Paediatric Nephrology Flashcards
Urine specimen collection techniques for paeds
Paedi bag: plastic sterile bag with stick edge, only useful if NEGATIVE, if positive must collect a clean specimen
Clean catch: catching midstream, unfavourable especially in non-circumcised boys
Suprapubic aspirate - finger breadth above pubic symphysis in the midline
Catheterisation
Categories of nocturnal enuresis
Primary: has not ever established 6 months of dryness
Secondary: have at some stage established dryness, and back to wetting
Monosymptomatic: wetting at night, no symptoms during the day
Non-monosymptomatic: day time symptoms (e.g. urgency, frequency, etc. more likely to be pathologic)
The most significant factor in treatment resistance in nocturnal enuresis
ADHD
Development of bladder control in children
Most children achieve bladder control by 5y
Familial tendency to later maturation of bladder control
Exposure to stressful events may induce children with previously good bladder control to recommence bed wetting
Common associations with nocturnal enuresis
Constipation UTI Family history Sleep disordered breathing (e.g. OSA or snoring) Epilepsy ADHD Diabetes Anorexia nervosa
Assessment of enuresis
Assess frequency Daytime symptoms (urgency, wetting, UTI, frequency) Bowels ?constipation Behaviour and peer relations Previous treatments and response Perform urinalysis to exclude UTI Investigations not usually indicated
When are investigations indicated in enuresis
After failure of initial treatment or daytime symptoms
ultrasound, uroflow and residual urine
Management of enuresis
ONLY BEGIN AFTER AGED 6
- Fluid restriction at night
- Empty bladder when parents ready to go to bed
- Incentive systems (star charts)
- Enuresis alarms (body worn alarm or pad and bell)
- Desmopressin (synthetic ADH) - if alarm therapy failed or contraindicated (ADHD) - melts are preferred, nasal spray associated with hypoNa
- Anticholinergics - Oxybutinin (if resistant to desmopressin, may use in combination if neither monotherapy is effective)
Conditions predisposing children to UTIs
Vesico-ureteric reflux Urinary obstruction (e.g. calculi secondary to cystinuria)
Common pathogens for paediatric UTIs
E Coli Proteus Klebsiella Enterococcus Staphylococcus
Management of UTI in a child
In well child: Oral Abx 5 days (10-14 if pyelonephritis present)
IV Abx if systemically unwell, vomiting oral medication or infant less than 6m
Prophylactic Abx if awaiting imaging results in a young child under 2
Definition of vesicoureteric reflux
Urine passing in a retrograde direction from the bladder through the vesico-ureteric junction into the ureter
Epidemiology of VUR
40% kids under 1y who are investigated for a first UTI have some degree of reflux (usually grade I or II)
Family trait affecting 30-50% of first-degree relatives of index cases
Higher grades are associated with higher recurrence rates of UTI +/- renal scars
Follow-up of UTI in infants
USS
MCU (micturating cysto-urethrogram) - indicated if normal USS or no obstruction on MAG3, will show VUR if present
DMSA (dimercaptosuccinic acid) “scars” - radionucleotide study, indicated 1-2 years after last UTI, reduced uptake of dye indicates scarring of kidney
DTPA (diethylene tramine penta-acetic acid) GRF
MAG3 (mercapto acetyl triglycine +/- captopril) - indicated if dilation of urinary tract, hydronephrosis or hydroureter on USS
Diagnosis of VUR
made by micturating cystourethrogram or by DMSA (radionucleotide study showing scarring of kidneys if reduced uptake)
Natural history of VUR
Most low-grade cases and up to 50% high-grade VUR will resolve by 4 years of age
- less likely to resolve if associated with other anomalies of the urinary tract e.g. duplication
Grading of vesicoureteric reflux
Grade I: reflux limited to ureter
Grade II: reflux up to renal pelvis
Grade III: mild dilatation or ureter and pelvicalyceal system
Grade IV: tortuous ureter with moderate dilatation, blunting of fornices but preserved papillary impressions
Grade V: tortuous ureter with severe dilatation of ureter and pelvicalyceal system, loss of fornices AND papillary impressions
Indications for surgical management of VUR
(ureteric reimplantation, disconnected from bladder and burrowed through multiple layers of bladder wall before reconnected - so that ureters close when bladder contracts)
High grade reflux and recurrent infections despite prophylactic antibiotics OR persistence of VUR beyond 5y
Causes of kidney disease in children
Birth defects: renal agenesis, dysplasia, ectopic kidney
Hereditary: Polycystic kidneys
Infection: HUS, post-strep GN
Nephrotic sydrome: minimal change disease, FSGS, membranoproliferative GN
Systemic disease: SLE, DM
Trauma: burns, dehydration, bleeding, injury, surgery
Urine blockage or reflux
Clinical presentation of post-streptococcal glomerulonephritis
10 days post pharyngitis OR 14 days post impetigo Gross haematuria Oliguric renal failure Hypertension Hypervolaemia Oedema
Investigations in post-streptococcal glomerulonephritis
Dysmorphic RBCs and RBC casts
Proteinuria (usually lower than nephrotic syndrome range)
Mildly elevated serum creatinine
Reduced complement (C3 and C4)
Evidence of streptococcal infection (skin lesion swab, Antistreptolysin O titre, anti DNAase B etc.)
