1. Risk factors of nephrolithiasis among
children
Ahmad Ali Nikibakhsh
Pediatric Nephrologist
Urmia University of Medical Sciences

2. Risk factors of nephrolithiasis among
children
• The prevalence of kidney stones in different parts
of the world is reported 1% - 15%
• in Iran the incidence of kidney stones is 1.7% -
4.1% in children aged 4 to 9 years; whereas, in
America it is one in 100,000 children.
• Iran is on the kidney stone belt
• Mohkem M, Mahani F, Otokesh B, Sharifiyan M, Delirani R, Hatemiyan B. Epidemiological
investigation of urolithasis in children hospitalized children over 5 years of useful .
Pajoohandeh J. 2010
• Sas DJ. An update on the changing epidemiology and metabolic risk factors in pediatric
kidney stone disease. Clin J Am Soc Nephrol. 2011

3. Risk factors of nephrolithiasis
• A geographical ‘stone belt’ extending from the
Balkans across Turkey, Pakistan and northern
India is characterised by a high incidence of
endemic bladder stones in children.
• Chronically inadequate dietary intake of protein
• Relative dehydration associated with the climate,
malnutrition, diarrhoeal illness
• dietary phosphate deficiency
• Patrick G Duffy Stone disease in children
ESSENTIALSOF PAEDIATRIC UROLOGY SECOND EDITION

4. Risk factors of nephrolithiasis
• Nephrolithiasis is multifactorial process (medical
history, imaging tests, stone analysis, metabolic study
and physicochemical urine analysis).
• All these investigations should be evaluated together
• In half of all patients, stone formation is secondary to
the presence of metabolic alterations in urine, of which
the most frequent is idiopathic hypercalciuria.
• The second most frequent cause is infection and/or
urinary malformations, while hereditary enzyme
defects are highly unusual
• Cameron MA, Sakhaee K, Moe OW (2005) Nephrolithiasis in children. Pediatr
Nephrol

5. Factors involved in stone formation
• Urinary concentration, ionic activity and
solubility of stone-forming constituents.
• This process is influenced by the urinary
excretion rate of the stone-forming substance,
the level of hydration and the urinary pH.
• Presence of abnormal urinary metabolites or
pathologically elevated concentration of
normal urinary constituents
• Patrick G Duffy Stone disease in children
ESSENTIALSOF PAEDIATRIC UROLOGY SECOND EDITION

6. Urinary infection
• Certain bacterial species, notably Proteus,
Klebsiella and Pseudomonas, are capable of
the enzymatic splitting of urea to produce
NH3, with consequent elevation of the urinary
pH and precipitation of ammonium salts.
• Infection is also a key factor in the produc-
tion of the proteinaceous matrix component
of calculi.
• Patrick G Duffy Stone disease in children
ESSENTIALSOF PAEDIATRIC UROLOGY SECOND EDITION
•

7. Anatomical abnormalities of the
urinary tract
• Stasis of urine within an obstructed or dilated urinary tract
creates an environment in which stone-forming substances
are more likely to precipitate
• This process can occur in sterile urine, but not uncommonly
infection and stasis coexist.
• Micturating cystography (MCU) is not routinely required.
However, when ureteric dilatation persists postoperatively,
or in the event of further infection, an MCU should be
performed.
• Infection and the passage of stone material to the bladder
may result in transient VUR, which resolves once the
infection has been treated and stone clearance achieved.
• Patrick G Duffy Stone disease in children
ESSENTIALSOF PAEDIATRIC UROLOGY SECOND EDITION

8. Prematurity
• Premature children (born at less than 37 completed weeks’
gestation) are at much greater risk of nephrocalcinosis and
nephrolithiasis.
• Approximately 20% of babies born under 32 weeks’ gestation
develop nephrocalcinosis and 5–9% have calculi.
• The risks are increased with increasing prematurity of birth,
decreasing birth weight, co-morbidity and the use of furosemide,
thiazides and other drugs.
• Premature and formula-fed babies have increased solute excretion
(e.g. oxalate).
• Babies receiving parenteral nutrition have a higher oxalate and
calcium but lower citrate excretion, contributing to higher calcium
oxalate saturation.
• Patrick G Duffy Stone disease in children
ESSENTIALSOF PAEDIATRIC UROLOGY SECOND EDITION
•

