The Anatomical And
Physiological Peculiarities
Of Urinary Tract
In Children Of Different Age.
Renal structure and physiology
• The structural and functional
unit of the kidney is the nephron
• The nephron consists of:
 Bowman’s capsule, enclosing
the capillary tuft of the
glomerulus, which is joined
successively to the proximal
convoluted tubule,
 Henle’s loop,
 the distal convoluted tubule,
 the straight or collecting duct.
Longitudinal section of kidney
Embryogenesis
The kidneys develop from mesoderm
located between the somites and the
lateral portion of the embryo
Pronephros
• On the 21st day after fertilization the
mesoderm in the cervical region
differentiates into a structure called the
pronephros, which consists of a duct and
simple tubules connecting the duct with the
open celomic cavity. This type of kidney is
the functional adult kidney in some lower
chordates, but it is probably not functional
in the human embryo and soon disappears.
Mesonephros
• The mesonephros (middle kidney) is a
functional organ in the embryo. It consists
of a duct, which is a caudal extension of the
pronephric duct, and a number of minute
tubules, which are smaller and more
complex than those of the pronephros.
• One end of each tubule opens into the
mesonephric duct, and the other end forms a
glomerulus.
Formating of the uretra
• As the mesonephros is developing, the
caudal end of the hindgut begins to enlarge
to form the cloaca, the common junction of
the digestive, urinary, and genitale system.
The cloaca becomes divided by a urorectal
septum into two portions: a digestive
portion called the rectum and a urogenitalic
portion called the uretra.
Developing of ureter
• The mesonephric duct extends caudally as it
develops and eventually joints the cloaca.
At the point of junction another tube, the
ureter, begins to form.
Metanephros
• Metanephros starts to develop on the 3rd
month of gestation from the mesonephrotic
tubules and distal end of the ureter, which
enlarges and branches to form the duct
system of the metanephros.
• Metanephros is the adult kidney, which
takes over the function of the degenerating
mesonephros.
Congenital disorders of kidney development.
•Agenesia
•Aplasia
•Duplication
•Polycystosis
•Dystopia
•Hypoplasia
•Dysplasia
Aplasia of left kidney
Hypoplasia of left kidney
Lumbar, vertebra and pelvic
dystopia of kidneys
Anatomical perculiarities
of kidneys in infants
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Kidneys have relatively bigger sizes than in adults (1/100 of
body weight; 11-12 g);
The relation of thickness and length of kidney in newborn is 1:2
(in adult 1:3);
Lobular structure is present till 2 years age;
They are situated lower than in adult;
They have very thin fibrous capsule;
Absence of perirenal fat capsule in newborns leads to bad
fixation of kidneys and to physiological hypermobility of them
(in infants to 1.5-2.0 cm and in children older 7 years – 1-1.5
cm).
The cortex is undeveloped in neonates (thickness of cortex is ¼
of the medulla) comparing to school-age children and elder (it is
½ of the medulla).
Localization of kidneys
• Newborn – on the level of from 1st to 5th
lumbar vertebras.
• Older children – on the level between the
XІ thoracic and IV lumbar vertebras.
• The longer size of kidney is not bigger than
height of 4 lumbar vertebras.
• Right kidney is 1 cm longer than left one.
Localization of kidneys
according to vertebra column.
Age
On the left side
On the right side
The upper apex
Newborn
on the level of the lower edge
of ХІ thoracic vertebra
on the level of ХІІ thoracic
vertebra
3-5 months
on the level of ХІІ thoracic
vertebra
on the level of the lower edge
of ХІІ thoracic vertebra
1 year
on the level of the lower edge
of ХІІ thoracic vertebra
on the level of І lumbar
vertebra
2 years and older Like in adult
Like in adult
The lower apex
Below the iliac crest
Newborn
2 years and older Above the iliac crest
Ureters
• They are more wide and relatively longer in
children unders 7 years (dilated ureteres)
• They have the presence of physiological
kinks (twists), when they are situated near
the pelvic big vessels.
• Bad development of muscles layer under 3
years leads to often urine reflux from the
bladder.
• Mucus layer of ureters is wrinkled in
infants.
Urethral canal (urethra)
- Is wider and shorter in children under 3
years
- External urethral meatus is opened in girls
younger 3 years
Urinary bladder
• It is situated upper (in children under 3 years it can
be found above the interpubic joint, so it can be
palpable)
• The muscular leyer and elastic fibres are poorly
developed under 6 years
• Ureteric mouth (oribice) are commonly opened
due to undeveloped muscular sphincters.
