Kidney and Urinary Tract Disorders Flashcards
GFR at 28 weeks gestation compared to term infant
At 28 weeks the GFR is only 10% of term infant
GFR at term
15-20ml/min per 1.73m2
Changes in GFR post-partum
Rapidly rises to 1-2 years of age when adult rate of 80-120ml/min per 1.73m2 is reached
How are congenital renal abnormalities identified?
Before antenatal US they wouldn’t be detected until caused symptoms in infancy/childhood or occasionally adulthood - now detected in utero
What is renal agenesis?
Absence of both kidneys congenitally
What is Potters syndrome?
Oligohydramnios due to decreased urine production due to renal problems (as urine makes up majority of amniotic fluid) leading to fatal condition
Symptoms of Potters syndrome?
Specific facies with low-set ears, beaked nose, prominent epicanthic folds
Pulmonary hypoplasia
Deformed limbs
May be stillborn or die soon after birth due to resp. failure
Plasma Creatinine concentration in children
Main test of renal function
Rises progressively throughout childhood according to height and muscle bulk
eGFR in children
Better measure of renal function than creatinine and useful to monitor renal function serially in children with renal impairment
Inulin or EDTA GFR in children
More accurate as clearance from plasma of substrates freely filtered and not secreted or reabsorbed - but need for repeated blood tests limits use in children
Creatinine clearance in children
Requires timed urine collection and blood tests. Rarely done in children as inconvenient and inaccurate
Plasma urea concentration in children
Same as adults
Increased in renal failure often before creatinine starts rising, raised levels may be symptomatic
What is DMSA scan?
Static scan of renal cortex - detects functional defects such as scars but v.sensitive therefore need to wait 2 months after UTI
What is Micturating cystourethrogram?
MCUG - contrast into bladder through urethral catheter - visualise bladder and urethral anatomy - detects reflux and obstruction
What is MAG3 renogram?
Dynamic isotope scan - measures urinary drainage - best performed with high urine flow
In children >4 (can cooperate) can identify reflux
What is multicystic dysplastic kidney (MCDK)?
Results from failure of union of ureteric bud (ureter/pelvis/calyces/collecting duct) with nephrogenic mesenchyme
Therefore leaves non-functioning structure with multiple large fluid-filled cysts - no renal tissue and no collection to bladder
What happens normally to MCDK?
Half will have involuted by 2 years of age
Nephrectomy only indicated if remains large or hypertension develops (rare)
What is risk with MCDK?
Produce no urine therefore if bilateral will get Potters syndrome
Other causes of large cystic kidneys other than MCDK?
Autosomal recessive and autosomal dominant polycystic kidney disease and tuberous sclerosis
Difference between other cystic kidney disorders and MCDK?
Bilateral BUT some or normal renal function is maintained
Main symptoms of ADPKD in childhood?
Hypertension, haematuria
Renal failure in late adulthood
Extra-renal symptoms with ADPKD? x4
Cysts in liver and pancreas, cerebral aneurysms and mitral valve prolapse
What can abnormal caudal renal migration lead to x2 and possible consequence x2?
Pelvic kidney or horseshoe kidney (lower poles fused in midline) can predispose to infection or obstruction
What does premature division of the ureteric bud lead to?
Duplex system - can be bifid pelvis or complete division with two ureters
Consequence of duplex system x3
Ureters frequently have abnormal drainage so ureter from lower pole moiety often refluxes, whereas upper pole may drain ectopically into urethra or vagina or may prolapse into bladder - therefore obstruction
What is bladder extrophy?
Exposed bladder mucosa as a result of failure of fusion of infraumbilical midline
What is absent musculature syndrome/prune belly syndrome?
Absence or severe deficiency of anterior abdominal wall muscles - frequently associated with a large bladder and dilated ureters and cryptorchidism
Where can obstruction occur in boys?
Posterior urethra due to mucosal folds or a membrane called posterior urethral valves
What can occur in severe obstruction
Dysplastic kidney - small, poorly functioning and may contain cysts and aberrant embryonic tissue
Most severe = Potters syndrome
Antenatal treatment for obstruction
Intrauterine bladder drainage procedures have been attempted but results have been disappointing
Postnatal management of obstruction
Can start prophylactic antibiotics to prevent UTI
If bilateraly hydronephrosis detected in male then ultrasound within 48h to exclude posterior urethral valves
In females or if unilateral hydronephrosis then wait 4-6weeks before US to allow GFR and urine flow to increase because mild outflow obstruction may not be detected with low GFR
Management of posterior urethral valves
Cystoscopic ablation
Why is UTI in childhood important? x2
because up to 1/2 have a structural abnormality in urinary tract
and pyelonephritis may damage growing kidney leaving scars which predispose to hypertension and chronic renal failure if bilateral
UTI presentation in infants
Non-specific, fever normally always present, otherwise generally unwell, lethargy, vomiting, prolonged jaundice and poor feeding etc
UTI presentation in older children
Classical symptoms of loin pain, dysuria, enuresis and frequency become more common with increasing age
Different ways of obtaining a urine sample from a child?
