The determination of urinary electrolytes is helpful in the
diagnosis of children with certain diseases such as dyselectrolytemia
or metabolic acid–base imbalance of unknown origin
. Diurnal variations of urinary solute excretion have been
reported in children, but few data dealing with chronobiological
aspects are available [2–7]. We found worth studying the
circadian rhythm of urinary variables with the aim to establish
circadian reference values in prepubertal boys. We therefore
examined the 24-h urinary excretion of a set of routinely
determined variables: electrolytes (calcium, magnesium, and
phosphorus), urea, and creatinine in urine of voluntary healthy
Nine healthy prepubertal (Tanner stage I) boys aged 10.8±0.11
years, attending the same junior school and the same classroom,
were enrolled into the study (Table 1). All had normal growth
parameters and close weight, height, and bodymass index, had no
known medical illnesses or endocrine dysfunction and were not
receivingmedications. The children of this study were comparable
and had roughly the same synchronization (time to bed and time
awake), the same type of diet (quality and quantity) and mainly
drank water with one to two sodas per day. Parental consent and
children's assent were obtained before entry into the study. The
study was approved by the Review Board of the Institute and
performed in agreement with the Standards and Ethics in
Biological Rhythm Research .
The subjects were admitted on a weekend during spring, after
the class for 24 h at the same location (at home of the first author)
in Paris, France. Subjects were required to be in bed with the
roomlights turned off from21:00 h±30 min to 07:00 h±30 min, a
schedule close to their usual synchronisation. Meals were provided
at 07:30 h±30 min, 12:00 h±30 min and 20:00 h±30 min.
To standardize the experimental conditions in regards to posture
and physical activity, children rested about 30min during daytime
before each sampling.
Total urine voidings were collected during nine consecutive 3-h periods.
Urine sampleswere stored at −20 °C until processed.
Biochemical determinations of urinary solutes have been described previously .
The assays for each variable were done in a single series to avoid analytical variations between assays.
Calcium was determined using a cresolphthalein method (Biomérieux kit, France).
Magnesium was determined using an EGTA-calmagite manual method (Biomérieux kit,
Phosphorus was determined using an ammonium molybdate–iron sulphate manual method (Biomérieux kit, France).
Urea was determined using an urease method (Beckman, model Astra 4).
Creatinine was determined using the Jaffé method (kinetic, Beckman Astra).
The urinary solutes (calcium, magnesium, phosphorus, and urea) were measured in relation to creatinine (ratio).
- 迷你Lv 71 decade agoFavorite Answer
9個健康的青春期（唐納第一階段）的男孩年齡 10.8 ± 0.11
喝的水與 1時 59分每天汽水。父母的同意，兒童的同意之前，獲得進入研究。那個研究批准了審查委員會的研究所和演出協議的標準和倫理生物節律研究。
roomlights關閉 from21：00 ħ ± 30分鐘至07:00 ħ ± 30分鐘，1
在07:30 ħ ± 30分鐘，12:00 ħ ± 30分和20時 00 ħ ± 30分鐘。
共收集尿液voidings在連續 9 3 - H的時期。