Histological: diffuse inflammatory cells in glomerulus, deposition of neutrophils, IgG and complement. No necrosis
Management of post-streptococcal glomerulonephritis
Eliminate streptococcus infection with oral penicillins
Supportive therapy
Diuretics and ACE-i to control BP and extracellular fluid volume
Salt restriction and dialysis as necessary
Prognosis of post-streptococcal glomerulonephritis
Less than 1% progress to irreversible renal failure
Most recover to previous renal funciton levels within 3-4 weeks
Microscopic haematuria may persist for 3-6 months
Proteinuria falls at a slower rate than haematuria
Some patients experience persistent hypertension
Definition of IgA nephropathy
An immune complex-mediated glomerulonephritis characterised by IgA deposition in the glomerular mesangium
Genetic association with IgA nephropathy
HLA-DR4 in 50%
Cause of IgA nephropathy
Exaggerated marrow and tonsillar IgA immune response to viral/other antigens - mesangial deposits of IgA and IgA complexes, superimposed crescent formation - focal and segmental proliferative glomerulonephritis
Natural history of IgA nephropathy
25% spontaneous remission (usually those with mild haematuria and proteinuria)
15-40% have slow chronic progression to end-stage renal disease within 5-20 years
Common age group affected by IgA nephropathy
16-35 years
Clinical features of IgA nephropathy
Asymptomatic microscopic haematuria OR recurrent macroscopic haematuria sometimes following a viral URTI or GIT infeciton
Diagnostic investigations in IgA nephropathy
Urinalysis: RBC casts, +++ protein, +++ blood
Renal biopsy: proliferation of mesangial cells, increased cellularity in mesangium, immune complexes in mesangium on immunoperoxidase staining
Management of IgA nephropathy
All patients: ACE-I + ARB
Those with more than 1-3g/day proteinuria (with preserved GFR): steroids
Those with GFR less than 70: fish oil OR prednisolone + 3m of cyclophosphamide
Those with recurrent tonsillitis: tonsillectomy
Triad of haemolytic uraemic syndrome
Microangiopathic haemolytic anaemia
Thrombocytopaenia
Acute renal failure
Aetiology of HUS
Typical/endemic form AKA diarrhoea associated:
- most common
- preceded by enterohaemorrhagic e coli (EHEC)
- bacteria binds to endothelium, produces verotoxin which primarily attacks capillaries in kidneys - haemolysis of RBCs and damage of kidney parenchyma
ATYPICAL/sporadic form AKA diarrhoea negative HUS
- unclear aetiology
-?inherited condition of endothelial tissue within kidneys
Most common cause of intrinsic renal failure in paediatrics
Haemolytic uraemic syndrome
Clinical presentation of haemolytic uraemic syndrome
Diarrhoeal illness (+fever, vomiting etc.) for 7-10 days
Then develops:
- Pallor
- Petechiae (DIC)
- Oliguria
- Oedema
- CNS signs (sleepiness, agitation, convulsions)
Investigations in HUS
Haemolytic anaemia - schistocytes/fragment cells on film - low Hb - increased bilirubin Thrombocytopaenia Negative Coombs test (not autoimmune haemolysis) Proteinuria Haematuria with casts Acute kidney injury on EUC DIC
Management of HUS
Essentially supportive management:
- Dialysis
- Fresh frozen plasma (DIC) +/- blood transfusions
- Antihypertensives to reduce proteinuria
Prognosis in HUS
Better in infants v older children
- AKI often lasts about 2 weeks, sometimes slowly progresses to CKD
- 25% mortality of acute period
- Poorer prognosis in diarrhoea negative HUS (recurrent HUS presentations, some will require transplant)