Clean-catch sample when nappy is removed (recommended)
Adhesive plastic bag attached to perineum after careful washing
Catheter - if urgent
Suprapubic aspiration if child unwell
Nitrites in children
Positive result very likely UTI - but some can have nitrite-negative UTI
Leucocyte in children
May be present in UTI but may also be negative
May be present in febrile illness in child without UTI
Positive in balanitis and vulvovaginitis
Normal origin of bacteria causing UTI in children?
Usually from bowel flora unless neonate in which case it is usually haemotogenous
Bacterial cause of UTI in infant?x4
Most common is e.coli (80%)
But can also be proteus, pseudomonas, klebsiela and strep.faecalis
What dose proteus UTI predispose to
Formation of struvite stones - splits urea to ammonia and thus alkalinising the urine
What does pseudomonas UTI indicate
Presence of some structural abnormality hindering drainage
What is vesicoureteric reflux (VUR)?
Developmental abnormality at vesicoureteric junctions - ureters displaced laterally and enter directly rather than at angle therefore with short or absent intramural course
What can severe cases of VUR be associated with?
Renal dysplasia
Inheritance of VUR
familial with 30-50% chance of occurring in 1st degree relative
Variation in severity of VUR?
Can be mild reflux into end of undilated ureter during micturition to severest which is reflux during bladder filling and voiding - distended ureter and clubbed calyces
What can severe VUR lead to?
Intrarenal reflux (IRR) - very high risk of scarring if UTI occurs
What usually happens to VUR?
It usually resolves with age - especially low grade VUR
What is reflux nephropathy?
Small, scarred and shrunken poorly-functioning section of kidney
Management of child with UTI if atypical infection
Atypical = seriously ill, poor urine flow, abdominal/bladder mass, raised creatinine, failure to respond to antibiotics within 48hr, non-e.coli - then USS with DMSA and MCUG
Investigation of UTI
Ultrasound and MCUG (if abnormal USS findings)
Management of infants less than 3 months old with UTI
Hospitalised and IV antibiotics until temperature has settled and then oral antibiotics
Management of acute pyelonephritis/upper UTI in >3 months old (bacteriuria and fever or loin pain/tenderness even if no fever)
Co-amox, cefalexin or cefixime (over 6m)
7-10days
Management of lower UTI/cystitis in >3 months old
Oral ab’s eg. trimethoprin ,cefalexin or amoxicillin for 3 days
Prevention of UTI x7
High fluid intake
Regular voiding
Double micturition
Prevention of constipation
Good perineal hygiene
Lactobacillus acidophilus probiotic to reduce other organisms in gut
Antibiotic prophylaxis if under 2 years old with abnormalities of kidneys or urinary tract, upper UTI or severe reflux (trimethoprim)
What is daytime enuresis?
lack of bladder control during the day in a child old enough to be continent (3-5years)
Causes of daytime enuresis?x7
Lack of attention to bladder sensation Detrusor instability Weakness of bladder neck Neuropathic bladder UTI Constipation Ectopic ureter - constant dribbling
What is neuropathic bladder?
Distended/enlarged bladder - fails to empty properly, irregular thick wall
Associated with spina bifida and other neurological conditions
Investigation of daytime enuresis x5
Neurological exam US Urodynamic studies X-ray or MRI may show spinal abnormalities Microscopy, culture and sensitivity
Management of daytime enuresis if no neurological cause
Star charts, bladder training and pelvic floor exercises
If this fails then anticholinergic drugs to reduce bladder contractions eg. oxybutynin
What is secondary enuresis?
Loss of previously achieved urinary continence
Causes of secondary enuresis? x3
Emotional upset (commonest)
UTI
Polyuria from osmotic diuresis eg. DM or renal concentrating disorder eg. sickle or chronic renal failure
Investigation of secondary enuresis x3
Urine test for infection, glycosuria and proteinuria
Assessment of urinary concentrating ability by measuring osmolality of an early morning sample
US of renal tract
When can transient proteinuria occur in children?