That’s why vesicoureteric refluxes are very common
in children.
Very good vascularisation of bladder mucosa leads to
development of inflammatory processes of the
ureter and/or urine bladder.
Volume of the urinary bladder
Newborn
1 year
1-3year
3-5 year
5-9 year
9-12 year
Older
30ml
35-50 ml
50-90 ml
100-150ml
200ml
200-300 ml
400 ml
Length of the ureter
• newborn– 6-7 cm
• 1 year – 10 cm
• 4 year – 15 cm
• Older than 4 year – 20-28 cm
Morphological peculiarities of
glomerulus in children
• The differentiation of glomeruluses is not ended
• The glomerular epithelium in Bowman’s capsule
is cylindrical versus flat epithelium in adults
• The glomerular capillary endothelium is
composed of higher cells than in adults
• All peculiarities result in smaller filtrative surface
of kidney and lower permeability of glomerulus
barrier.
Morphological peculiarities of
tubules in children
• Relatively shorter and more narrow than in
adult, especially in the peripheral parts of
the kidney
• Henle’s loop is shorter and immature in
structure
Renal function
1. To maintain the chemical composition and volume of
the body fluids at a constant level.
2. To remove excess levels of waste products
(desintoxication).
3. The production of certain humoral substances:
 erythropoietic stimulating factor (ESF, or
erythrogenin), which acts on a plasma globulin to form
erythropoietin;
 renin, which is secreted by the kidneys in response to
reduced blood volume, decreased blood pressure, or
increased secretion of catecholamines;
 renin stimulates the production of the angiotensins,
which produce arteriolar constriction and an elevation
of blood pressure and stimulate the production of
aldosterone by the adrenal cortex.
3 processes that provide the
urine production:
• Providing an ultrafiltration of plasma.
• Reabsorption of the most part of fluid and
electrolytes from the primary urine by the
renal tubules.
• Secretion of certain substances into the
tubular urine.
Filtration of blood
• The plasma of the blood is filtered in the
glomerulus of capillaries
• The plasma pass into the capsular space (lumen)
and into the proximal tubules at a rate of about
125 ml/min/kidney.
• All from blood except the cells and the largest
elements (proteins) pass into original filtrate =
primary urine
• The primary urine has essentially the same
composition as plasma
Tubular absorption
• The pyramid-shaped cells of the proximal tubule
are responsible for absorption from the filtrate:
 85 % of the sodium chloride and water,
 all of the glucose,
 small proteins and amino acids,
 certain vitamins.
• The loop of Henle absorbs the water by drawing it
into the tissues between the tubules.
• the distal convoluted tubules and collecting ducts
absorb most of the water remaining so that 99 %
of original filtrate has been returned to the tissues
and 1 % passes into the minor calyces.
Secretion of certain substances into
the tubular urine
• Due tubular secretion some substances
appear in urine:
In the proximal tubule organic acids and
bases and H+ ions are secreted into lumen;
In the distal convoluted tubules and
collecting ducts secretion of Kalium ions
and NH3 takes place.
The peculiarities of kidney
function in early infancy
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Glomerular filtration rate is low and does not reach adult values
until the child is between 1 and 2 years of age
The concentrating ability of the newborn kidney does not reach
adult levels until about the third month of life.
Urea synthesis and excretion are slower during this time.
The newborn retains large quantities of nitrogen and essential
electrolytes in order to meet needs for growth in the first weeks
of life.
Newborn infants are unable to excrete a water load at rates of
older persons.
Hydrogen ion excretion is reduced.
Acid secretion is lower for the first year of life.
Infants have a diminished capacity to reabsorb glucose that
results in physiological glucosuria of neonates.
Infants have a diminished capacity to produce ammonium ions
during the first few days.
As a result of these inadequacies of
the kidney:
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the newborn is more liable to develop severe
acidosis.
kidneys are less able to adupt to deficiencies and
excesses of sodium. An isotonic saline infusion
may produce edema because the ability to
eliminate excess sodium is impaired. Conversely
inadequate reabsorption of sodium from tubules
may compound sodium losses in disorders such
as vomiting or diarrhea.
the newborn develops physiological anuria
during the first few days.
