eg, metals, antifreeze)
Endogenous: Myoglobin Haemoglobin Immunoglobins Calcium Urate
Management of AKI
Acute or chronic?
Bloods – both urea and creatinine ↑
Potassium
Urine output (usually <400ml/day)
Clinical assessment of fluid status (BP, JVP, oedema, heart sounds)
Underlying diagnosis (history, exam, meds)
Treatment:
Immediate
Airway and Breathing
Circulation – shock - restore renal perfusion
–> hyperkalaemia
–> pulmonary oedema
Remove causes - drugs, sepsis
Exclude obstruction (with ultrasound) & consider ‘renal’ causes
are the pre-renal causes sufficient to account for ARF?
Ask for help: ICU or renal unit
Diagnostic process for AKI - investigations
AKI or CKD?
History and exam (e.g. septic, rashes, haemoptysis, rhabomyolysis etc)
Drugs (prescribed, OTC, supplements, radio-contrast and abuse)
Urinalysis
Renal ultrasound
‘GN’ screen – ANCA, ANA, Immunoglobulins + EP, complement, aGBM, Urine Bence Jones protein
Others blood film, LDH, CK etc
Renal ultrasound to exclude obstruction:
Also gives info on size (CKD - small kidneys)
Loss of cortico-medullary differentiation suggests CKD
Treatment of hyperkalaemia (with AKI) - causing arrhythmias (e.g. tachycardia)
Reduce absorption from gut – Calcium Resonium 15g 4x day orally (or enema)
Insulin 10-15units actrapid+ 50ml 50% dextrose moves potassium into cells (watch Blood Glucose)
Calcium gluconate 10ml 10% as cardiac membrane stabiliser
Absolute and relative indications for dialysis
Absolute:
Refractory potassium ≥6.5 mmol/l
Refractory pulmonary oedema
Relative:
Acidosis (pH <7.1)
Uraemia (esp if urea >40) - pericarditis, encephalopathy
Toxins (lithium, ethylene glycol etc)
Definition of CKD
CKD = kidney damage of GFR<60ml/min per 1.73m2 for 3 months or more
How serum creatinine can be used to measure kidney function
Serum creatinine product of muscle metabolism.
Fairly constant production and constant serum levels
24h urine creatinine clearance – often inaccurate
Freely filtered but tubular secretion
Serum Creatinine is inversely proportional to GFR and also depends on muscle mass
Effect of muscle mass leas to:
Overestimation of function in women
Overestimation of function in the elderly
Overestimation in other low muscle mass groups e.g. amputees, para/quadriplegics, rheumatoid arthritis
Problems with eGFR
Only validated in whites and African-Americans
Mean age 50 ie not validated in elderly
Values above 60ml/min not distinguishable so reported as eGFR >59ml/min
Drug dosing – doesn’t take weight into account
AKI – not valid
Pregnancy
Classification of CKD
According to eGFR
Stage 1 - >90 2 - 60-89 3a - 45-59 3b - 30-44 4 - 15-29 5 - <15
Proteinuria
Proteinuria suggests the filtration barrier has been damaged
Some protein in urine normal : <150mg/day
About 2/3 is albumin
Dipstick for albumin. Not very accurate
1+ : can see in fever, exercise, normals
24h collection gold standard but not used now in routine practice
PCR and ACR useful and correlate with 24h
Measures conc of urine (proteinuria) ‘against creatinine (to be able to compare it against a constant value)
ACR and PCR (mg/mmol)
Normal ACR <2.5
Normal PCR <20
Albuminuria : ACR >30
ACR is about 2/3 of equivalent PCR result eg ACR 70 = PCR 100 = 24h urine protein 1g
Nephrotic range proteinuria : PCR >300 (3g/24h)
If heavy albuminuria use PCR to follow progress
Aetiology of CKD
1) Diabetic nephropathy
2) Renovascular disease/ischaemic nephropathy (Look for asymmetric kidneys on scan)
3) Chronic glomerulonephritis
4) Reflux nephropathy/chronic pyelonephritis
5) ADPKD
6) Obstructive uropathy
Symptoms of advanced CKD
Pruritus Nausea, anorexia, weight loss Fatigue Leg swelling Breathlessness Nocturia Joint/bone pain Confusion
Signs of advanced CKD
Peripheral and pulmonary oedema Pericardial rub Rash/excoriation Hypertension Tachypnoea Cachexia Pallor &/or lemon yellow tinge
CKD g
Targeted screening for CKD
Interventions to slow the rate of progression of CKD and reduce cardiovascular risk
Medicines to replace impaired individual functions of the kidney
Advanced planning for future renal replacement therapy (RRT)
Renal replacement therapy
Slowing progression of CKD
Aggressive BP control Good diabetic control Diet Smoking cessation Lowering cholesterol Treat acidosis
ACEi/ARB in CKD
Reduction in eGFR of up to 25% in first few weeks is a good thing
Will get more of a reduction if critical reduced renal perfusion (volume depletion, sepsis, RAS)-
sick day rules
Anaemia in CKD
Common, particularly when eGFR <30
Iron absorption & utilisation suboptimal
Replace iron, B12, folate first if low
ESA eg Darbepoietin alfa 30microg every 2 weeks
Trigger usually Hb <100g/l
Target Hb 100-120g/l.
