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Biomedical subjects

P Bourdoux

Publications and source records attributed to P Bourdoux.

At least 19 recordsLinked to original sources
PubMed1998

Autonomy in endemic goiter.

The occurrence of hyperthyroidism in many individuals after introduction of iodine prophylaxis in endemic goiter areas can have dramatic consequences for the affected individuals. It indicates that in such individuals the increase of serum thyroid hormone level in response to iodine supplementation does not exert its normal negative feedback on thyroid activity, ie, that in such individuals some thyroid tissue has become autonomous. In this short review we summarize what is known about the possible mechanisms, cause, diagnosis, and consequences of thyroid autonomy.

Goiter, Endemic↗
PubMed1998

Iodine-induced hyperthyroidism: occurrence and epidemiology.

We have critically reviewed the available information on iodine-induced hyperthyroidism (IIH) from published sources and other reports as well as the experience of the authors in Tasmania, Zaire, Zimbabwe, and Brazil. Administration of iodine in almost any chemical form may induce an episode of thyrotoxicosis (IIH). This has been observed in epidemic incidence in several countries when iodine has been given as prophylaxis in a variety of vehicles, but the attack rate as recorded has been low. IIH is most commonly encountered in older persons with long standing nodular goiter and in regions of chronic iodine deficiency, but instances in the young have been recorded. It customarily occurs after an incremental rise in mean iodine intake in the course of programs for the prevention of iodine deficiency, or when iodine-containing drugs such as radiocontrast media or amiodarone are administered. The biological basis for IIH appears most often to be mutational events in thyroid cells that lead to autonomy of function. When the mass of cells with such an event becomes sufficient and iodine supply is increased, the subject may become thyrotoxic. These changes may occur in localized foci within the gland or in the process of nodule formation. IIH may also occur with an increase in iodine intake in those whose hyperthyroidism (Graves' disease) is not expressed because of iodine deficiency. The risks of IIH are principally to the elderly who may have heart disease, and to those who live in regions where there is limited access to medical care. More information is needed on the long-term health impact of IIH or "subclinical" IIH, especially in the course of prophylaxis programs with iodized salt or iodinated oil in regions where access to health care is limited.

Age Distribution↗
PubMed1998

Influence of dietary habits on thyroid status of a nomadic people, the Bororo shepherds, roaming a central African region affected by severe iodine deficiency.

OBJECTIVE: In contrast with the endemic goiter reported in several African countries, the nomadic Bororos of the Central African Republic have an unexpectedly low prevalence of goiter. This study was conducted to elucidate this puzzling observation. DESIGN: Thyroid function and iodine and thiocyanate intakes were evaluated in Bororos and inhabitants of the same area and compared with an Italian population. RESULTS: Urinary iodine concentrations indicated moderate iodine deficiency in the rural people and the Bororos. In the latter, no individual with clinical hypothyroidism was observed. Compared with the reference population, the Bororos had slightly lower thyroxine (T4) and free thyroxine (FT4), slightly increased tri-iodothyronine (T3) and T3/T4 ratio, slightly higher TSH, normal serum thyroglobulin, a prevalence of goiter of 17.1% and a higher urinary thiocyanate. The rural people showed striking differences: lower T4 and FT4, increased T3/T4 ratio, markedly increased TSH and thyroglobulin, a prevalence of goiter of 76.9% and a high urinary thiocyanate, indicating frequent consumption of cassava. A dietary survey indicated that the Bororos ingest large amounts of milk and related products but infrequently eat cassava. CONCLUSION: A minute difference in iodine deficiency between two populations induces totally different patterns of goiter and thyroid function. The reason for such a contrast probably involves differences in diet.

Adolescent↗
PubMed1997

Fairly elevated incidence of goiter with marginally low urinary iodine in adolescents living in the north-western part of Tunisia.

In order to study the etiology of endemic goiter in the north-western part of Tunisia, we examined 93 adolescents of this region. We measured urinary iodine concentrations, serum total thyroxine, total triiodothyronine, thyrotropin, thyroglobulin and antithyrogobulin antibody concentrations. The adolescents were questioned about their alimentary habits, the origin of their drinking water and the presence of known goiter(s) in their family. Among these adolescents, 49.5% of them had a goiter. Urinary iodine concentrations showed mild iodine deficiency. The serum determinations gave results within the reference ranges, without any significative differences between adolescents, with or without goiter. We found two risk factors: the age of adolescents, and the presence of a known goiter in the family. These results suggest that the actual prevention may not be adequate, or most likely that goitrogenic factors are to be looked for, especially in drinking water, since the majority of these adolescents drink no controlled water.