Patients complaints and methods of
physical examination
• The examination of kidneys is impossible
without laboratory urine tests.
• All symptoms in case of kidney disorders
are divided into renal and extrarenal.
Renal symptoms
• Renal symptoms are such clinical signs that
directly show on the disorders of kidneys and any
part of the collecting system
• They are:
 lumbar region pains (costovertebral angle
tenderness, flank pain)
 dysuria
 syndrom of urine changes
Causes of “kidney” pain.
• 1 – expansion of calyces
and renal pelvis;
2 – expansion of capsule;
3 – compression of
receptors;
4 – renal ischemia;
5 – refluxes.
• Only children after 2 years
can complain on lumbar
region pains, because in
this age cortex tissue and
renal capsule reach their
mature form.
Dysuria
•Dysuria means problems with urination:
painful urination;
frequent or infrequent voiding;
urinary urgency;
incomplete voiding;
enuresis.
Frequency of urination
• It is age-depended and closely connected with
fluid intake and surrounding climate (hot or cold).
• Voidind of the bladder is more frequent in infancy,
when it equals approximately the number of
feeding  3.
• For example: the 6 months baby empties the
bladder 53=15 times a day.
• At the age of 1 year urination frequency ranges
from 9 to 12 times a day, later it decreases to 6-8
times at 3 years, 5-6 times at 10 and 3-4 in
adolescence. Normal limits range within 1 to 3
times more or less.
Enuresis (urination incontinence)
• It is physiological in children up to 1.5 – 2
years.
• Enuresis can be daytime and nighttime.
• Toilet-trained child can perform
incontinence in case of urinary tract
infection or CNS disorders.
Syndrom of urine changes
• includes the interpretation of qualitative and
quantitative laboratory data of urine tests:
Colour of urine
Transparence
The urine volume (diuresis)
Specific gravity
Extrarenal symptoms
• Extrarenal symptoms are the signes, the cause of which is
kidneys disorders, but the developing pathological changes
concern other organs and systems.
• These are:
 Edema
 Hypertension.
 Cardiac pain.
 Skin pallor
 Intoxication syndrom includes fever, chills, anorexia,
fatigue, irritability, lethargy, headaches and vomiting.
 In infants kidney disorders can manifestate with feeding
problems and failure to thrive.
Kidney Edema
• develops as a result of fluid retention and disbalance of
intracapillary and tissue hydrostatic pressure.
• Visual evidence of fluid accumulation appears when the volume
of intersticial fluids enlarges more than on 15 %.
• The peculiarities of renal edema are:
 localization (puffiness of face, especially around the eyes);
 time of manifestation (they are more apparent in the morning and
subsides during the day);
 spreading (as the patient’s condition is getting worse edema
spreads to involve extremities and genital organs (labial or
scrotal swelling), abdomen (ascites), thoracic cavity
(hydrothorax). Edema of intestinal mucosal causes diarrhea,
anopexia, poor intestinal absorption. The total edema is called
anasarka.
 surface and concistency (skin above swelling is pale, warm and
soft by tuch).
Patient with kidney edema
Complex of diagnostic tests and
procedures
1. Urinanalysis (once per 7-10 days).
2. Nechiporenco, Amburgeau, Addis-Kakovskiy test.
3. Revealing of the so-called “active leukocytes” in
the urine sediment.
4. Urine culture with detection of microbe sensitivity
to antibiotics.
5. 3-glasses test.
6. Zimnitsky’s test
• Determination of secretory renal function: function of
distal tubules (ammonia, filtrated acidity of urine),
proximal tubules (α2-microglobulin in urine, calciuria,
phosphaturia), Henle’s loop (osmotic concentration of the
urine).
• Biochemical analyses of blood: total serum protein,
dysproteinemia (with elevated levels of α-and γ-globulins),
albumin/globulin ratio, cholesterol, residual nitrogen,
blood urea nitrogen, nonprotein nitrogen, creatinine, serum
sodium and other electrolytes, rise of ciliac acids,
mucoproteins, antistreptolysin-O, positive C-reactive
protein, total serum complement levels.
Tests to rule out structural
anomalies:
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Ultrasonography of kidneys and urinary bladder.
Intravenous pyelography.
Retrogradous urography.
Radiography.
Cystoscopy.
Cystography.
Renal biopsy.