Higher associated with adverse CV events
How are the kidneys associated with CKD
Secondary hyperparathyroidism:
CKD-MBD Treatment
Activated vitamin D : Alfacalcidol : start 0.25mcg
Occasionally Mg supplements
Phosphate binders : target phosphate 0.9-1.5 mmol/l
- Calcium based : calcium carbonate/acetate
- Non-calcium : sevelamer, lanthanum, aluminium
Calcimimetic : cinacalcet
Parathyroidectomy
Indications for dialysis
Medically resistant hyperkalaemia Medically resistant pulmonary oedema Medically resistant acidosis Uraemic pericarditis Uraemic encephalopathy
& specific drug overdoses
Signs of clinically uraemic patient
Anorexia Vomiting Itch Restless legs Weight loss Metabolic taste
What level of GFR signifies you to start dialysis
Not a specific number
Generally eGFR between 5-10ml/min/1.73m2
(When GFR in single digits)
Assessed on an individual patient basis
What are the options for renal replacement
Haemodialysis - hospital or home
Peritoneal dialysis - predominantly home based, 2 variations - CAPD, APD
Renal transplant - 2 types - cadaveric or living transplant
2 aims of haemodialysis
Haemodialysis access
Removal of solutes – e.g. potassium, urea: DIFFUSION
Removal of fluid ‘ultrafiltration’ - pressure: HYDROSTATIC FILTRATION
Haemodialysis access:
TCVC (tunneled central venous catheter)
AV fistula
Graft
Practicalities of HD
Hospital or home based – hospital much more common
Standard: 4h, 3 times a week
Multiple other options – mainly home based:
- 6h 3 times a week
- Short daily dialysis
- Daily overnight
Home based treatment gives greater flexibility and empowerment but need carer, space and capital investment
Haemodialysis complications
‘Crash’ (acute hypotension) Access problems (with fistula) Cramps Fatigue Hypokalaemia Blood loss Dialysis disequilibrium Air embolism
Describe the 2 types of peritoneal dialysis
Continuous cycling peritoneal dialysis is done with a machine at night on a daily basis.