Adolescent↗
PubMed1997

[Iodine deficiency in the Cirque of Salazie (Reunion Island). Analysis of nutritional causes and study of their consequences].

Randomized subjects (n = 294), (35 young children, 6-30 months old--91 children 8.6 +/- 0.7 years, 116 teenagers 13.2 +/- 1.9 y--52 young women 28.5 +/- 6.1 y) leaving in a mountainous area of Reunion Island (Cirque de Salazie) were evaluated according to the following: a questionnaire related to food intake, cervical palpation for thyroid size evaluation and collections of urine and foods (natural and mineral water, breast and commercial milk and salt) for iodine measurement. Neonatal TSH of 308 new borns in Salazie were compared to TSH of 300 new-borns of Lille (France). The prevalence of goiter increases with age (0% in young children, 12.1% in children, 23.3% in teenagers, 38.4% in women) whereas median urinary iodine (microgram/dl) decreases in the same groups (12-7.8-5.6-4.2). The intake of milk and dairy products significantly decreases from children to adults. Neonatal TSH values are significantly higher in Salazie than in Lille (p < 0.005). Natural and mineral water, breast milk and salt contain little iodine. In conclusion iodine deficiency is present in this area of Reunion Island with a significant increment of neonatal TSH values.

Adolescent↗
PubMed1996

Human thyroglobulin reference material (CRM 457). 1st Part: Assessment of homogeneity, stability and immunoreactivity.

This paper describes the assessment of the homogeneity and stability of a purified and lyophilized human thyroglobulin (Tg), and characterizes its immunoreactivity. The purified and lyophilized Tg is intended to be used as a primary reference material to establish calibration of working serum based reference material. The programme involved the participation of 15 European laboratories and one laboratory from the United States. The homogeneity of the content of the ampoules was considered acceptable (< 9%). The stability was tested by accelerated temperature degradation showing predicted annual relative losses of 0.01% at -70 degrees C and 1.04% at -20 degrees C. The immunoreactivity of the Tg material as measured in different laboratories varied mostly according to the method used rather than the laboratory. The interlaboratory variability showed that the two commercial methods used in several laboratories (kit 1 and 2) had an interlaboratory variation (CV) of 15.9% (N = 5) and 7.1% (N = 3), respectively, whereas the total interlaboratory CV was 64.3% (N = 18). The immunoreactive Tg had dilution curves parallel with other Tg calibrators (those of the methods). Dilution curves of the Tg material after storage at various temperatures and time were parallel in both RIA and IRMA. In conclusion, we have prepared a Tg reference material which in extensive studies in several participating laboratories has demonstrated a sufficient homogeneity and stability as well as dilution curves parallel to the calibrators of all the immunoassays tested in the study. This reference material is considered the first step towards decreasing the interlaboratory variability between Tg immunoassays.

Drug Stability↗
PubMed1996

Human thyroglobulin reference material (CRM 457). 2nd Part: Physicochemical characterization and certification.

This report describes the characterization of a purified human thyroglobulin (Tg) reference material, and details the procedures used in its certification. The purified Tg is intended to be used as a primary reference material to establish calibration of working serum based reference material for immunoassay procedures. The programme involved the participation of 15 European laboratories and one laboratory from the United States. The physicochemical characterization showed by polyacrylamide gel electrophoresis and immunoblotting that the purified Tg had for the major part the expected molecular size of 660 kDa with traces of lower molecular forms. The amino acid composition was close to that demonstrated for the cDNA and the content of iodine was in keeping with a moderately to highly iodinated Tg. The mass concentration in reference material RM 457 is certified to be (0.324 +/- 0.018) g/L on the basis of protein determined by the Lowry method and supported by nitrogen determination, absorbance measurement, and amino acid analysis. This reference material is considered the first step towards decreasing the interlaboratory variability between Tg methods of measurement.

Amino Acids↗
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↗
PubMed1995

[Thyroid and AIDS].

Two types of thyroid biochemical abnormalities (TBA) are observed in AIDS. The unspecific TBA are similar to TBA reported in the Euthyroid Sick Syndrome. An increased serum TBG of unknown origin and a decreased circulating rT3 are the most specific TBA of AIDS. The latter abnormality may be in relation with an elevated level of TNF. The frequency of serum antithyroid antibodies seems higher than in control groups. Opportunistic infections of the thyroid gland or destruction of the thyroid by Kaposi's sarcoma are also reported in AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Blood spot follicle-stimulating hormone during early postnatal life in normal girls and Turner's syndrome.

