KIDNEY AND URINARY TRACT
Urinary Tract Anatomy
Kidney: Double organ, extra-peritoneal localization
Left kidney: (Th11-L2)
Right Kidney: (Th12-L3, 2-3 cm below Left Kidney)
Nephron structure:
 Glomerulus
 Proximal tubule:
o Convoluted tubule grad. First
o Thick part of descending branch of Henles loop
o Think part of Henles loop
 Distal tubule:
o Thick part of ascending branch of Henles loop
o Convoluted tubule grad. Second
o Collecting tubule
Kidney
Fetal kidney
Outer cortical glomeruli are relatively under perfused compared with
inner cortical glomeruli.
After birth renal perfusion to superficial cortical nephrons rises
compared with deeper glomeruli.
Glomerular Filtration Rate (GFR):
 Glomerular filtration rate begins between 9th and 12th week of
gestation.
 The GFR is relatively low at birth, especially in the premature
infant.
 The values of GFR nearly double between 3 and 7 days and
thereafter GFR continues to increase, by 1 and 2 years of age the
GFR is the same as in older child - 80% of the mature kidney.
 GFR 20-66 ml/min in newborn, increase twice in infants, 4
times in 2 years.
 80-140 ml/min in adults
GFR Equation:
eGFR = 0.413 x height (cm)/Creatinine (mg/dl)
Production of urine
Urine production begins at 8 weeks and it is estimated that at the
age of 10-12 weeks of gestation the fetal kidney will start to produce
urine (very dilute and small in amount)
Fetal urine is a major constituent of amniotic fluid and urinary flow
rate increases from 12 mL/hour at 32 weeks gestation to
28mL/hour in 40 weeks gestation. Similar increases are described
during the maturation of premature newborns.
Kidney of newborn
The kidney of the newborn infant has a limited capacity to regulate
the exertion of fluid and electrolytes
The high sodium excretion during the first 2 to 3 weeks often results
in a negative sodium balance: high risk of hypernatremia in infants
and younger children
Due to the poor ability to concentrate the urine (specific gravity 10021006) of the newborn there is a higher chance to get electrolyte and
fluid disorders in infants during the first 3 months.
The ability to concentrate urine will be correct after 6 months.
Daily diuresis:
 1-2 day: 30-60 mL
 3-10 day: 100-300 mL
 1 month: 150-400 mL
 2-12 month: 250-600 mL
 2-5 year: 500-700 mL
 6-14 year: 650 – 1400 mL
Frequency of dieresis:
During first days after birth (Below 6)
During six months of life, (about 15 to 25)
During preschool period, (about 6)
System of control of excretory of the urine works almost properly
about 3rd year of life.
Nocturnal enuresis is regarded to be pathology after 4th year of life
Pathology in Urinary System
 Pain
 Hematuria
 Proteinuria
 Hypertension
 Polyuria, Enuresis
 Oliguria, Anuria
 Edema
 Dysuria Symptoms
Proteinuria
Essential Proteinuria:
Over 4 mg/m2/hour proteins in 4 sample of urine or the urine
protein/Creatinine ratio in early morning sample reaches 0.25 (in
ml/mg)
Isolated Proteinuria:
Excretion proteins over 150 mg per day without any clinical or
laboratory symptoms during investigation.
Proteinuria:
In healthy children and adults rarely reach 100 mg/m2 for a day
Nephrotic Proteinuria:
Proteinuria over 50 mg/kg a day or 40 mg/m2/hour
Proteinuria Etiology:
 Glomerular abnormalities:
o Minimal changes disease
o Glomerulonephritis
o Abnormal glomerular basement membrane (familial
nephritis)
 Increased glomerular filtration pressure
 Reduced renal mass
 Hypertension
 Tubular proteinuria
 Orthostatic proteinuria
Hematuria
Hematuria microscopica (erythrocyturia):
More or equal to 5 red cell in urinary sediment under microscope
(x400)
Hematuria macroscopica:
More or equal to half of milliliter blood in liter of urine (Red colored
urine)
Etiology:
 Glomerular (crenated blood cells – erythrocytes):
o Acute glomerulonephritis (usually with proteinuria)
o Chronic glomerulonephritis (usually with proteinuria)
o IgA Nephropathy
o Familial Nephritis (e.g. Alport Syndrome)
o This Basement Membrane Disease
 Non-glomerular:
o Infection (Bacterial, Viral, TBC, Schistosomiasis)
o Trauma to Genitalia, Urinate tract, Kidney
o Stones
o Tumors
o Sickles Cell Disease
o Bleeding disorders
o Renal vein thrombosis
o Hypercalciuria
Edema
Definition:
An abnormal accumulation of fluid in extracellular, extravascular
space beneath the skin that produces swelling.
