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Biomedical subjects

Edgard E Delvin

Publications and source records attributed to Edgard E Delvin.

13 recordsLinked to original sources
PubMed2006

Gap analysis of pediatric reference intervals related to thyroid hormones and the growth hormone-insulin growth factor axis.

Efficacy of laboratory medicine in assisting attending physicians in their diagnostic and follow-up endeavors is intimately linked to an access to meaningful and reliable reference values. Pediatrics is particularly sensitive to this problem as the processes, associated with growth and development, are imposing rapid discontinuous changes on the physiology of the individuals. Some developmental stages are more critical than others. The neonatal and the pubertal periods, for which we lack reference ranges, are two such examples. Beyond biological considerations, we realize that, over the last 2 decades, technology has evolved, both at the analytical and reagent levels. This technological evolution inexorably leads to the need in redefining reference values. It is for this reason that a group of clinical and medical biochemists have joined their efforts in creating the Canadian Laboratory Initiative in Paediatric Reference (CALIPER) which objective is to define a pan-Canadian set of reference values from birth to late adolescence. To illustrate the need of such a venture, a brief gap analysis for biochemical variables related to the thyroid function, and the growth hormone-insulin-like growth factors axis follows.

Child↗
PubMed2006

Congenital hypothyroidism: from paracelsus to molecular diagnosis.

Endemic cretinism was noted in alpine Europe as early as the 13th century. However, it was only in 1848 that a commission, sponsored by the King of Sardinia, first formally demonstrated its link to goiter. An important landmark was the publication of a report in 1871 describing several cases of nongoitrous hypothyroidism that were clearly distinguished from the endemic form of the disease, for which the author suggested the designation of "sporadic cretinism." Classification of the hypothyroid status was for a long time solely based on clinical observation. In the second half of the 20th century, the use of radionuclides (iodine radioisotope and technetium pertechnetate) allowed a more precise diagnosis and taxonomy into thyroid dysgenesis and dyshormonogenesis. This brief review summarizes the progress that has been achieved during the last 40 years in diagnosing the multiple variants of congenital hypothyroidism (CH). It becomes evident that while accurate diagnosis for CH is readily available, its exact etiology requires a precise molecular investigation as different genes are implicated in the differentiation, migration and growth of the thyroid gland.

Congenital Hypothyroidism↗
PubMed2006

Adiponectin, adiposity, and insulin resistance in children and adolescents.

CONTEXT: Determinants of adiponectin and its association with insulin resistance (IR) are less well studied in youth than in adults. OBJECTIVES: The objective of the study was to describe, in youth, the age- and sex-specific distribution of adiponectin concentrations and the association with demographic, anthropometric, and lifestyle factors, parental diabetes, and markers of IR. DESIGN, SETTING, PARTICIPANTS: We studied 1632 French Canadian youth aged 9, 13, and 16 yr who participated in the Québec Child and Adolescent Health and Social Survey, a province-wide, school-based survey conducted in 1999. RESULTS: Boys had lower adiponectin concentrations than girls by 17% (P < 0.0001). At age 16 yr, mean adiponectin concentrations were 27.7% (boys, P < 0.0001) and 13.3% (girls, P < 0.0001) lower than at age 9 yr (p(interaction) = 0.009). Mean adiponectin decreased for every unit increase in body mass index (BMI) Z-score by 8.1% in boys and 11.2% in girls (P < 0.0001). Growth-related change in BMI explained half the age effect in boys and all the age effect in girls. Self-reported pubertal status, physical activity, smoking, and parental diabetes were not independently associated with adiponectin. Fasting insulin and homeostasis model assessment-IR were not associated with adiponectin concentration. However, the interaction of adiponectin and BMI Z-score was significant in a multiple regression model of fasting insulin. CONCLUSIONS: Male sex and changes in body fat may be major determinants of the decreasing adiponectin concentrations of growing youth, which are accompanied by a dissociation of adiponectin and markers of IR. The relationship between adiposity and markers of IR is attenuated in those with higher adiponectin concentrations, making adiponectin a potential intervention target or risk marker.