Continuous ambulatory peritoneal dialysis is done on a daily basis. Patients manually exchange the peritoneal fluid
Practicalities of PD
Home based therapy
Better with some residual renal function
Different glucose concentrations of dialysate to provide more or less ultrafiltration
Dialysate contains other electrolytes like in HD
Gradual treatment – no good for AKI
Simple procedure once taught
Maintain independence
PD complications
Infection - peritonitis
Glucose load – development or worsening control of diabetes
Mechanical – hernia, diaphragmatic leak, dislodged catheter
Peritoneal membrane failure
Hypoalbuminaemia
Encapsulating peritoneal sclerosis
Some patients not suitable: Grossly obese Intra-abdominal adhesions Frail Home not suitable
Conservative care for kidneys
Increasingly frail and elderly population
Recognition that survival may be slightly better on RRT but quality may not
Symptom based management
Modality choice consideration for renal replacement
Lifestyle Frailty Vascular access Time – travel to and from hospital Carer Physical – concurrent medical problems e.g. disseminated malignancy, severe dementia, severe psychiatric disease
Problems not helped by dialysis
Anaemia – need erythropoesis supplementing agents and iron
Renal bone disease – need phosphate binders and vitamin D
Neuropathy
Endocrine disturbances
Transplantation practicalities
Immunosuppressive medication for transplant patients
Cadaveric waiting list - Kidney after brainstem death - Kidney after cardiac death Average wait on the list 3 years Not all patients suitable for transplant
Immunosuppresion:
Cyclosporin (tacrolimus)
MPA
Pros and cons of transplantation of kidney
Pros No dialysis Better level of renal function Can live much more independently Better life expectancy Fertility better
Cons Immunosuppressive medication for duration of transplant Increased cardiovascular risk Increased infection Post transplant diabetes Skin malignancies and others
Lower urinary tract infection
Upper
Lower - Cystitis
Upper - Pyelonephritis, renal abscess
Urosepsis
Urosepsis, complicated UTI: Temp >38ºC HR>90/min RR>20/min WBC >15.0 or <4.0
Those more affected with bacteriruia and RxF
Preschool age, girls > boys
Adults
Non- pregnant females,1-3%
Males, 0.1%
Other at risk groups: Hospitalised Catheterised Diabetics Anatomical abnormalities Pregnant patients
Ascending UTI
Urethral colonisation
female>male
Multiplication in bladder
Ureteric involvement
Descending UTI
Blood-born infections
Involvement of renal parenchyma
Clinical features of UTI
Suprapubic discomfort Dysuria Urgency Frequency Cloudy, blood stained, smelly urine Low-grade fever Sepsis
Failure to thrive, jaundice; in neonates
Abdominal pain and vomiting in children
Nocturia, incontinence, confusion in the elderly
Common organisms causing UTI
Gram negative bacilli E.coli Klebsiella sp. Proteus sp. Pesudomonas sp.,...
Gram positive bacteria Streptococcus sp. - Enterococcus sp. - S. agalactiae (Group B streptococcus) Staphylococcus sp. (S.saprophyticus, S.aureus (S.aureus usually with presence of a catheter )),…
Anaerobes (uncommon)
(Candida sp.)
Investigation of UTI
Non-pregnant women: 1st presentation, culture not mandatory Dipstick, high false positive rate Check previous culture results Antibiotic 3-7/7 No response to treatment Urine culture Change antibiotic Children and men Send urine for each and every presentation Treat appropriately
UTI in pregnancy - Tx
Common
Send urine sample with each presentation
Treat for 7-10 days
- Amoxicillin and cefalexin relatively safe
- Avoid Trimethoprim in 1st trimester
- Avoid Nitrofurantoin near term
May need hospital admission for IVs if severe
Can develop into pyelonephritis (~30%) - causes risk of bacteraemia and sepsis
Classification of recurrent UTI & Tx
≥2 episodes in six months ≥3 episodes/year (Microbiological confirmed) Mostly women Send sample with each episode Encourage hydration Encourage urge initiated and post coital voiding Intravaginal/oral oestrogen Urology investigation
Self administered single dose/short course therapy Single dose post coital abx Prophylactic antibiotics If simple measures fail Ideally six months Trimethoprim Nitrofurantoin (Can cause pulmonary fibrosis) Associated risk with long term use Development of antimicrobial resistance
Catheter associated UTI - a complicated UTI
Millions of catheter insertions/year Colonisation common - Treatment not required Infection (HAI, 35%) - Disturbance of the flushing system - Colonisation of the urinary catheter - Biofilm production by bacteria
Likely organisms
Patient’s flora
Healthcare environment
Complications of catheters
CAUTI Obstruction-hydronephrosis Chronic renal inflammation Urinary tract stones Long term risk of bladder cancer
Prevention of catheter infections
Catheterise only if necessary Remove when no longer needed “ “Forgotten catheter” Remove/replace if causing infection Catheter care (bundles) Hand hygiene
Tx of CAUTI
Check recent /previous microbiology Start empirical antibiotics Remove catheter if not needed Replace catheter under antibiotic cover Historically Gentamicin/ Ciprofloxacin Poor Gram positive cover Increase in resistant GNB- treatment failure May need to use broad spectrum antibiotics
Features of acute pyelonephritis
Upper urinary tract infection Moderate to severe infection Ascending infection involving pelvis of kidney Enlarged kidney Abscesses on surface of kidney
Management of acute pyelonephritis
Check previous/recent microbiology results (might be on wrong antibiotics)
Send urine +/- blood culture+/- imaging
Community: Co-amoxiclav/ Ciprofloxacin/ /Trimethoprim (NICE guideline)
Options may be limited
Allergy
Drug interaction
Antimicrobial resistance
Uncomplicated pyelonephritis, 7-14/7 antibiotic
Complicated pyelonephritis, ≥ 14/7 therapy
+/- radiological/surgical intervention
Even under right antibiotic likely to be pyrexial
What is a complication of pyelonephritis
Renal abscess
Perinephrtic abscess
Renal abscess
Complication of pyelonephritis Similar symptoms to pyelonephritis Usually positive urine and blood culture Gram negative bacilli, likely organisms Can become life-threatening - Emphysematous pyelonephritis - Urgent urology review - High mortality rate Poor response to antibiotics
Perinephric abscess
Complication of pyelonephritis
Uncommon Risk factors - Untreated LUTI, anatomical abnormalities - Renal calculi - Bacteraemia, haematogenous spread
Common organisms:
Gram negative bacilli, E.coli, Proteus sp.
