Spectrum of renal diseases Flashcards
What are the clinical manifestations of nephropathies?
Failure to thrive abdominal mass hematuria asymptomatic proteinuria hypertension anemia polyuria oligoanura polydipsia oedema acidosis respiratory distress enuresis uti (CAKUT is a risk factor for UTI) renal osteodystrophy renal failure electrolyte abnormalities Vomiting, Diarrhea
Causes of Glomerulonephritis
Causes of idiopathic nephrotic syndrome (MCD, MPGN, MGN, FSGS) and secondary nephrotic syndrome (Hep B, HIV, Hep C, Syphilis, Heavy metals - Gold, Mercury, Obesity)
Congenital (within 3months of life) and Infantile (3m to 1 year) Nephrotic syndrome
Causes of Nephritic syndrome - PIGN, igA nephropathy
Systemic vasculitides with secondary renal involvement - SLE, Henoch Schonlein purpura vasculitis, Anti-neutrophilic cytoplasmic autoantibody vasculitis
Congenital glomerulonephritis - Alport’s
Causes of Cakut
Agenesis - Dysplasia - Hypoplasia
Cystic Kidney disease
Obstructive Uropathies - PUJ (commonest), VUJ, PUV
Other causes of non-obstructive urinary tract dilatation - Prune Belly
Reflux nephropathies - VUR, UTI’s
Neurogenic bladder
Where are the kidneys located
They are retroperitoneal, between the costovertebral angle.
Describe the functional structure of the kidney
Tubules in Interstitium
Glomerulus - Filtration of fluids, solutes and waste
Interstitial cells are mesangial cells - Tissue macrophages in Kidney.
There’s deposit of complement and immunoglobulin in interstitium - stain under immunoflourescence.
Efferent arteriole is narrower than afferent.
Anatomy of the Nephron - Tubules and blood supply
Tubules are more susceptible to ischemia and hypoxia, so ATN more common than Cortical necrosis.
Tubules can regenerate.
Peritubular capillaries aid tubules to transform substances and secrete some.
What are the functions of the kidney?
*Homepstasis
Water and electrolyte balance
Nitrogenous waste disposal (urea, cr, Uric acid)
Acid base balance
*Hormogenesis
Erythropoietin from the interstitium
Ca2+ & PO42- metabolism via Vit D3 activation (1 hydroxylation - in 1,25 hydroxycholeciferol) - Renal Rickets
What are the consequences of a failed Kidney?
Failed homeostatic function
*Accumulation of metabolic waste - raised BUN, SCr: Uraemia (feeling unwell &lack of energy)
- Failed excretion of daily H+ load - acidosis
- K+ build up - HyperK+
- Retention of PO42- & Mg2+ and reciprocal fall of Ca2+ (solubility product - PO4 2.2+ Ca =5)
- Poor urine output - Fluid retention - Oedema
- Abnormal urine chemistry (protein and blood) and sediments (sloughed tubular epithelium, RBC cast)
Consequences of a chronically injured Kidney (>3months)
Fibrosis - then loss of critical nephron mass - glomerulus and tubules is shed (broad waxy casts - nephron).
Small shrunken kidney.
Impaired synthetic function- decreased erythropoietin production (normochromic anemia)
Decreased production of 1a hydroxyl add - 1,25 vit D3 deficiency - renal osteodystrophy
What are the traditional marker for Kidney Injury
Serum Creatinine - endogenous, metabolic product of the muscles, excreted by the Kidney.
Urine output determination
Urine dipstick for proteinuria and blood
What is the issue with SCr as a marker of Kidney injury
Creatinine levels rise after ~50% of renal function is lost (time lag before it rises
Levels depends on muscle bulk
What are the newer bio markers for Kidney injury? (Early rise)
Neutrophil Gelatinase Associated Lipocalin [Blood and Urine]
AKIM -1 (urine)
Cystatin C (blood)
IL-18
Who is at risk of acute Kidney Injury?