Urinanalysis (Routine analysis of
urine)
• Qualitative characteristics of urine : colour,
smell and transparence;
• Quantitative characteristics of urine : pH,
specific gravity, urine chemistry (protein,
glucose, keton bodies, bile pigments,
urobilin etc.), microscopy of sediment
(leukocytes, erythrocytes, cylinders
(=casts), endothelial cells, mucus, pus and
bacteria).
Diuresis
• Diuresis means the process of urine
production.
• The urine volume (UV per 24 hrs) is its
laboratory reflection.
Daily diuresis
•Newborn
50 – 300 ml
•1 month infant
300 ml
•6 month infant
400 ml
•1 year child
600 ml
•1-10 years: UV = 600+100(n-1),where n is
age of child in years
•Older 10 years
1700 ml (varies with
intake and other factors)
Volume of 1 urination (voiding)
•Newborn – 10-15 ml
•6 mounth – 30 ml
•1 year – 60 ml
•3-5 years – 90-100 ml
•7-8 years – 150 ml
•10-12 years – 250 ml
Pathological changes of urine
volume.
• Poliuria is diagnosed when the urine volume exceeds the
normal ranges in 2 times and more.
• Oliguria means the decreasing of daily urine volume to ¼
of age ranges and less.
• Anuria is diagnosed when the urine volume decrease less
than 5 % of normal data or there is no urine per whole day.
It is one of the most dangerous conditions for the child’s
life and needs the emergency medical help.
 Renal – the kidneys don’t form the urine due to
consigerable damage of their tissues.
 Postrenal (mechanical) – the urine is produced, but it
doesn’t go into the bladder because of upper tract or
bladder neck obstruction.
Nocturia.
• The normal correlation of daytime and
nighttime urine volume is 2:1. That means
that because of bigger fluid intake and
physical activity urine excretion is more
intensive during daytime.
• If the night urine volume is bigger, it is the
manifestation of decreased renal function.
Specific gravity of urine
•It is the concentration of electrolits and other
substances dissolved in urine.
•Normal ranges are:
 Newborn 1.006-1.012
1-12 month – 1.002-1.006
2-5 years – 1.009-1.016
10-12 years – 1.012-1.025
•Excretion of 0.1 g of glucose per 1 l of urine
causes enlargement of specific gravity on 0.004;
0.4 g of protein – on 0.001.
Pathological changes of specific
gravity of urine.
• It is assessed by Zimnitskiy’s test
Maximal value of specific
gravity
Symptom
less than 1.008
hypostenuria
1.008-1.010
1.010-1.030
more than 1.030
isostenuria
Normal limits
hyperstenuria
Proteinuria
• Protein normally is absent in urine.
• But some amount up to 0.033 g/l is
permitted.
• Normal ranges of daily protein loss is 50 g
per day at rest and up to 100-130 g/day after
intense exercise.
• Excretion of protein with urine is called
proteinuria
– mild proteinuria up to 1 g/l is found in case of
cystitis, urine tract infection, after physical
exertion or getting cold;
– moderate proteinuria (1-3 g/l) develops in case
of glomerulonephritis, chronic renal failure,
renal tuberculosis;
– significant proteinuria (more than 3 g/l) is one
of the main signs of nephrotic syndrome or
terminal stage of renal failure.
Accordingly to source of protein in
urine:
•Renal organic proteinuria develops as a result of damage of
kidney’s tissue structure (for example, in case of
glomerulonephritis), when the filtration is enlarged.
•Renal functional proteinuria is the result of increased
permeability of glomerular endothelium or decreasing of blood
flow in responce to external influences:
albuminuria of a newborn appears due to functionally and structurally
immature glomerulus and significant loss of water with perspiration
immidiately after birth;
alimentary proteinuria develops after taking food rich with proteins;
orthostatic proteinuria is observed in toddlers and preschoolers after staying
for a long time in vertical position.
Functional proteinuria is less significant than organic and
disappears as soon as etiological factor stops its action.
•Extrarenal proteinuria appears in result of inflammatory processes
in the genitourinary tract (cystitis, urethritis, vulvovaginitis).
Microscopy of urine sediment
• It helps to find epithelial cells, RBCs and
WBCs, casts, salt crystals, mucus and
bacteria in urine.
• Epithelial cells are normally present in urine
sediment but not more than 2-4 cells in 1
square. The enlargement of their quantity
shows on inflammatory processes in urine
bladder or urethra (cystitis, urethritis etc).
