Iron deficiency predicts poor maternal thyroid status during pregnancy

CONTEXT

Pregnant women are often iron deficient, and iron deficiency has adverse effects on thyroid metabolism. Impaired maternal thyroid function during pregnancy may cause neurodevelopmental delays in the offspring.

OBJECTIVE

Our objective was to investigate whether maternal iron status is a determinant of TSH and/or total T(4) (TT4) concentrations during pregnancy.

DESIGN AND OUTCOME MEASURES

In a representative national sample of Swiss pregnant women (n = 365) in the second and third trimester, samples of urine and blood were collected, and data on maternal characteristics and supplement use were recorded. Concentrations of TSH, TT4, hemoglobin, mean corpuscular volume, serum ferritin, transferrin receptor, and urinary iodine were measured. Body iron stores were calculated and stepwise regressions performed to look for associations.

RESULTS

Median urinary iodine was 139 mug/liter (range 30-433). In the third trimester, nearly 40% of women had negative body iron stores, 16% had a TT4 less than 100 nmol/liter, and 6% had a TSH more than 4.0 mU/liter. Compared with the women with positive body iron stores, the relative risk of a TT4 less than 100 nmol/liter in the group with negative body iron stores was 7.8 (95% confidence interval 4.1; 14.9). Of the 12 women with TSH more than 4.0 mU/liter, 10 had negative body iron stores. Serum ferritin, transferrin receptor, and body iron stores were highly significant predictors of TSH (standardized beta: -0.506, 0.602, and -0.589, respectively; all P < 0.0001) and TT4 (standardized beta: 0.679, -0.589, and 0.659, respectively; all P < 0.0001).

CONCLUSION

Poor maternal iron status predicts both higher TSH and lower TT4 concentrations during pregnancy in an area of borderline iodine deficiency.

Determining median urinary iodine concentration that indicates adequate iodine intake at population level

OBJECTIVE

Urinary iodine concentration is the prime indicator of nutritional iodine status and is used to evaluate population-based iodine supplementation. In 1994, WHO, UNICEF and ICCIDD recommended median urinary iodine concentrations for populations of 100- 200 micro g/l, assuming the 100 micro g/l threshold would limit concentrations <50 micro g/l to </=20% of people. Some scientists felt this proportion was unacceptably high and wanted to increase the threshold above 100 micro g/l. The study was carried out to determine the frequency distribution of urinary iodine in iodine-replete populations (schoolchildren and adults) and the proportion of concentrations <50 micro g/l.

METHOD

A questionnaire on frequency distribution of urinary iodine in iodine-replete populations was circulated to 29 scientific groups.

FINDINGS

Nineteen groups reported data from 48 populations with median urinary iodine concentrations >100 micro g/l. The total population was 55 892, including 35 661 (64%) schoolchildren. Median urinary iodine concentrations were 111-540 (median 201) micro g/l for all populations, 100-199 micro g/l in 23 (48%) populations and >/=200 micro g/l in 25 (52%). The frequencies of values <50 micro g/l were 0-20.8 (mean 4.8%) overall and 7.2% and 2.5% in populations with medians of 100-199 micro g/l and >200 micro g/l, respectively. The frequency reached 20% only in two places where iodine had been supplemented for <2 years.

CONCLUSION

The frequency of urinary iodine concentrations <50 micro g/l in populations with median urinary iodine concentrations >/=100 micro g/l has been overestimated. The threshold of 100 micro g/l does not need to be increased. In populations, median urinary iodine concentrations of 100-200 micro g/l indicate adequate iodine intake and optimal iodine nutrition.

General pharmacological properties of a new non-opiate antitussive: zipeprol (3024 CERM). I. Action on respiratory function and acute toxicity

1-(2-Methoxy-2-phenyl)-ethyl-4-(2-hydroxy-3-methoxy-3-phenyl)-propyl-iperazine-dihydrochloride (zipeprol, Respilene) is a substance of non-phenanthrenic chemical structure. In the cat, it antagonised cough induced by stimulation of the superior laryngeal nerve or by direct mechanical excitation of the sensitive tracheo-bronchial receptors. The efficacy of zipeprol after enteral administration made it possible both to establish good intestinal absorption and to rank it favourably in relation to several major antitussive reference products; codeine, codethyline, dextromethorphan, diphenhydramine and pentoxyverine. The activity of zipeprol was superior or equal to that of all these substances, excdept codeine. The antitussive properties appeared to be due to a central action. Other properties have been demonstrated which suggest at least a supplementary mechanism in the inhibition of cough, in addition to the central action. These consisted of slight antihistamine and anticholinergic properties, marked local-anesthetic potency and bronchospasmolytic activity. This latter property was demonstrated by the inhibition of histamine and serotonin induced bronchospasm in the guinea-pig. In vitro, using human sputum, zipeprol had a mucolytic action, shown by a decrease in sputum vis viscosity and lysis of DNA and AMPS fibrils. In the dog, at high doses, zipeprol unlike codeine, did not inhibit central stimulation of respiration by hypercapnia, in addition no modification of ventilatory dynamics or blood gases was seen. On the basis of these results, zipeprol can be considered as possessing no respiratory depressant effect even in the upper ranges of its antitussive doses.