Gram positive cocci, S.aureus, Streptococci
Candida sp.
Symptoms - Similar to pyelonephritis - Localised signs/symptoms Usually positive blood cultures Pyuria +/- bacterial growth Treat empirically as complicated UTI Poor response to antibiotic therapy Surgical management
Management of complicated UTIs
FBC, U+Es, CRP
Urine sample
Urethral, CSU, Suprapubic, Nephrostomy
Blood culture if pyrexia or hypothermic
Renal ultrasound
CT KUB
Antibiotic therapy14/7 or more
PO Amoxicillin, Trimethoprim, Nitrofurantoin
Pivmecillinam, Fosfomycin
(Co-amoxiclav, Ciprofloxacin, Cefalexin)
- Look out for penicillin allergyReasons for pyuria with no bacteria
Previous/recent antibiotic Tumour Calculi Urethritis (check for Chlamydia) Tuberculosis
Features of acute bacterial prostatitis - likely organisms
Male UTI Localised infection Usually spontaneous May follow urethral instrumentation Fever, perineal/ back pain, UTI, urinary retention Diffuse oedema, micro abscesses
Likely organisms:
Gram negative bacilli, e.g. E.coli, Proteus sp.
S.aureus (MSSA, MRSA)
N.gonorrhoea (less common)
Investigations for acute bacterial prostatitis
Urine culture, usually positive Blood culture Trans-rectal U/S CT/ MRI Obtaining prostatic secretions NOT advisable
Complications of acute bacterial prostatitis & Abx management
Complications: Prostatic abscess Spontaneous rupture Urethra, rectum Epididymitis Pyelonephritis Systemic sepsis
Antibiotic management:
Check recent/previous microbiology
Ciprofloxacin/ Ofloxacin (no streptococcus cover)
D/W microbiology in systemic infections
Features of chronic prostatitis
Rarely associated with acute prostatitis May follow Chlamydia urethritis Recurrent UTIs Diagnosis difficult Relapse common Most asymptomatic
Symptoms:
Perineal discomfort/ back pain
+/- low grade fever
UTI symptoms
Common organisms:
Gram negative bacilli, e.g. E.coli, Proteus sp.
Enterococcus sp.
S.aureus (MSAA, MRSA)
Features of epididymitis
Inflammatory reaction of the epididymis
Relatively common
Aetiology:
Ascending infection from urethra
Urtheral instrumentation
Symptoms:
Pain, fever, swelling, penile discharge
Symptoms of UTI/urethritis
Common organisms causing epididymitis
GNB (e.g. enterobacteriaece), enterococci, staphylococci
TB in high risk areas and individuals
In sexually active men - rule out Chlamydia and N.gonorrhoea (urethritis)
Features of orchitis
Inflammation of one or both testicles Testicular pain and swelling Dysuria FEver Penile discharge
Aetiology:
Usually mumps
Bacterial - complication of epidiymitis
Bacterial orchitis:
Acutely unwell
Rule out sexually transmitted bacteria
Intravenous antibiotics - as per complicated UTI
