Relationship of Iodine Ingestion to Iodine Excretion in Pregnancy

Dworkin, Howard J.; Jacquez, John A.; Beierwaltes, William H.

doi:10.1210/jcem-26-12-1329

Cited by 55 publications

(52 citation statements)

References 3 publications

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“…However, in addition to the enhanced demand for iodine, renal clearance of iodine increases during pregnancy (Aboul-Khair et al, 1964), resulting in increased urinary losses of iodine compared to the nonpregnant state. Dworkin et al (1966) speculated that when customary intakes of iodine were low, the body could compensate by using circulating iodide more efficiently, thereby reducing urinary losses. This theory seems to be supported by data compiled by Smyth (1999) from a variety of population studies.…”

Section: Discussionmentioning

confidence: 99%

Seasonality in urinary and household salt iodine content among pregnant and lactating women of the plains of Nepal

et al. 2003

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Objective: To determine the extent and causes of iodine deficiency among women during pregnancy and lactation in the southeastern plains of Nepal. Design, Setting and Subjects: Urinary iodine (UI) was assessed as an indicator of iodine status in spot urine samples of women participating in a field trial in three rural communities in the plains of southeastern Nepal. Samples were collected during pregnancy (n ¼ 1021) and during lactation at 3-4 months postpartum (n ¼ 1028) at a central clinic; 613 women were assessed at both times. Salt iodine (SI) content was assessed semiquantitatively at 6-7 months postpartum in households (n ¼ 1572). Results: During pregnancy and lactation, median UI concentrations were 0.756 and 0.483 mmol/l, respectively, indicating mild iodine deficiency. UI and SI concentrations covaried markedly by season and were highest during hot, dry, premonsoon months and lowest during and following the humid monsoon season. Within women who contributed urine samples during both pregnancy and the postpartum period, iodine status determined by UI was not correlated. The percentage of households with adequately iodized salt (30 ppm) ranged from 85 to 44% from the hot, dry to the humid seasons, respectively. Conclusions: In the rural southern plains of Nepal, iodine deficiency remains a mild-to-moderate public health problem among pregnant and lactating women despite the availability of iodized salt. Marked seasonality in SI content may account for the lack of intraindividual correlation between maternal iodine status during pregnancy and postpartum periods and contribute to periodicity in the risk of iodine deficiency.

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Section: Discussionmentioning

confidence: 99%

Seasonality in urinary and household salt iodine content among pregnant and lactating women of the plains of Nepal

et al. 2003

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“…An estimated daily iodine uptake by the thyroid gland of about 75 21 , with no significant differences pre-and post-partum 19 . Several authors have measured the thyroid volume during pregnancy and correlated it with the UI concentration and the effects of iodine supplements.…”

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The impact of iodised salt or iodine supplements on iodine status during pregnancy, lactation and infancy

Zimmermann

2007

Public Health Nutr.

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Objectives: Monitoring of iodine status during pregnancy, lactation and infancy is difficult as there are no established reference criteria for urinary iodine concentration (UI) for these groups; so it is uncertain whether iodized salt programs meet the needs of these life stages. Design and Subjects: The method used in this paper was: 1) to estimate the median UI concentration that reflects adequate iodine intake during these life stages; and 2) to use these estimates in a review of the literature to assess whether salt iodisation can control iodine deficiency in pregnant and lactating women, and their infants. Results: For pregnancy, recommended mean daily iodine intakes of 220-250 mg were estimated to correspond to a median UI concentration of about 150 mg l 21 , and larger surveys from the iodine sufficient countries have reported a median UI in pregnant women $ 140 mg l 21 . Iodine supplementation in pregnant women who are mild-tomoderately iodine deficient is beneficial, but there is no clear affect on maternal or newborn thyroid hormone levels. In countries where the iodine intake is sufficient, most mothers have median breast milk iodine concentration (BMIC) greater than the concentration (100-120 mg l 21 ) required to meet an infant's needs. The median UI concentration during infancy that indicates optimal iodine nutrition is estimated to be $ 100 mg l 21 . In iodine-sufficient countries, the median UI concentration in infants ranges from 90-170 mg l 21 , suggesting adequate iodine intake in infancy. Conclusions: These findings suggest pregnant and lactating women and their infants in countries with successful sustained iodised salt programs have adequate iodine status.

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“…, the iodine balance during pregnancy becomes negative 21 . The WHO, the UNICEF and the ICCIDD 19 recommend a daily iodine intake of 200 mg day 21 by pregnant women, a 33%…”

mentioning

confidence: 99%

“…The WHO, the UNICEF and the ICCIDD 19 recommend a daily iodine intake of 200 mg day 21 by pregnant women, a 33%…”

mentioning

confidence: 99%

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Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition

Delange

2007

Public Health Nutr.

173

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Objective: This paper re-evaluates the requirements for iodine during pregnancy, lactation and the neonatal period, and formulates original proposals for the median concentrations of urinary iodine (UI) that indicate optimal iodine nutrition during these three critical periods of life. This paper also discusses the measurements that are used to explore thyroid functions during the same periods. Design: An extensive and critical review of the literature on thyroid physiopathology during the perinatal period. Setting: Human studies conducted in various regions throughout the world. Subjects: Pregnant women, lactating women, and newborns. Results: The following proposals are made after extensive review of the literature: the requirement for iodine by the mother during pregnancy is 250-300 mg day -1 ; during lactation the requirement is 225-350 mg day -1 ; and during the neonatal period the requirement of the infant is 90 mg day -1 . The median UI that indicates an optimal iodine nutrition during these three periods should be in the range of 150-230 mg day -1 . These figures are higher than recommended to date by the international agencies. Conclusions: Pregnant women and young infants, but especially the second group, are more sensitive to the effects of an iodine deficiency (ID) than the general population because their serum thyroid-stimulating hormone (TSH) and thyroxine are increased and decreased, respectively, for degrees of ID that do not seem to affect thyroid function in the general population. Systematic neonatal thyroid screening using primary TSH could be the most sensitive indicator to monitor the process of ID control.

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Relationship of Iodine Ingestion to Iodine Excretion in Pregnancy

Cited by 55 publications

References 3 publications

Seasonality in urinary and household salt iodine content among pregnant and lactating women of the plains of Nepal

Seasonality in urinary and household salt iodine content among pregnant and lactating women of the plains of Nepal

The impact of iodised salt or iodine supplements on iodine status during pregnancy, lactation and infancy

Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition

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