Although FSH has previously been found to be elevated during infancy in agonadal subjects, it is not known whether perinatal FSH levels are also increased. Neonatal blood spot FSH levels were studied retrospectively in nine full term girls born with Turner's syndrome and compared with presumably normal full term girls born the same week. FSH was measured using a highly specific immunoradiometric assay adapted to blood spots collected at the time of systematic neonatal screening. On day 5-6 after birth, FSH was undetectable (< 1 IU/L) or low (1-4.4 IU/L) in normal girls. Among the nine patients with Turner's syndrome, five had FSH levels below 3 IU/L, and four showed slightly elevated levels, ranging from 4.3-10.9 IU/L. These differences in FSH secretion were not related to differences in karyotype. Among five patients studied longitudinally during the first 6 weeks of life, three showed increases in FSH levels to 14.9-15.9 IU/L during the second week of life. However, this increase was comparable to that seen in some normal girls sampled on a second occasion during the first weeks after birth. One patient with Turner's syndrome still had low FSH (2.5 IU/L) on day 23, but showed some increase to 8.5 IU/L on day 30. We conclude that 1) in Turner patients, perinatal changes in FSH secretion are similar to those in normal girls, although there is already a lack of feedback control by gonadal hormones on the hypothalamo-pituitary axis; and 2) the FSH assay cannot be used for neonatal screening of Turner's syndrome.

Female↗
PubMed1993

The epidemiology of iodine-deficiency disorders in relation to goitrogenic factors and thyroid-stimulating-hormone regulation.

In children aged 5-7 y from goiter-endemic areas in Ubangi, Zaire, and Ntcheu, Malawi, mean serum thyroxin (T4) concentrations were 53 +/- 49 vs 81 +/- 33 nmol/L (P < 0.05), and thyroid-stimulating hormone (TSH) values were 24.3 +/- 9.6 vs 4.5 +/- 3.3 mU/L respectively (P < 0.01); mean urinary iodine concentrations were 0.14 +/- 0.02 vs 0.09 +/- 0.02 mumol/L, and mean thiocyanate concentrations were 0.33 +/- 0.05 vs 0.17 +/- 0.05 nmol/L, respectively (P < 0.05). Mean serum selenium concentrations were 0.343 +/- 0.176 mumol/L in Ubangi and 0.437 +/- 0.178 mumol/L in Ntcheu (P < 0.05). In two groups of 11 adolescent girls from Ubangi, the mean values for excretion of urinary iodine were 1.31 +/- 0.14 and 0.58 +/- 0.17 mumol/L (P < 0.05) after a meal of cassava or a control meal of rice, respectively. In euthyroid subjects from Ubangi, mean serum TSH for a given serum T4 was approximately twice as high for children aged < 15 y than for those aged 16-25 y. The high frequency of myxedematous cretins observed in Ubangi very probably result from both severe iodine and selenium deficiency together with thiocyanate overload.

Adolescent↗
PubMed1992

Efficacy of low oral doses of iodized oil in the control of iodine deficiency in Zaire.

BACKGROUND: About one billion people worldwide are at risk for iodine deficiency. Despite existing programs of prophylaxis, the prevention of iodine deficiency is still a challenge throughout the developing world. We studied the efficacy of low doses of iodized oil in an area of severe iodine deficiency in Zaire. METHODS: Seventy-five subjects with visible goiter were randomly assigned to receive a single oral dose of placebo or either 0.1 or 0.25 ml of iodized oil, corresponding to 0, 47, and 118 mg of iodine, respectively. The mean ages of the subjects in the three groups were 23, 22, and 22 years, respectively, and the ratios of males to females were 0.25, 0.32, and 0.19. Efficacy was assessed by evaluating goiter size and measuring urinary iodine and serum thyroid hormone concentrations for 12 months. RESULTS: Goiter size decreased in most of the subjects who received either dose of iodized oil. Their urinary iodine concentrations were normal for six to nine months and their serum thyroxine and thyrotropin concentrations were nearly all normal throughout the study period. There were no side effects, even in subjects whose serum thyroxine concentrations had initially been low. In the placebo group, neither goiter size nor any of the biochemical values changed. CONCLUSIONS: The oral administration of a single small dose of iodized oil is capable of correcting iodine deficiency for about a year. This method of supplementation is likely to be more effective, efficient, and acceptable than the administration of either intramuscular or large oral doses of iodized oil.

Administration, Oral↗
PubMed1992

Risk of osteoporosis in men with chronic bronchitis.

