Nephrology Flashcards
What are UTIs?
Infections anywhere along the urinary tract pathway including the urethra, bladder, ureters and kidneys.
What is acute pyelonephritis?
Infection affecting the tissue of the kidney.
It may lead to scarring and consequently a reduction in renal function.
What is cystitis?
Inflammation of the bladder; may be a result of a bladder infection.
What may be the only symptom of a UTI in young children?
Fever.
Always exclude/consider a UTI in a child with a temperature unless clear alternative source of infection.
How may babies present with a UTI?
Non-specific symptoms.
- fever
- lethargy
- irritability
- vomiting
- poor feeding
- urinary frequency
How may older infants and children present with a UTI?
More specific symptoms than babies.
- fever
- abdominal pain (particularly suprapubic pain)
- vomiting
- dysuria
- urinary frequency
- incontinence
What features are required to diagnose acute pyelonephritis?
- temperature >38C
- loin pain or tenderness
What key investigation is required if suspect a UTI?
Urine Dipstick
- clean catch sample, avoiding contamination
- involves parent sat with infant without a nappy and a urine pot held ready to catch the sample if it occurs
Midstream urine (MSU) sample to microbiology to be cultured and have sensitivity testing.
What two aspects of a urine dipstick are important for UTI?
Nitrites
Leukocytes
Why are nitrites used as a marker?
Gram negative bacteria (e.g. E.Coli) break down nitrates (a normal waste product in the urine) into nitrites.
The presence of nitrites on a urine dipstick therefore suggests bacteria in the urine.
Why are leukocytes used as a marker?
There are normally a small number of leukocytes in the urine, however a significant rise may indicate infection or another cause of inflammation.
A urine dipstick tests for leukocyte esterase, an enzyme released by leukocytes (neutrophils, macrophages) giving an indication of the number of leukocytes in the urine.
Which of nitrites and leukocytes is the better indication of infection?
Nitrites.
What should be done if only nitrites or only leukocytes or both are found?
Nitrites - worth treating as UTI.
Leukocytes - do not treat as UTI unless there is clinical evidence they have one.
Nitrites & leukocytes - treat as a UTI.
If either are present, send MSU sample to microbiology.
How should a child <3 months with a fever and UTI be managed?
- immediately start IV antibiotics e.g. ceftriaxone
- full septic screen (blood cultures, bloods, lactate)
- consider lumbar puncture
How should a child >3 months with a fever and UTI be managed?
- oral antibiotics (if otherwise well) e.g. trimethoprim, nitrofurantoin, amoxicillin, cefalexin
- features of sepsis or pyelonephritis requires inpatient treatment with IV abx
- Treat pyelonephritis with IV cephalosporin
What investigations can be used for recurrent UTIs?
1) Abdominal USS
2) DSMA Scan
3) MCUG (micturating cystourethrogram)
When should an USS be done for children?
- do abdo USS within 6 weeks in all children <6 months with first UTI (or during illness if recurrent UTIs or atypical bacteria)
- abdo USS within 6 weeks in children with recurrent UTIs
- abdo USS during illness in children with atypical UTI
What is a DMSA scan used for, how does it work, and when should it be done?
Assesses renal scarring (static function).
Use 4-6 months after illness to assess for damage from recurrent or atypical UTIs.
Inject radioactive material (DMSA); use a gamma camera to assess how well the material is taken up by the kidneys.
Where there are patches of kidney that have not taken up the material, this indicates scarring that may be the result of previous infection.
Gives a split function of kidneys - normal would be 50% in each kidney (accept 45-50%)
What is vesico-ureteric reflux (VUR)?
Where urine has a tendency to flow from the bladder back into the ureters.
What does VUR predispose patients to?
Developing upper urinary tract infection and subsequent renal scarring.
How is VUR diagnosed?
Micturating cystourethrogram (MCUG).
How is VUR managed?
Depends on severity.
- avoid constipation
- avoid excessively full bladder
- prophylactic abx
- surgical input from paediatric urology
What can micturating cystourethrograms be used to investigate?
- atypical or recurrent UTIs in children <6 months
- family history of VUR
- dilatation of the ureter on ultrasound
- poor urinary flow
What is involved in a micturating cystourethrogram?
- catheterise child
- inject contrast into the bladder
- take series of xray films to determine whether contrast is refluxing into the ureters (diagnose VUR)
- give prophylactic abx for 3 days around time of investigation
What does enuresis mean?
Involuntary urination.
What is the term for bed wetting?
Nocturnal enuresis.
What is the inability to control bladder function during the day called?
Diurnal enuresis.
What is the normal age for children to get control of daytime urination?
2 years.
What is the normal age for children to get control of night time urination?
3-4 years
What is Primary Nocturnal Enuresis?
Where the child has never managed to be consistently dry at night.
What is the most common cause of Primary Nocturnal Enuresis?
Variation on normal development, particularly if the child is <5 years old.
Family history of delayed dry nights.
