Biomedical subjects

H V Van Thi

Publications and source records attributed to H V Van Thi.

4 recordsLinked to original sources

PubMed2003

Quantification of urinary iodine: a need for revised thresholds.

OBJECTIVE: To compare different possibilities of reporting the iodine supply in the same urine samples. Indeed, in field studies, urinary iodine concentration (I/L: micro g I/L, micro mol I/L, I/creatinine: micro g I/g creatanine, micro mol I/mol creatinine) is more readily available than excretion (I/24h micro g I/24 h, micro mol I/24h). However, confusion exists regarding the comparability of iodine supply based upon I/L, I/creatinine and I/24h, which for decades have been regarded as biochemically equivalent. DESIGN: We compared I/24h, I/L and I/creatinine in accurate 24 h collections of urine and I/L and I/creatinine in 47 spot urine samples. PATIENTS: A total of 13 subjects (Bern n=7, Brussels n=6) collected a total of 110 precise 24 h urine collections (Bern n=63, Brussels n=47). The subjects from Brussels also took a spot sample at the beginning of each 24 h collection. RESULTS: Iodine supply in both places was mildly deficient according to the criteria of WHO; all but one collection indicated an intake of >0.39 micro mol I/24h (>50 micro g I/24h). The same data presented as I/creatinine (or I/L) indicated an iodine intake of <0.39 (<50 micro g I/24h) in 5% (24%) of the samples in Bern and 23% (57%) in Brussels. Similar findings were observed for 47 spot samples. Whatever the cut-off selected, I/creatinine and I/L were systematically lower than I/24h (P<0.0002). Creatinine showed smaller CV than volume but did not perform better in defining iodine intake. CONCLUSION: Considering I/24h as a reference, both I/creatinine and I/L clearly underestimate the iodine intake in subjects with adequate proteoenergetic intake. The significant deviations observed illustrate the urgent need for establishing separate ranges for I/24h, I/creatinine and I/L. In population studies, these deviations might even be larger.

Adult↗

PubMed1995

The use of sugar as a vehicle for iodine fortification in endemic iodine deficiency.

The use of sugar as a vehicle for iodine supplementation was explored in a study of iodine deficiency in the Sudan. A survey of sugar consumption was conducted and established a widespread and uniform intake of sugar in all ages with no differences among socio-economic groups. The daily intake among adults varied from 48 g to 78 g as examined in five different geographical areas in the country. Iodinated sugar was produced by addition to sugar solution prior to crystallisation in an evapocrystallizer or sprayed on the conveyor of cured sugar before it entered the dryers. Subsequently, the iodinated sugar was given to members of 18 and 60 families in a mildly (urinary iodine < 5.1 micrograms/dl) and moderately (urinary iodine < 3 micrograms/dl) iodine deficient areas, respectively, over a 1-month and a 6-month period, respectively. In both tests, improvements were recorded, i.e. the rates of goitre decreased, urinary iodine levels increased significantly (from 5.1 to 14.4 micrograms/dl and from 3 to 9.8 micrograms/dl, respectively) and thyroid hormones values rose. No side effects were noted. The results indicate that fortification of sugar with iodine may serve as a new alternative approach in attempts to eradicate iodine deficiency related disorders in endemic areas.

Adolescent↗

PubMed1991

Superiority of thyrotropin to thyroxine as a tool in the screening for congenital hypothyroidism by the filter paper spot technique.

The effects of storage on the assessment of thyroxine (T4) and thyrotropin (TSH) were evaluated in blood spots collected on filter paper according to the methods commonly used in screening for congenital hypothyroidism. Comparisons were made with serum values obtained simultaneously in the same subjects. In samples stored at room temperature a clear-cut decrease in T4 was observed after 24 hours while TSH was stable for at least 15 days. Spot samples collected in an area of severe endemic goiter in Africa and analyzed in Brussels displayed a systematic decrease in T4 (up to 133 nmol/l) while TSH was fairly stable. Spot samples collected in Belgium were stored at -18 degrees C and were reassayed after 1 year; they did not show any significant change in TSH but a systematic decrease in T4. We conclude that spot TSH is the tool of choice in screening for congenital hypothyroidism particularly in developing countries and that spot T4 should not be used for field studies or under any circumstances in which assays cannot be performed very soon after blood collection.

Blood Preservation↗

PubMed1988

Increased recall rate at screening for congenital hypothyroidism in breast fed infants born to iodine overloaded mothers.

Skin disinfection with povidine-iodine (PVP-I) is widely used in obstetrics. We evaluated the influence of PVP-I in mothers at delivery on the serum thyroid stimulating hormone concentrations of their infants at the time of screening for congenital hypothyroidism. The study covered 4745 infants who were either breast fed (3659, 77%) or bottle fed (1086, 23%); 3086 (65%) of them were born to mothers with no iodine overload (controls) and 1659 (35%) to mothers with iodine overload. Compared with the control group, the breast and bottle fed infants born to mothers with iodide overload had a shift of neonatal thyroid stimulating hormone concentration towards high values. The shift was maximal in the breast fed infants with a 25 to 30 fold increase in the recall rate at screening for congenital hypothyroidism (serum thyroid stimulating hormone greater than 50 mU/l) while in the bottle fed infants, the recall rate was barely modified. In conclusion, the use of PVP-I in mothers at delivery induces a transient impairment of thyroid function in their infants, especially if breast fed. This situation is detrimental to screening for congenital hypothyroidism. Consequently PVP-I is not recommended in obstetrics.

Breast Feeding↗