Adiponectin↗
PubMed2005

Distribution of LDL particle size in a population-based sample of children and adolescents and relationship with other cardiovascular risk factors.

BACKGROUND: Smaller, denser LDL particles are associated with an increased risk for cardiovascular diseases (CVD). In youths, data on the distribution of LDL particle size and on its association with other CVD risk factors are limited. METHODS: We determined LDL peak particle size by nondenaturing 2%-16% gradient gel electrophoresis in a representative sample of 2249 youths 9, 13, and 16 years of age who participated in a school-based survey conducted in 1999 in the province of Quebec, Canada. Standardized clinical measurements and fasting plasma lipid, glucose, and insulin concentrations were available. RESULTS: The LDL peak particle size distribution was gaussian. The 5th, 50th (median), and 95th percentiles by age and sex were 255.5-258.6, 262.1-263.2, and 268.1-269.5 A, respectively. The prevalence of the small, dense LDL phenotype (LDL peak particle size <or=255 A) was 10% in participants with insulin resistance syndrome (IRS), in contrast to 1% in those without IRS. In a multiple regression analysis, the association of LDL size with other CVD risk factors [apolipoprotein B, HDL-cholesterol (HDL-C), triglyceride (TG), and insulin concentrations, and body mass index] was strongest with TG and HDL-C concentrations: a 1 SD increase in log(e)-transformed TG concentration was associated with a 1.2 A reduction in LDL size, and a 1 SD increase in HDL-C was associated with a 1.1 A increase in LDL size. CONCLUSIONS: Although the small, dense LDL phenotype is less prevalent in youths than adults, its prevalence is clearly increased in childhood IRS. Metabolic correlates of LDL size are similar in youths and adults.

Adolescent↗
PubMed2005

Neonate capillary blood gas reference values.

OBJECTIVES: Because biological data are instrument-dependent and because technology has evolved over the last two decades, the published capillary blood reference values for blood gases, lactate, ionized calcium (iCa) and glucose may not reflect the present day situation. Hence, we report such values for healthy term neonates at 48 +/- 12 h of life. DESIGN AND METHODS: The Institution Ethics Review Board for Research on Human Subjects has accepted the protocol. Extra blood sample was obtained at the time heel-pricks were performed in the frame of the Quebec genetic screening program. One hundred twenty-six term neonates (39.6 +/- 1.2 weeks of gestation) were included in the study. pH, pO2, pCO2, lactate, ionized calcium and glucose were simultaneously measured with selective electrodes on the ABL 735 blood gas analyzer (Radiometer). RESULTS: All variables exhibited a Gaussian distribution. Since there was no gender effect, all data were pooled.

Blood Gas Analysis↗
PubMed2005

Oral vitamin A, E and D supplementation of pre-term newborns either breast-fed or formula-fed: a 3-month longitudinal study.

BACKGROUND: In contrast to the studies of vitamin A and E status in children, adolescents and adults, information on preterm infants is scarce. In the present investigation we examined the vitamin A, D and E status of pre-term infants at birth, and verified whether, at 1 and 3 months, breast or formula feeding affected the plasma concentration of those vitamins while being supplemented with Uvesterol ADEC. PATIENTS AND METHODS: In this prospective study, 2 groups of consecutively recruited preterm newborns fed either breast milk or formula received 3000 IU of vitamin A, 5 IU of vitamin E and 1000 IU of vitamin D daily. Vitamin A and E were measured by high performance liquid chromatography and spectrophotometry. 25-hydroxyvitamin D, a surrogate marker for vitamin D status, was measured by radioimmunoassay, and retinol binding-protein concentration was measured by immunonephelometry. RESULTS: At birth, formula-fed and breast-milk fed infants had similar plasma concentrations of vitamin A (0.75 +/- 0.20 and 0.64 +/- 0.21 micromol/L, ns), 25-hydroxyvitamin D (34.4 +/- 25.6 and 47.5 +/- 26.7 nmol/L, ns) and vitamin E (9.5 +/- 3.2 and 8.4 +/- 3.3 micromol/L, ns). Vitamins A and E, and retinol binding-protein concentrations steadily increased with time in both groups of infants without attaining, at 3 months, values considered normal in term infants and in young children. At 3 months of age, concentrations of 25-hydroxyvitamin D reached values comparable to those observed in term infants. CONCLUSION: Plasma concentrations of vitamins A and E and of retinol binding-protein steadily increased during the the study without reaching full repletion values. At the conclusion of the study, the type of nutrition did not affect plasma vitamin concentrations.