9. Metabolic disorders in the urinary analysis Of
patients with urolithiasis 2002 tO 2012
(hospitalized)
• Hypercalciuria (74.6%) Hypocitraturia (44.1%)
Hyperuricosuria (30.5%) Hyperoxaluria (8.5%)
Cystinuria (5.1%) Hyperphosphaturia (1.7%)
Hypomagnesuria (1.7%)
• Hypercalciuria + Hypocitraturia (14.5%)
Hypercalciuria + Hyperuricosuria (12.72%)
Hypercalciuria + Hypocitraturia + Hyperuricosuria
(12.72%)
• Luana Amancio ,Maira Fedrizzim. Pediatric urolithiasis: experience
at a tertiary care pediatric hospital
•

10. Harika Alpaym. Clinical and metabolic features of urolithiasis and
microlithiasis in children Journal of Pediatric Nephrology 2009
Metabolic evaluation Percentagea
Hypercalciuria 33.8
Hypocitraturia 33.1
Hyperoxaluria 26.5
Hyperuricosuria 25.4
Hypocitraturia + hypercalciuria 21.1
Hyperphosphaturia 20.8
Cystinuria 5.7
Normal metabolic examination 13.1

11. • Hypercalciuria was the most common (31
patients, 29.8%), followed by hyperuricosuria (27
patients, 26%), hyperoxaluria (20 patients,
19.2%), hypocitraturia (13 patients, 12.5%), and
cystinuria (one patient, 0.96%).
• Hyperuricosuria (88.9%) and hypocitraturia
(46.2%) were more common in infants younger
than 12 months old compared to those older
• Abolhassan Seyezadeh .Prevalence of Metabolic Risk Factors
AffectingChildhood Nephrolithiasis Int J Pediatr 2020
•

12. Nephrocalcinosis is defined as calcification
located in the renal parenchyma.
• is an important finding in children, but it still
remains under- or misdiagnosed in high
proportion of patients.
• All children with NC should be evaluated
carefully.
• Early diagnosis, treatment, and regular follow-
ups should be performed
• F. Şemsa Altugan ,Medullary nephrocalcinosis in a pediatric patient Journal
Pediatric Nephrology2009

13. Common causes of medullary
nephrocalcinosis
Common causes of medullary nephrocalcinosis
Hypervitaminosis D Hyper/hypothyroidism Chronic pyelonephritis
Cushing’s syndrome Hyperparathyroidism Medullary sponge kidney
Sarcoidosis Malignancy Nephrotoxic drugs
Sickle cell disease Bone metastases Idiopathic hypercalcemia
Primary hyperoxaluria Renal tubular acidosis
Hypercalciuric states
Dent’s disease
Familial hypomagnesemia
with hypercalciuria and
nephrocalcinosis
Bartter syndrome
Williams–Beuren
syndrome

14. Microlithiasis
• Renal microlithiasis or microcalculi (RM) is defined as
ultrasonographic detection of hyperechogenic deposits
smaller than 3 mm in diameter in renal calyces, pelvis
or ureter.
• There are only few reports on diagnosis, investigation,
management, long term follow-up and final outcome
of RM.
• RM is a separate entity which is more frequent in
younger children and especially in infants
• RM can be detected in first few months of life and even
in the neonatal period and might be the source of late
childhood renal stone
• Polito C, Apicella A, Marte A, Clinical presentation and metabolic features of
overt and occult urolithiasis. Pediatr Nephrol. 2012;

15. underlying disorders
• Urinary tract infection is a significant cause or
complication of renal stone in children; however, its
role in RM is not so clear.
• Elevated serum levels of vitamin D may have a
significant role in infants with stone formation and
RM
• Different anatomical anomalies of the kidneys and
urinary tract : in a large series of 511 pediatric
patients with urolithiasis, 12% had anatomical
abnormalities.
• Rizvi SA, Naqvi SA, Pediatric urolithiasis: J Urol. 2002

16. Metabolic evaluation
• Hypercalciuria and hypocitraturia are the most
commonly reported metabolic abnormalities
• complete metabolic evaluation is indicated in all
children with nephrolithiasis and RM
• In a study on 153 infants and children with renal
stone, 90.8% had at least one metabolic
abnormality with hypomagnesiuria and
hypocitraturia as the most common findings
• Fallahzadeh MH, Sedighi V, Basiratnia M, et al.A report on metabolic
evaluation of 153 children with urolithiasis. Pediatr Nephrol. 2010