Critically ill patient requiring ICU care
Hypovolemic patient - Diarrhoea and Vomiting +/- dehydration, Shock, Burns, Septicemia, Nephrotic Syndrome.
Glomerulonephritis
Severe sepsis/Severe malaria
Receiving nephrotoxics including radiographic contrast
Hypoxia - Asphyxia, Pneumonia, Cyanosed, Severe asthma, Status epilepticus/prolonged convulsion
Hemoglobinuria/Myoglobinuria (crushed injury)
Abnormal urinalysis - proteinuria/hematuria, WBC’s/nitrite
Other causes of Kidney injury in Children
Chronic malformation of the kidney structure/adjoining urinary tract - CAKUT
Spectrum of Kidney Diseases (1)
Inflammatory conditions of the Kidney (Nephritis)
Glomerulo-Nephritis- Nephrotic or nephrotic
Tubulointerstitial Nephritis including pyelonephritis
CAKUT including cystic kidney diseases
Other hereditary nephropathies - cong nephrotic, cong nephritis (Alport), cong TIN (nephronophthisis)
Spectrum of Kidney Diseases - may lead to failure
Tubulopathies (eg. cystinosis- Fanconi syndrome, Barters
Metabolic (eg. oxalosis)
Ischemic or toxic injury
Malignancies ( Wilma tumor, leukemia, leukemia
Causes of TIN
Drug-induced - antibiotics, analgesics, anti-oxide drugs
Hereditary TIN - nephronophthisis
Diagnosis is made when eosinophils infiltrating the kidney, peripheral eosinophilia(red staining white cells) on biopsy.
Eosinophils in urine.
The three classical features of Prune Belly Syndrome
Wrinkled abdomen (absent abdominal wall)
Cryptorchidism
Hydroureters (with or without Hydronephrosis)
What are the Pre-renal causes of AKI
Volume loss - Real (loss through vomiting, diarrhea, hemorrhage )or apparent ( septicemia - blood vessels dilate)
What are the intrinsic and post renal causes of AKI?
Unresolved pre-renal ARF - uncorrected diarrhea, shock (acute tubular necrosis) Hypoxia conditions Toxins and poisons Drugs Glomerulonephritis Tubulointerstitial nephritis
Post-renal events - any cause of obstructive uropathy
What are the causes of Chronic Kidney Disease / End Stage Renal Failure?
Unresolved AKI (For 3 months - RF to ESRF)
CAKUT
Progressive renal insult from persistent proteinuria (induced fibrosis in Kidney), nephrotoxic drug use (NSAIDs) infections (HIV), tubular disorders etc.
What are the three systems for classifying AKI?
RIFLE, AKIN, KDIGO
All are based on changes in SCr from baseline (as proxy for GFR) or urine output
Rationale: To allow for standardized definition and comparison of results.
Also identify the patient who is at risk of kidney injury to allow for more stringent monitoring.
What are the general differences between the three classification systems?
RIFLE classifies AKI into 5 stages
AKIN and KDIGO classify AKI into 3 stages.
Additional 2 for RIFLE are just outcome measures.
Third criteria for KDIGO combines both RIFLE and AKIN
What does RIFLE define AKI (stage 1- Risk of Kidney dysfunction)as?
Increase in SCr of 1.5x (not 2)baseline (150% rise) or GFR decreases by 25% within 7 days
Or
Decrease in urine output of <0.5ml/kg/hr over >6 hrs (8hrs for children) -
Measure ace at least 2 times.
How many stages does RIFLE classify AKI into?
R- Risk of Kidney dysfunction I- injury to the Kidney F- Failure of Kidney function L- Loss of kidney function E- End stage renal failure (5 stages)
Stage 2 RIFLE classification for AKI (Kidney Injury)
SCr has risen by 2%, but not up to 3% (200% rise) or GFR decreases by 50% Or
Urine Output <0.5ml/kg/hr over >12 hrs
Stage F, L, ERIFLE definition of AKI
Scr has risen >/= 3x baseline (300% rise) OR GFR decreases by 75% OR Scr level > 350úmol/l or acute rise >44úmol/l
Or
Urine output of <0.3ml/kg/hr for 24 hours OR anuria for 12 hours
If it persists for 1 month, you’ve lost function (L) - need for RRT
If it persists for 3 months, you’ve gotten to ESRF (E) - need for RRT
How does AKIN define AKI?