Adult↗
PubMed2004

C-reactive protein and features of the metabolic syndrome in a population-based sample of children and adolescents.

BACKGROUND: C-Reactive protein (CRP) is a risk marker for type 2 diabetes and cardiovascular diseases. In youth, limited data are available on the distribution of high-sensitivity CRP as well as on its association with components of the metabolic syndrome. METHODS: In 1999, we conducted a school-based survey of a representative sample of youths 9, 13, and 16 years of age in the province of Quebec, Canada. Standardized clinical measurements and fasting plasma lipid, glucose, insulin, and CRP concentrations were available for 2224 individuals. RESULTS: The distribution of CRP was positively skewed. The median and 95th percentile values by age and sex ranged from < 0.2 to 0.56 mg/L and from 2.72 to 6.28 mg/L, respectively. A total of 7.7% of 9-year-olds, 5.5% of 13-year-olds, and 12.8% of 16-year-olds had CRP concentrations > 3.0 mg/L, the threshold defining the adult high-risk category. We observed a strong relationship between CRP concentrations and both body mass index (BMI) and fasting insulin values. The association between CRP and insulin concentration was markedly attenuated after adjustment for BMI, whereas that between CRP and BMI remained unchanged after adjustment for insulin: a 1 SD increase in BMI was associated with a 52% increase in CRP concentration. An increased CRP concentration was independently associated with a worsening of the lipid profile, whereas the association between increased CRP values and high systolic blood pressure was no longer statistically significant after adjustment for BMI. CONCLUSIONS: The metabolic correlates of excess weight, including a state of low-grade systemic inflammation, are detectable early in life. Their health impact in adults remains to be fully examined.

Adolescent↗
PubMed2004

Reference intervals for free thyroxine, total triiodothyronine, thyrotropin and thyroglobulin for Quebec newborns, children and teenagers.

OBJECTIVE: Paediatric reference values, although essential for interpreting patients' results, are scarce. Moreover, they are often population- and instrument-dependent. We have measured free thyroxine (Free T(4)), total triiodothyronine (Total T(3)), thyroglobulin (Tg) and thyrotropin (TSH) in samples obtained from groups of newborns, children and adolescents. SUBJECTS AND METHODS: Blood samples collected from healthy children and teenagers (100 girls and 100 boys) of age groups ranging between 9-10, 11-14 and 15-17 years and selected randomly from a cohort representative of the Quebec population, were used. Samples from infants of age ranging between 1 day and 2 years (n = 99) were obtained from a hospital-based population with benign conditions unlikely to affect thyroid function. Variables were measured on the Access 2 immunosystem. RESULTS: Free T(4), Tg and TSH levels declined significantly with age. However, Total T(3) level presented a nonlinear variation with age, being lower in the first month of life.

Adolescent↗
PubMed2004

Twenty years later: a reevaluation of the contribution of plasma thyroglobulin to the diagnosis of thyroid dysgenesis in infants with congenital hypothyroidism.