- important to reassure, no need for further investigations/management
What are other causes of primary nocturnal enuresis?
1) Overactive bladder (frequent small volume urination prevents development of bladder capacity)
2) Fluid intake prior to bedtime (fizzy drinks, juice, caffeine have diuretic effect)
3) Failure to wake due to deep sleep and underdeveloped bladder signals
4) Psychological distress (low self-esteem, pressure/stress at home/school)
5) Secondary causes e.g. chronic constipation, cerebral palsy, learning disability, UTI
How is Primary Nocturnal Enuresis managed?
1) Establish underlying cause - 2 week diary of toileting, fluid intake, bedwetting episodes; good history and examination to exclude physical/psychological causes
2) Reassure parents of children <5 years that likely to resolve without treatment
3) Lifestyle changes e.g. reduce fluid intake in evenings, pass urine before bed, easy access to toilet
4) Encouragement and positive reinforcement (avoid blame/shame/punishment)
5) Treat underlying causes/exacerbating factors e.g. constipation
6) Enuresis alarms (sensor wakes child if wet)
7) Pharmacological treatment
What is Secondary Nocturnal Enuresis?
Where a child begins wetting the bed when they have previously been dry for at least 6 months.
More indicative of underlying illness than primary enuresis.
What are causes of secondary nocturnal enuresis?
- UTI
- constipation
- T1DM
- new psychosocial problems (e.g. stress in family/school life)
- maltreatment
- consider abuse and safeguarding e.g. with deliberate bedwetting, punishment for bedwetting or unexplained secondary nocturnal enuresis
What is the management for secondary nocturnal enuresis?
- treat underlying cause
- may require referral to secondary care
What is diurnal enuresis?
Daytime incontinence - child has become dry at night but still has episodes of daytime urinary incontinence.
Who does diurnal enuresis most commonly occur in?
Girls.
What are the causes of diurnal enuresis?
- urge incontinence (overactive bladder that gives little warning before emptying)
- stress incontinence (leakage of urine during physical exertion, coughing, laughing)
- recurrent UTIs
- psychosocial problems
- constipation
- voiding dysfunction (learned behaviour of deliberately holding urine as busy playing)
What is an enuresis alarm?
Device that makes a noise at the first sign of bed wetting, waking the child and stopping them from urinating.
Requires high level of training and commitment,
Needs to be used consistently for a prolonged period (e.g. at least 3 months).
What pharmacological management is available for nocturnal enuresis?
1) Desmopressin (ADH analogue) - reduces volume of urine produced by the kidneys
2) Oxybutinin (anticholinergic) - reduces bladder contractility, helpful in overactive bladder causing urge incontince
3) Imipramine (TCA) - mechanism unclear but may relax bladder and lighten sleep
What is nephrotic syndrome?
It is when the basement membrane in the glomerulus becomes highly permeable to protein, allowing proteins to leak from the blood into the urine.
What ages is nephrotic syndome most common in children?
2-5 years
Give some features of nephrotic syndrome.
Frothy urine
Generalised oedema
Pallor
What is the classic triad of nephrotic syndrome?
1) Low serum albumin
2) High urine protein content (>3+ on urine dipstick)
3) Oedema
What other features may occur in patients with nephrotic syndrome?
- deranged lipid profile (high levels of cholesterol, triglycerides, low density lipoproteins)
- high BP
- hypercoaguability (with increased tendency to form blood clots)
What is the most common cause of nephrotic syndrome in children?
Minimal change disease
- Causes >90% cases in children <10 years
- nephrotic syndrome occurs in isolation in minimal change, without any clear underlying condition or pathology
What are some secondary causes of nephrotic syndrome?
Secondary to intrinsic kidney disease:
- focal segmental glomerulosclerosis
- membranoproliferative glomerulonephritis
Secondary to underlying systemic illness:
- Henoch schonlein purpura (HSP)
- Diabetes
- Infection e.g. HIV, hepatitis, malaria
What will urinalysis show in minimal change disease?
- small molecular weight proteins
- hyaline casts
How is minimal change disease managed?
- corticosteroids (prednisolone)
Good prognosis, most children make full recovery
May reoccur.
How is nephrotic syndrome managed?
Managed by experienced paediatricians with input from renal specialists.
- high dose steroids (prednisolone)
- low salt diet
- diuretics (treat oedema)
- albumin infusion (severe hypoalbuminaemia)
- antibiotic prophylaxis (severe cases)
How long should high dose steroids be given for in nephrotic syndrome in children?
- for 4 weeks then gradually weaned over next 8 weeks
Will all children respond to steroids in nephrotic syndrome?
80% children respond to steroids (steroid-sensitive)
80% steroid sensitive patients will relapse at some point and need further steroids
What do steroid dependent and steroid resistant mean?
Steroid dependent - patients struggle to wean steroids due to relapses
Steroid resistant - patients do not respond to steroids
What can be used for steroid resistant children in nephrotic syndrome?