An abrupt (within 48hours) absolute increase in Scr of >/= 26.4ûmol/l (0.3mg/dL) OR
%age increase in Scr of >/= 50% (I.e. baseline x1.5) OR
Oliguria of <0.5ml/kg/hr for >6hrs
AKI should only be diagnosed after achieving adequate hydration and after excluding any urinary tract obstruction.
Staging of AKI by AKIN Criteria
Stage 1
1.5 - 2 fold rise in Scr from baseline (150-200% increase) OR
Any absolute rise of >/= 26.4 ümol/l in 48 hours
Stage 2
>2-3 fold increase in SCr from baseline (200-300% increase)
Stage 3
>3 fold increase in SCr from baseline (>300% rise) OR
Any SCr >/= 354ümol/l with acute rise of at lease 44ümol/l
(Urine output criteria same as RIFLE)
How does the KDIGO criteria define AKI?
- Absolute rise in SCr of >/= 26.4 ûmol/l (0.3mg/dL) within 48 hours OR
- Increase in SCr of 1.5x baseline (%age rise in SCr of >/= 50%) within 7 days OR
- Oliguria of <0.5ml/kg/hr for > 24hours
KDIGO staging of AKI
Stage I: 1.5 to <2 fold increase in SCr from baseline
Stage II: >/=2 to <3 fold increase in SCr from baseline
Stage III: >/= 3 fold increase in SCr from baseline
Complications of AKI in Failure (RIFLE-F, AKIN III, KDIGO III)
Pulmonary edema (water imbalance) CCF Hypertension Hyperkalemia Acidosis Hyper PO42- & hypoCa2+ - convulsion Uraemia if azotemia is severe or prolonged Can lead to death
Treatment of AKI
Consider if the injury is pre-renal, intrinsic or post-renal
Pre-renal - There’s hypovolemia
*Fluid resuscitation (20ml/kg of NS). Repeat hourly if necessary for 1-2 doses
Intrinsic AKI (from tubular necrosis) Fluid restriction (if Oliguria). Insensible loss [400ml/m2/day] + previous day’s output. If markedly hypervolemjc and anuric, total fluid restriction + diuretic challenge.
Urethral catheterization (low obstruction at urethra)/other urinary diversion procedures for post-renal AKI. For high obstruction- nephrostomy for massive hydronephrosis Lower obstruction (PUV) - Vesicostomy
(Also direct treatment at primary cause)
How is Hyperkalemia from AKI treated?
*Myocardial stabilization (prevent cardiac arrest)
Ca gluconate 10% (0.5ml/kg IV over 5- 10 min). Protects heart from effect of K
*Intracellular K shift
B2 agonist e.g. Salbutamol (nebulize), epinephrine
NaHCO3
Insulin with Dextrose
*K elimination from the body
Kayaxelate (sodium polystyrene - switches Sodium for K)
Dialysis
*Supporting measures Avoid K-rich diet (banana, coconut, tomato) Avoid drugs (amoxiclav, AceI) that cause hyperK
Indication for Dialysis in AKI in Failure -1
*Failure of conservative mgt
Pulmonary edema unresponsive to diuretics
Hyperkalemia not controlled by conservative treatment
Severe metabolic acidosis (can cause heart to stop beating)
* Increase of >20% of initial body weight
* Prolonged Oliguria-Anuria (2-3days)
* Uraemic pericarditis
Indications for Dialysis - AKI in Failure 2
- Multisystem failure (liver, brain, kidney, septicemia)
- Uraemic encephalopathy
- Severe hyponatremia (<110mmol/l) or hypernatremia (>140mmol/l)
- Severe uraemia >30mmol/l of blood urea
- To make room for volume therapy (eg. Transfusion, TPN) in the oligo-anuric patient