During febrile illness or after exercise - does not require investigation
Common cause of persistent proteinuria in children? Diagnosis and management
Orthostatic proteinuria - only found when child is upright aka during the day
Diagnosed by measuring urine protein/creatinine ratio in series of early morning urine specimens
Prognosis is excellent no further investigation needed
Clinical signs of nephrotic syndrome x4
Periorbital oedema
Scrotal, vulval, leg and ankle oedema
Ascites
Breathlessness due to pleural effusions and abdominal distention
What occurs pathologically in nephrotic syndrome?
Heavy proteinuria results in low plasma albumin and oedema
What can be used to treat the majority of nephrotic syndromes in children?
85-90% of children with nephrotic syndrome - proteinuria resolves with corticosteroid therapy and therefore do not progress to renal failure = Steroid-sensitive nephrotic syndrome
Treatment regime in Steroid-sensitive nephrotic syndrome?
Oral steroids daily for 4 weeks and then reducing regime on alternate days until stopping
Response to steroids in SSNS
Usually urine is protein free after 11 days - but now good evidence that extending initial course of steroids can reduce relapse
Features suggesting SSNS x5
Age 1-10 years No macroscopic haematuria No hypertension Normal complement levels Normal renal function
Serious complications of nephrotic syndrome x4
Hypovolaemia (in extravascular space therefore intravascularly depleted - treat with IV albumin)
Thrombosis (loss of antithrombin in urine, thromocytosis increased with steroids, increased viscosity from raised haemotocrit)
Infection (esp. pneumococcus)
Hypercholesterolaemia (don’t know why)
Steroid-resistant nephrotic syndrome management?
Refer to specialist
Diuretics, salt restriction, ACEi and sometimes NSAIDs - for oedema
What is congenital nephrotic syndrome?
Presents in first 3 months of life - recessively inherited (consangueous families)
High mortality due to complications of hypoalbumnaemia rather than renal failure
Management of congenital nephrotic syndrome
May need nephrectomy - followed by dialysis until can have renal transplant
Signs of glomerular haematuria
Brown urine, presence of deformed red cells (as pass through BM), often with proteinuria
Signs of lower UT haematuria
Red colour, at beginning or at end
No proteinuria
Unusual in children
Most common cause of haematuria
UTI (usually not only symptom though)
Pathology of acute nephritis
Increased glomerular cellularity restricts blood flow and therefore decreased filtration
Symptoms of acute nephritis x4
Decreased urine output and volume overload
Hypertension (seizures)
Oedema esp. around eyes
Haematuria and proteinuria
What is post-streptococcal nephritis
Follows streptococcal sore throat or skin infection - common in developing countries but uncommon in developed - prognosis is good
What is Henoch-Schonlein purpura?
Combination of skin rash, arthralgia, oedematous joints (knees and ankles), abdominal pain and glomerulonephritis
When does Henoch-Schonlein purpura occur and in who? x4
Ages 3-10, peak in winter
More common in boys (x2)
Often preceeded by URTI
Presenting feature in Henoch-Schonlein purpura
Rash and fever
Where is rash found in HSP? and what sort
Buttocks Extensor surfaces of arms and legs Ankles Not on torso Maculopapular and purpuric
Joint pain in HSP x3 details
Occurs in 2/3rds - especially ankles and knees where there is periarticular oedema - no longterm damage to joints
Abdominal symptoms in HSP
Colicky abdominal pain - treated with steroids
GI petechiae can cause haematemesis and melaena
Intussusception can occur
Renal in HSP
Over 80% have microscopic or macroscopic haematuria or mild proteinuria
Not usually 1st symptom
Make complete recovery normally
If severe proteinuria in HSP
Nephrotic syndrome may result
Presentation of IgA nephropathy
Episodes of macroscopic haematuria
Associated with URTI
What is Alport syndrome? x4
Most common familial nephritis
X-linked recessive
Progresses to end-stage renal failure by early adult life in males
Associated with nerve deafness and ocular defects
Other vasculitis causing haematuria and other symptoms
Wegener disease - prominent involvement of respiratory tract
Also get fever, malaise, weight loss, skin rash and arthropathy
ANCA positive
Treatment of vasculitis causing haematuria eg. Wegeners x3
Steroids, plasma exchange and IV cyclophosphamide
Presentation of HTN in children x6
Vomiting, headache, facial palsy, convulsions, hypertensive retinopathy or proteinuria
Most common features of HTN in infants x2
Failure to thrive and cardiac failure
Causes of unilateral palpable kidneys x5
MCKD compensatory hypertrophy Obstructed hydronephrosis Renal tumour (Wilms) Renal vein thrombosis
Causes of bilateral palpable kidneys x4
ADPKD (adults) and ARPKD (children)
Tuberous sclerosis
Renal vein thrombosis
Which polycystic kidney disease presents with enlarged kidneys early in life
Recessive - associated with hypertension, hepatic fibrosis and progresses to chronic renal failure
Dominant is benign in childhood and renal failure onset is in adulthood
Commonest type of renal stones in children and cause?