ACEi
Immunosuppressants e.g. cyclosporin, tacrolimus, rituximab
What are complications of nephrotic syndrome?
- hypovolaemia
- thrombosis
- infection
- acute/chronic renal failure
- relapse
Why can hypovolaemia occur in nephrotic syndrome?
Fluid leaks from the intravascular space into the interstitial space (due to oncotic pressure) causing oedema and low BP.
Why can thrombosis occur in nephrotic syndrome?
Proteins that normally prevent blood clotting are lost in the kidneys.
Liver responds to low albumin by producing pro-thrombotic proteins.
Why can infection occur in nephrotic syndrome?
The kidneys leak immunoglobulins, weakening the capacity of the immune system to respond.
Exacerbated by treatment with medications that suppress the immune system e.g. steroids.
What is nephritis?
Inflammation within the nephrons of the kidneys.
What does nephritis cause?
- reduced renal function
- haematuria (visible or non-visible)
- proteinuria (less than in nephrotic syndrome)
What are the two most common causes of nephritis in children?
1) Post-streptococcal glomerulonephritis
2) IgA nephropathy (Berger’s disease)
What does post-streptococcal glomerulonephritis follow?
Occurs 1-3 weeks after a beta-haemolytic streptococcus infection (e.g. tonsilitis caused by Streptococcus pyogenes)
How does post-streptococcal glomerulonephritis lead to nephritis?
Immune complexes made up of streptococcal antigens, antibodies and complement proteins get stick in the glomeruli of the kidney and cause inflammation.
Inflammation leads to acute deterioration in renal function leading to an AKI.
What blood test can be carried out to test for recent streptococcus infection?
Anti-strepsolysin O (ASO) titre
ASO is an antibody targeted against streptolysin O, a toxin produced by Group A streptococcus bacteria (e.g. S. pyogenes)
What is the management for post-streptococcal glomerulonephritis?
- supportive management (80% make a full recovery)
- some patients may develop progressive worsening of renal function = antihypertensives if develop HTN; diuretics if develop oedema
What is an alternative term for IgA nephropathy?
Berger’s disease
What condition is associated with IgA nephropathy?
Henloch-Schonlein Purpura (a IgA vasculitis)
How does IgA nephropathy cause nephritis?
IgA deposits in the nephrons of the kidney causes inflammation causing nephritis.
What will a renal biopsy show on histology for IgA nephropathy?
IgA deposits
Glomerular mesangial proliferation
What ages does IgA nephropathy tend to occur?
Teenagers
Young adults
What is the management for IgA nephropathy?
Supportive treatment of renal failure
Immunosuppressants e.g. steroids, cyclophosphamide to slow disease progression
What methods are there for obtaining a urine sample in infants?
- Clean catch (best option)
- Sterile bags
- Pads
- Sterile container given to parents (opportunistic)
- Stimulate hypogastric region and lower spine
Less commonly:
- Catheter
- Suprapubic aspirate
When is it appropriate to send a urine culture despite negative nitrites and leukocytes?
In neonates - ALWAYS send urine culture.
What % of UTIs are typical? Which organism is involved?
85-90%
E. Coli/Coliforms.
What organisms are atypical UTIs?
Non-E.Coli
E.g. Klebsiella, pseudomonas
Which of nitrofurantoin and trimethoprim have a narrow spectrum?
Trimethoprim.
Why is it good to give a narrow spectrum abx?
To reduce risk of resistance
When is nitrofurantoin best used?
As a ‘back up’
In difficult to treat UTIs and recurrent UTIs
What is a MAG3 renogram and what is it used for?
Radiolabelled MAG3 injected, followed by a diuretic to then assess the excretory capability of the kidneys - dynamic function.
Able to visualise pelvic ureteric junction (PUJ) obstruction.
What are posterior urethral valves? Who does it occur in?
Obstructive membranes that develop in the urethra near the bladder (valves) that can obstruct of block the outflow of urine through the urethra.
What causes posterior urethral valves?
Usually sporadic, although some cases have been seen in twins and siblings suggesting genetic component.
Develops in early stages of foetal development in utero.
Who does posterior urethral valves affect?
Male infants.
Around 1 in 8000 births.
How may posterior urethral valves present?
- UTI
- weak urine stream
- urinary dribbling
- difficulty with urination
- urinary frequency
- new onset urinary incontinence
What may posterior urethral valves cause?
Hydronephrosis
Hydroureter
(Progressive dilatation of the bladder, ureters, kidneys)
What investigations can be done for posterior urethral valves?
- prenatal scanning (hydronephrosis may be identified; monitor baby throughout pregnancy and after birth)
MCUG (diagnoses VUR)
USS KUB
U&Es (renal function)
How are posterior urethral valves managed?
Surgery
- valve ablation (via cystoscope)
- vesicostomy (lower abdominal opening to drain urine freely - temporary if baby too small or severe obstruction)