Leucocyturia (or pyuria)
• WBCs are also present in urine of healthy person.
• If they are found in quantities more than 5-6 cells in
1 square in male and 10 cells in female, it is
leucocyturia (or pyuria) which is the evidence of
UTI.
• According to the source of leucocytes in urine there
are:
 renal leucocyturia (pyuria) is the evidence of urine
tract infection, acute or chronic pyelonephritis,
urethritis, cystitis, kidney TB, when WBCs go into
urine from organs of urinary system;
 extrarenal leucocyturia is diagnosed in case of
inflammatory processes of genital organs
(vulvovaginitis).
Haematuria
• RBCs are permitted to be found in urine but not more than
1-2 cells in 1 square.
• Presence of enlarged quantity of erythrocytes in urine is
called haematuria.
• It also can be renal and extrarenal.
• According to the quantity of found RBCs there are:
 microhaematuria (not more than 50 RBCs in 1 square). In
this case urine has its natural colour.
 macrohaematuria (more than 50 RBCs in 1 square). Urine
is reddish-brown or smoky brown, resembles tea or cola.
• If the urine is bright red, it means that it contains fresh
erythrocytes that is evidence of hemorrhage from kidneys
or any part of the collecting system.
Casts (cylinders)
• Casts (cylinders) are the moulds from cells or
molecules formed in renal tubules when the urine
flow in disturbed. Epithelial casts are formed from
ruined epithelial cells and are found in case of
severe renal disorders. Blood casts consist from
ruined erythrocytes and are present at
glomerulonephritis or renal bleeding. Leucocyte
cylinders are formed in case of pyelonephritis.
Quantitative methods
• These methods help to assess exact quantity
of RBCs, WBCs, and casts in patient’s urine
• They are:
Nechepurenko’s method
Method by Kakovsky-Addis
Ambyrze’s method
3-glasses test.
Bacteriological investigation
(urine culture)
• Technique of urine collection: collect 2-10 ml of
urine into sterile test-tube. Take urine from the
middle stream. Provide accurate intimate-wash of
child before collecting urine. Send urine to the
laboratory within 2 hours.
• Result is microbal number (the amount of bacteria
in 1 ml of urine) that normally not gets over
50 000.
• The result 10 000-50 000 is suspicious and
requires further examination.
• If microbal number is more than 50 000 that
means bacteriuria.
• Also the type of microflora is detalized (for
example, St. aureus, Proteus vulgaris, E. coli, etc)
and its sensitiveness to antibiotics.
Creatinine clearance (endogenous)
• This test helps to assess filtrative function of
kidneys.
• Endogenous creatinine is a substance that is
excreted from organism only by kidneys by the
way of filtration. The concentration of creatinine
in the blood serum is quitely constant as it does
not depend on food intake.
• Clearance is the amount of blood serum that is
completely cleared from the tested substance
during 1 min.
Technique of procedure:
• the child has to void the bladder in the morning
(at 8.00), and then to drink a glass of water (NO
BREAKFAST !);
– at 9 o’clock take a blood specimen for creatinine
concentration;
– at 10 o’clock the child has to void the bladder again (as
maximal as possible), in this urine creatinine
concentration is also measured.
• count the creatinine clearance according formula
Normal data of creatinine
clearance.
Age
Creatinine
clearance
Daily
creatinine
Newborn
40-65 ml/min/1.73 m2
8-20 mg/kg/d
Child
80-120 ml/min/1.73 m2
8-22 mg/kg/d
Adult
80-120 ml/min/1.73 m2
14-26 mg/kg/d
SEMIOTICS OF RENAL SYSTEM
DISORDERS
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Urinary tract infection (UTI)
Acute postsreptococcal glomerulonephritis
Acute renal failure
Chronic renal failure
Renal system disorders syndromes
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Disuria syndrome
Painful syndrome
Syndrom of urine changes
Edematic syndrome
Hypertension syndrome
Hypotension syndrome
Intoxication syndrome
Nephrotic syndrome
Nephrytyc syndrome
Cardiovascular system dysfunction syndrome
Anemic syndrome
Hemolytic-uremic syndrome
Enuresis (urinary incontinence) syndrome
• Nephrotic syndrome: massive proteinuria,
hypoproteinemia, hyperlipidemia,
hypersholesterinemia, edemas.
• Nephrytyc syndrome: hypertension,
hematuria, moderate proteinuria, edemas.