Variability of creatinine excretion of normal, phenylketonuric and galactosemic children, and children treated with anticonvulsant drugs

Lewis, Jane S.; Bunker, Mary Louise; Getts, Sue S.; Essien, Ruth

doi:10.1093/ajcn/28.4.310

Cited by 8 publications

(2 citation statements)

References 16 publications

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“…Thus, a pos sible variation in renal tubular function cannot be cor rected for by creatinine measurement. In addition, our study was in agreement with findings of others in which creatinine excretion varied considerably, with several fold changes in the rate of creatinine excretion over 24 h [34,[37][38][39], This finding could not be attributed to the creatinine assay, since the interassay variation was only 2.5% in our laboratory. Thus, if urinary protein excre tion was related to creatinine, the total 24-hour excretion was overestimated for night samples and underestimated for day samples [34], Finally, we found a significant increase in creatinine excretion with age (p < 0.001), which blunted the pubertal u-GH excretion peak.…”

Section: Discussionsupporting

confidence: 93%

Urinary Growth Hormone Excretion in 657 Healthy Children and Adults: Normal Values, Inter- and Intraindividual Variations

Main

Philips

Jørgensen³

et al. 1991

Horm Res

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Urinary growth hormone (u-GH) excretion was measured in 547 healthy children and 110 adults by ELISA with a detection limit of 1.1 ng/l u-GH after prior concentration of the urine samples (20- to 30-fold). u-GH excretion values were significantly dependent on the pubertal stage (p < 0.0001) with maximum values in Tanner stage 3 for girls and 4 for boys. This corresponded to a peak in u-GH excretion between 11.5–14.5 years in girls and 12.5–16 years in boys. Additionally, u-GH excretion in adults was significantly higher than in prepubertal children (p < 0.001). The day/night ratio of u-GH excretion (pg/h) was significantly higher in females than in males (p < 0.01). In Tanner stages 1–4, u-GH excretion during the day was lower than that at night, whereas the opposite was true in late puberty and in adult women. The interindividual variation of u-GH excretion within the same Tanner stage was considerable and approximately double the intraindividual variation. The day-to-day variation could be further reduced by collection of three consecutive urine samples. The variations were larger if night samples instead of 24-hour samples were considered. The expression of u-GH excretion in nanograms per gram creatinine did not diminish the observed variation and blunted the pubertal increase in u-GH excretion. In conclusion, (1) u-GH excretion depends significantly on age, sex and pubertal maturation as does the day/night ratio of u-GH excretion. (2) The intraindividual variation in u-GH excretion is considerable. In contrast, the interindividual variation is only half as large and can be further reduced by consecutive samples. (3) It is of no advantage to relate u-GH excretion to creatinine output. Thus, we recommend that reference intervals for u-GH excretion be expressed in nano- or picograms per period. They should be based on a large number of healthy volunteers of both sexes and on either 24-hour or on several overnight urine collections.

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Section: Discussionsupporting

confidence: 93%

Urinary Growth Hormone Excretion in 657 Healthy Children and Adults: Normal Values, Inter- and Intraindividual Variations

Main

Philips

Jørgensen³

et al. 1991

Horm Res

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“…This increase is more rapid in small children compared with adolescents, and in boys compared with girls, and falsely attenuates the age-related increase in bone marker excretion. Circadian variation in urinary creatinine, with higher values during the day, may influence results of 24 h specimens versus morning specimens [32]. In girls, creatinine excretion varies during the menstrual cycle.…”

Section: Methodologic Issuesmentioning

confidence: 99%

Biochemical Measurements of Bone Turnover in Children and Adolescents

Szulc

Seeman

Delmas

2000

Osteoporosis International

337

243

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Biochemical measurements of bone turnover are helpful in the study of the pathophysiology of skeletal metabolism and growth. However, interpretation of their results is difficult because they depend on age, pubertal stage, growth velocity, mineral accrual, hormonal regulation, nutritional status, circadian variation, day-to-day variation, method of expression of results of urinary markers, specificity for bone tissue, sensitivity and specificity of assays. Three markers of bone formation have been described including their bone specificity and age-related changes: osteocalcin, alkaline phosphatase and its skeletal isoenzyme, procollagen I extension peptides. Bone resorption markers (hydroxyproline; deoxypyridinoline; pyridinoline; peptides containing these crosslinks such as N-telopeptide to helix in urine (NTX), C-telopeptide-1 to helix in serum (ICTP) and C-telopeptide-2 in urine and serum (CTX); tartrate-resistant acid phosphatase; hydroxylysine and its glycosides) are described with special attention to methodologic issues, mainly ways of expression of their results. Changes of bone turnover during growth are described during four periods: infancy, prepubertal period, puberty and the postpubertal period. Pubertal changes of bone markers are described with special attention to gender differences and hormonal mechanisms of the growth spurt which determine differences related to the pubertal stage. Disturbances of bone turnover in four conditions are described to illustrate the impact of such diseases on growth and formation of peak bone mass: prematurity, malnutrition, growth hormone deficiency and corticosteroid-treated bronchial asthma. Available data suggest biochemical markers of bone remodeling may be useful in the clinical investigation of bone turnover in children in health and disease. However, their use in everyday clinical practice is not advised at present.

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Probabilistic prediction of exposures to arsenic contaminated residential soil

Lee

Kissel

1995

Environ Geochem Health

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Probabilistic modelling using Monte Carlo simulation has been proposed as a more scientifically valid method of estimating soil contaminant exposures than conservative deterministic methods currently used by regulatory agencies. A retrospective application of probabilistic modelling to an exposure scenario involving arsenic-contaminated residential soil near the former ASARCO smelter near Tacoma, Washington is presented. The population of interest is children, aged 2-6 years, living within one-half mile (0.3 km) of the smelter site. Models that predict urinary arsenic levels based on unintentional soil ingestion and inhalation exposure pathways are used. Distributions of exposure variables are based on site-specific data and previous exposure studies. Simulated urinary arsenic levels are compared with data from two biomonitoring studies performed during the late 1980s. Arsenic distributions produced by simulation and biomonitoring are significantly different, and likely contributors to this difference are discussed. However the probabilistic model provides closer estimations of urinary arsenic levels than conservative deterministic models similar to those used by regulatory agencies, and provides useful information regarding parameter uncertainty. Soil ingestion rate was a driving variable in the probabilistic models. Further quantification of soil ingestion rates is warranted.

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Variability of creatinine excretion of normal, phenylketonuric and galactosemic children, and children treated with anticonvulsant drugs

Cited by 8 publications

References 16 publications

Urinary Growth Hormone Excretion in 657 Healthy Children and Adults: Normal Values, Inter- and Intraindividual Variations

Urinary Growth Hormone Excretion in 657 Healthy Children and Adults: Normal Values, Inter- and Intraindividual Variations

Biochemical Measurements of Bone Turnover in Children and Adolescents

Probabilistic prediction of exposures to arsenic contaminated residential soil

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