Urinary phytate (Myo-inositol hexaphosphate) in healthy school children and risk of nephrolithiasis.
OBJECTIVE
Although the incidence of urolithiasis is lower in children than in adults, the number of children with urolithiasis is increasing. Phytate, a naturally occurring compound present in legumes, nuts, and whole meals, has antilithiasic activity. The aim of this study was to assess, for the first time, the urinary levels of phytate in children and to correlate these levels with other urinary parameters related to crystallization risk and to general dietary habits.


METHODS
This was a cohort study conducted from April 2012 to March 2013 in the Laboratory of Investigation in Renal Lithiasis and at Son Espases Universitary Hospital in Palma de Majorca, Spain.


METHODS
Subjects included 165 healthy schoolchildren aged 5 to 12 years.


METHODS
All subjects followed their habitual diet. Information on the main dietary habits of the study subjects was obtained by asking each child's parents to fill out a dietary questionnaire.


METHODS
Phytate and citrate concentration and excretion were measured in 2 urine samples (a spot sample and a 12-hour overnight sample) for each child. Furthermore, common urinary biochemical indicators of stone risk were measured in each sample.


RESULTS
The urinary phytate concentrations were low in this child population because of low consumption of dietary phytate. The urinary concentrations of phytate and citrate were low in 27.5% of these children.


CONCLUSIONS
Because both substances are important inhibitors of crystallization, these finding suggests that these children are at risk of crystallization. Moreover, their diets consisted of foods rich in animal protein, with insufficient consumption of vegetables, legumes, and fruits.
Laboratory of Renal Lithiasis Research, Faculty of Sciences, University Institute of Health Sciences Research (IUNICS-IdISPa), University of Balearic Islands, Palma de Mallorca, Spain. Electronic address: fgrases@uib.es.
Felix
F
Grases
Laboratory of Renal Lithiasis Research, Faculty of Sciences, University Institute of Health Sciences Research (IUNICS-IdISPa), University of Balearic Islands, Palma de Mallorca, Spain.
Concepcion
C
Saez-Torres
Laboratory of Renal Lithiasis Research, Faculty of Sciences, University Institute of Health Sciences Research (IUNICS-IdISPa), University of Balearic Islands, Palma de Mallorca, Spain.
Adrian
A
Rodriguez
Laboratory of Renal Lithiasis Research, Faculty of Sciences, University Institute of Health Sciences Research (IUNICS-IdISPa), University of Balearic Islands, Palma de Mallorca, Spain.
Antonia
A
Costa-Bauza
Department of Pediatric Nephrology, Son Espases Universitary Hospital, Palma de Mallorca, Spain.
Dolores
D
Rodrigo
Research Unit, Son Espases Universitary Hospital, Palma de Mallorca, Spain.
Guillem
G
Frontera
Laboratory of Renal Lithiasis Research, Faculty of Sciences, University Institute of Health Sciences Research (IUNICS-IdISPa), University of Balearic Islands, Palma de Mallorca, Spain.
Francisco
F
Berga
Kidney Stone Research Laboratory, Department of Chemistry, University of Cape Town, Cape Town, South Africa.
Saajidah
S
Fakier
D002648:Child; D002675:Child, Preschool; D019343:Citric Acid / Q000652:urine; D015331:Cohort Studies; D004032:Diet; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008297:Male; D053040:Nephrolithiasis / Q000175:diagnosis* / Q000652:urine; D015596:Nutrition Assessment; D010833:Phytic Acid / Q000652:urine*; D012307:Risk Factors; D013030:Spain; D011795:Surveys and Questionnaires
D019343:Citric Acid; D010833:Phytic Acid