Theoretically, patients with chronic bronchitis are at risk for osteoporosis. Bone metabolism was assessed in 44 male chronic bronchitics treated with oral prednisolone (C+; n = 19) or with bronchodilatory drugs alone (C-; n = 25). In both groups, serum osteocalcin was lower (p less than 0.001) than in age- and sex-matched controls (mean (ng/ml) C+ 1.0, C- 1.9, controls 4.2), while testosterone was at the lower limit of the reference range. Low trabecular bone mineral density (BMD) was noted in the C- group (median Z score -1.0), but both cortical and trabecular BMD were depressed in the C+ group (-1.0 and -1.4, respectively). In conclusion, chronic bronchitics treated with corticosteroids, even at low doses, are at risk for osteoporosis. In both groups, additional factors such as hypogonadism might be responsible for low BMD and low osteocalcin levels. A decrease in bone formation is a possible mechanism of action.

Adrenal Cortex Hormones↗
PubMed1992

Partial reversibility during late postpartum of thyroid abnormalities associated with pregnancy.

The aim of the present work was to assess during late postpartum the reversibility of thyroidal alterations associated with pregnancy. Thyroid function was reinvestigated 6 months after delivery in 100 randomly selected healthy women and thyroid volume was reevaluated 12 months after delivery in 10 other selected women. The subjects had previously been carefully followed during gestation as they were included in a prospective cohort investigation of the regulation of the thyroid during pregnancy, in an area with a limited dietary iodine intake (less than 100 micrograms/day in 85% of the women). Six months after delivery, an overall normalization of thyroid function was observed. However, an increase in the T3/T4 ratio, which was present in half the cases at delivery, was still evident 6 months postpartum, suggesting the persistence of relative iodine deficiency, probably prolonged in some women through breast-feeding. Furthermore, serum thyroglobulin levels, which were increased in half the women at delivery, remained abnormally high in 40% of them 6 months later. Twelve months after delivery thyroid volume, which had increased in average by 54% during pregnancy, had not reverted to the values found during early gestation. Moreover a goiter was still evident in 2/4 cases in whom it had developed during pregnancy. In conclusion, the present study indicates that pregnancy may constitute a prolonged stimulus for the thyroid and shows for the first time that the alterations associated with gestation are not limited to the period of pregnancy, being only partially reversible during late postpartum. In conditions with a limited iodine intake, pregnancy constitutes a risk for the maternal thyroid: goitrogenesis does occur and may be maintained after delivery. The glandular stress of pregnancy may therefore provide a clue to understanding the high prevalence of thyroid disorders in women. The present study provides additional arguments to suggest that iodine supply be increased during pregnancy but also after parturition, in particular in breast-feeding mothers.

Cohort Studies↗
PubMed1992

Maternal and neonatal thyroid function at birth in an area of marginally low iodine intake.

Thyroid function was evaluated in cord serum of healthy full-term newborns and compared to that of mothers immediately after parturition. The study was carried out in an area without overt iodine deficiency, but with a marginal iodine supply (less than 100 micrograms/day in 80% of women). The aim of the study was to delineate the interrelationships between the thyroid statuses of mother and child at birth. Maternal thyroid function was characterized at delivery by relative hypothyroxinemia; increased T3/T4 ratios, indicating preferential T3 secretion; slightly increased TSH levels within the normal range in 97% of women; increased serum thyroglobulin (TG) values, which were above normal in 60% of women; and also goiter formation in almost 10% of women. The findings indicated glandular stimulation and confirmed our earlier reports that pregnancy constitutes a stress for the maternal thyroid economy, enhanced by the limited availability of iodine in the diet. By contrast, newborns showed a strikingly distinct pattern: there was no relative hypothyroxinemia and free T4 levels were significantly higher than in the respective mothers (19.4 vs. 14.7 pmol/L; P less than 0.001). In spite of these differences, however, mean neonatal TSH and TG levels were significantly higher than maternal values, respectively 6.0 vs. 1.9 mU/L for TSH (P less than 0.001) and 70 vs. 40 micrograms/L for TG (P less than 0.001). Furthermore, neonatal TG and TSH levels increased in parallel and were highly correlated with maternal data, suggesting a regulatory link between both thyroid economies. The results suggested that the common regulatory link is the limited availability of the iodine supply. In conclusion, the present study demonstrates that even in conditions with a marginally low iodine intake, pregnancy constitutes a stimulus for both the maternal and newborn thyroids. Changes in both groups are associated and the abnormalities in TSH and TG are amplified in the newborns. The TSH and TG alterations at birth in full-term healthy newborns, associated with similar alterations in maternal thyroid function, provide evidence for a common stimulatory factor, relative iodine deficiency. The data emphasize the hypersensitivity of neonatal thyroid function to marginal iodine deficiency and point to the need to increase the iodine supply in groups at risk, such as women during pregnancy, and also newborns in the perinatal period.

Cohort Studies↗