Struvite stones caused by proteus
Stones which occur with most common metabolic abnormality in children?
Calcium stones occurring in idiopathic hypercalciuria - increased urinary urate and oxalate excretion
Presentation of renal stones in children x4
Haematuria, loin/abdominal pain, UTI or passage of stone
What is Fanconi syndrome?
Generalised proximal tubular dysfunction leading to inadequate reabsorption
What does Fanconi syndrome cause pathologically?
Excessive urinary loss of amino acids, glucose, phosphate, bicarbonate, sodium, calcium, potassium and urate
Presentation of Fanconi syndrome x5
Polydipsia and polyuria Salt depletion and dehydration Hyperchloraemic metabolic acidosis Rickets Failure to thrive/poor growth
Commonest type of acute kidney injury in children?
Prerenal
What occurs in renal acute kidney injury
Salt and water retention, blood/protein/casts often in urine
May be symptoms specific to the cause
Management of prerenal causes of AKI
Prerenal AKI is suggested by hypovolaemia therefore correct this - fluid replacement and circulatory support
Management of renal failure AKI
If circulatory overload then fluid restrict and diuretics to increase urinary output
Manage electrolyte imbalances
Treat cause - may need biopsy to identify it
Two commonest causes of renal failure AKI in children in UK
Haemolytic Uraemic Syndrome
Acute Tubular necrosis
Management of post-renal AKI
Relieve obstruction by nephrostomy or bladder catheterisation
Correct obstruction with surgery once fluid and electrolytes have been corrected
What is Haemolytic Uraemic syndrome (HUS)?
Triad of acute renal failure, microangiopathic haemolytic anaemia and thrombocytopenia
What is HUS typically caused by
Secondary to GIT infection with verocytotoxin producing E.coli
Acquired through farm animals or eating uncooked beef
Prodrome for HUS
Bloody diarrhoea
Pathology of HUS
Toxin localises to kidney - causes intravascular thrombogenesis
Coagulation cascade activated, normal clotting (unlike DIC) - platelets consumed - microangiopathic haemolytic anaemia occurs due to damage to RBC as pass through microcirculation which is occluded
What organs other than kidneys can be affected by HUS x3
Pancreas, brain and heart
Management of HUS
Early support and dialysis when prodrome of bloody diarrhoea can give good prognosis
Follow up needed
If no prodrome, may be familial and frequently relapses - high risk of HTN and chronic renal failure
Chronic kidney disease in children
Very rare
10 per million each year
Causes of chronic kidney disease in children
Congenital and familial are more common in childhood than acquired diseases
Clinical features of CKD in children x8
Anorexia and lethargy
Polydipsia and polyuria
Failure to thrive/grow
Bony deformities from renal osteodystrophy
HTN
Acute on chronic renal failure precipitated by infection/dehydration
Proteinuria
Unexplained normochromic, normocytic anaemia
Aims of management of CKD in children
Prevent symptoms and metabolic abnormalities of CKD to allow normal growth
Management of CKD against anorexia and vomiting
Calorie supplements, may need NGtube or gastrostomy
Protein intake should be sufficient
Pathology of renal osteodystrophy in CKD
Phosphate retention and hypocalcaemia due to decreased activation of vit D leads to secondary hyperparathyroidism - leading to osteitis fibrosa and osteomalacia
Management of renal osteodystrophy in CKD x3
Phosphate restriction (decrease intake of milk products) calcium carbonate as phosphate binder and vit d supplementation
Management of salt and water in CKD
Increased salt and water loss
Therefore salt supplements and water
Bicarbonate supplements to prevent acidosis
Cause and management of anaemia in CKD
Reduced production of erythropoeitin and circulation of toxic metabolites to bone marrow - therefore recombinant human erythropoietin given
Management of hormonal abnormalities in CKD
Recombinant human growth hormone given
Optimal management of CKD
Renal transplant preferably from living related kidneys (higher success rate) and before dialysis is required. But dialysis in the meantime can be given - need to have a minimum weight before transplant can occur to avoid renal vein thrombosis