 Organ specific
 Generalized
Classic generalized edema in children (opposite to adults) is most of
ten du to:
 Renal disorders (main cause in children)
 Circulatory insufficiency (main cause in adults)
Renal Edema
Renal edema (especially in idiopathic Nephrotic syndrome) is due to
low albumin concentration in plasma (hipoalbuminemaia) and
decreased of osmotic plasma pressure (hypo-osmolality), what
leads to impaired removal of fluid to interstitial tissue.
Epidemiology:
Edemas are most often localized in the face (eyelids mainly), lower
limbs, and scrotum (in boys).
Quantity of edema can be measured by estimating weight increase
(for instance during Nephrotic syndrome)
Nephrotic Syndrome Symptoms:
 Heavy proteinuria
 Very low plasma albumin level
 Cholesterol increase (hypercholesterolemia)
 Generalized edema
Polyuria
Definition:
Diuresis over 1400/m2 body surface per 24 hours
Etiology:
 An excessive fluid intake
 Psychogenic Polydipsia
 Diabetes Insipidus
 Nephrogenic Diabetes Insipidus (Vasopressin –resistant Diabetes
insipidus)
Hypertension
Definition:
Hypertension is an increased blood pressure above 95th percentile
for height, age and sex.
Blood pressure in children need to be measured with a cuff over two
–thirds the length of the upper arm
Symptomatic hypertension in children is usually secondary to renal,
cardiac or endocrine causes.
Hypertension Etiology:
 Renal:
o Renal parenchymal disease
o Reno-vascular (e.g. Renal artery stenosis)
o Polycystic Kidney Disease (ARPKD or ADPKD)
o Renal tumors
 Coarctation of the aorta
 Catecholamine excess
o Pheochromocytoma
o Neuroblastoma
 Endocrine
o Congenital adrenal hyperplasia
o Cushing’s Syndrome or Corticosteroid Therapy
o Hyperthyroidism
 Essential hypertension
Enuresis
Primary nocturnal isolated enuresis (since birth with breaks shorter
than 6 months)
 Delayed control of vesicle bladder
 Prolonged use of diapers (lack of hygienic procedures)
 Emotional disorders
 Nocturnal polyuria (to much drinking in the evening)
 Immature system of daytime rhythm of antidiuretic hormone
secretion
 Insufficient functional capacity of urinary bladder
 Very deep sleep and problems with waking up
Secondary enuresis
The loss of previously achieved urinary continence
Etiology:
 Emotional upset – the commonest cause
 UTI
 Polyuria from an osmotic diuresis
 Diabetic mellitus
 Renal concentrating disorder (e.g. Chronic Renal Failure)
Daytime enuresis:
A lack of bladder control during the day in a child old enough to be
continent (over 5 years). Nocturnal enuresis usually is present too.
Etiology:
 Lack of attention to bladder sensation
 Detrusor instability or bladder neck weakness
 A neuropathic bladder
(associated with Spina Bifida or other neurological conditions)
 UTI
 Constipations
 Ectopic ureter
Oliguria and Anuria
Oliguria:
A decrease of diuresis under 300ml/1.73 m2 of body surface for a day
Anuria:
An absence of diuresis or diuresis under 100ml/1.73 m2 of body
surface per day.
Etiology of Acute renal failure (Oliguria)
 Prerenal:
o Hypervolemia (dehydration)
o Circulatory failure
 Renal:
o Vascular (interrenal)
o Tubular
o Glomerular
o Intestinal
 Postrenal (obstruction and strictures of excretory tract)
Dysuria Symptoms (difficulty in passing urine):
 Painful urination
 Frequent urination
 Vesicle urgency (sudden and painful feeling of excessive filling of
bladder (under underbelly) and necessity of immediate urination)
 Inconstancy of urine
UTI
Dysuric Symptoms: Typical for lower UTIs
Dysuric symptoms and Fever: Typical for upper UTIs
UTI Symptoms:
 Infants:
o Fever
o Vomiting
o Lethargy /irritability
o Poor feeding /failure to thrive
o Jaundice
o Septicemia
o Offensive urine
o Febrile convulsion (>6 months)
 Children:
o Dysuria frequency
o Abdominal pain or loin tenderness
o Fever with or without rigors (exaggerated shivering)
o Lethargy
o Failure to thrive
o Vomiting
o Diarrhea
o Hematuria
o Offensive/cloudy urine
o Febrile convulsion
o Recurrence of enuresis