BACKGROUND: The definition of the type of thyroid dysgenesis in congenital hypothyroidism (CH), ectopy, or athyreosis is important for monitoring patients and for genetic investigations. We have recently encountered infants who in spite of undetectable Technetium uptake on scintigraphy had biochemical results making athyreosis unlikely. OBJECTIVE: To reevaluate the utility of plasma thyroglobulin (Tg) in this clinical context using new sensitive Tg assays. SUBJECTS AND METHODS: Plasma Tg was retrospectively determined by two immunoassay systems on specimens obtained at diagnosis in 31 hypothyroid infants with thyroid dysgenesis. RESULTS: Scintigraphy led to the diagnosis of ectopy in 19 infants and of athyreosis in 12. Seven (58%) of the infants classified as athyreotic by scintigraphy had detectable plasma Tg (>0.2 microg/l), indicating that they had functional thyroid tissue. CONCLUSIONS: An undetectable plasma Tg should be documented to validate a scintigraphic diagnosis of athyreosis. Conversely, when plasma Tg is undetectable, scintigraphy could be avoided.

Female↗
PubMed2003

Distribution of fasting plasma insulin, free fatty acids, and glucose concentrations and of homeostasis model assessment of insulin resistance in a representative sample of Quebec children and adolescents.

BACKGROUND: Plasma fasting insulin and the homeostasis model assessment of insulin resistance (HOMA-IR) are markers of IR, which, at least in part, mediates the relation of obesity to increased cardiovascular risk. Increased free fatty acids (FFAs) may be involved in the pathogenesis of IR. Our objectives were to describe the distributions of fasting plasma insulin, glucose, and FFAs and HOMA-IR in youth and to assess the relationship between FFAs and markers of IR. METHODS: Fasting plasma insulin, glucose, and FFAs were measured in a representative sample of Quebec youth comprising 2244 individuals 9, 13, and 16 years of age. RESULTS: In all age and sex groups, glucose exhibited remarkably tight distributions (median CV, 7.1%) in contrast to insulin, HOMA-IR, and FFAs (median CVs, 52%, 54% and 45%, respectively). For every percentile examined, 9-year-olds had lower insulin concentrations and HOMA-IR values than 13- and 16-year-olds. We observed strong correlations between insulin concentrations and HOMA-IR values, as well as close similarity in their rankings of individuals. The mean concentrations of glucose were higher in our population than in other Caucasian pediatric populations. No positive correlations were detected between FFAs and markers of IR. CONCLUSIONS: We report some of the first data on the distributions of fasting plasma insulin, HOMA-IR, and FFAs from a representative sample of youth. HOMA-IR does not appear more informative than fasting insulin as a marker of IR. Our findings on higher mean glucose concentrations in this population require confirmation in other representative samples of youth to assess whether the North American distribution of glucose concentrations is shifting positively.

Adolescent↗
PubMed2003

The Québec Child and Adolescent Health and Social Survey: design and methods of a cardiovascular risk factor survey for youth.

BACKGROUND: Although atherosclerosis begins in childhood, there are no recent Canadian data on cardiovascular risk factors in provincially or nationally representative samples of youth. OBJECTIVE: To describe the design and methods of the 1999 Québec Child and Adolescent Health and Social Survey, which assessed the prevalence and distribution of risk factors in a representative sample of Québec youth. METHODS: School-based, multistage, cluster sampling survey of youth aged nine, 13 and 16 years. Measures included height, weight, subscapular and tricipital skinfolds, blood pressure (measured with the Dinamap), a fasting blood draw for assessment of lipoproteins and glucose, an age-adapted youth questionnaire on lifestyles and a parent questionnaire. RESULTS: One thousand two hundred sixty-seven, 1186 and 1160 subjects aged nine, 13 and 16 years, respectively, responded to the questionnaire and had height, weight, skinfold thickness and blood pressure measured (response proportions of 83%, 79% and 78% respectively); 783, 818 and 874 subjects of the same age agreed to the blood draw (response proportions of 52%, 55% and 59%, respectively). Comparisons of characteristics of participants and nonparticipants in the blood draw showed few differences. The mean relative difference between lipoprotein and glucose values obtained at the study laboratory and a reference method varied from -0.3% to 6.1%. Design effects for means and proportions varied from 1.0 to 1.8. CONCLUSION: Despite its complexity, this survey was able to achieve a high level of precision for multiple measures. It will provide the most complete data on cardiovascular risk factors ever collected among children and adolescents in Canada.

Adolescent↗