Objective To assess iodine status in four separate groups — pregnant women, postpartum women, patients with diabetes mellitus and volunteers. Design and setting Prospective cross‐sectional study at a tertiary referral hospital in Sydney. Participants 81 pregnant women attending a “high risk” obstetric clinic; 26 of these same women who attended three months postpartum; 135 consecutive patients with diabetes mellitus attending the diabetes clinic for an annual complications screen; and 19 volunteers. There were no exclusion criteria. Methods Spot urine samples were obtained, and urinary iodine was measured by inductively coupled plasma mass spectrometer. Outcome measures Iodine status based on urinary iodine concentration categorised as normal (>100 μg/L), mild deficiency (51–100 μg/L) and moderate to severe deficiency (<50 μg/L). Results Moderate to severe iodine deficiency was found in 16 pregnant women (19.8%), five postpartum women (19.2%), 46 patients with diabetes (34.1%) and five volunteers (26.3%). Mild iodine deficiency was found in an additional 24 pregnant women (29.6%), nine postpartum women (34.6%), 51 patients with diabetes (37.8%) and 9 normal volunteers (47.4%). Median urinary iodine concentration was 104 μg/L in pregnant women, 79 μg/L in postpartum women, 65 μg/L in patients with diabetes mellitus and 64 μg/L in volunteers. Conclusions The high frequency of iodine deficiency found in our participants suggests that dietary sources of iodine in this country may no longer be sufficient. Further population studies are required.

Iodine deficiency in the postpartum period has the potential to affect neonatal neuropsychointellectual development. We performed a cross-sectional study involving 50 postpartum women and their neonates, measuring maternal urine iodine, breast milk iodine, and neonatal thyroid stimulating hormone (TSH), and examining their interrelationships. Women were studied at a median (range) of 4 (3-9) days postpartum. Moderate to severe iodine deficiency (defined by urine iodine concentration < 50 microg/L) was found in 29 of the 50 subjects (58%). The median +/- standard deviation (SD) urine iodine was 46.8 +/- 28.5 microg/L and the mean urine iodine expressed in micrograms per gram of creatinine was 86.6 +/- 45.6. The median (range) breast milk iodine was 84.0 microg/L (25.0-234.0). Breast milk iodine was significantly correlated with urine iodine in micrograms per gram of creatinine (r = 0.52, p < 0.001) but not with urine iodine measured in micrograms per liter (r = 0.19, p = 0.2). Six percent of neonates had whole-blood TSH values of greater than 5 mIU/L. Neonatal TSH levels were positively correlated with higher breast milk iodine (r = 0.42, p = 0.003). There was no significant correlation between neonatal TSH levels and the mother's urine iodine content. There is a high prevalence of iodine deficiency in these lactating postpartum subjects. Urine iodine as micrograms per gram of creatinine is a good predictor of breast milk iodine content. In our study, higher breast milk iodine was correlated with a higher neonatal TSH. The impact of breast milk iodine content on neonatal TSH levels and neuropsychointellectual development needs further study.

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Objective:To determine whether thyroid-stimulating hormone (TSH) concentrations in a large sample of neonates meet World Health Organization criteria for an iodine-replete population (< 3% of neonates with whole-blood TSH concentrations > 5 mIU/L), and, in a small subset of neonates, to examine the correlation between maternal urinary iodine and neonatal TSH concentrations. Design: Cross-sectional study of neonatal whole-blood TSH values obtained as part of a routine newborn screening program. Setting: Royal North Shore Hospital (RNSH) in northern Sydney. Participants: Two anonymous samples of neonates born at RNSH (1316 infants born between August 1998 and April 1999 and 1457 infants born between 1 March and 31 December 2000); and 84 infants whose mothers had attended RNSH between September 1998 and August 1999 and supplied a urine sample for iodine measurement. Main outcome measures: Iodine status of neonates (proportion with whole-blood TSH values > 5 mIU/L), and urine iodine concentrations of pregnant women. Results: In the two large population samples of neonates, 8.1% (95% CI, 6.6%-9.5%) and 5.4% (95% CI, 4.3%-6.6%), respectively, had whole-blood TSH values > 5 mIU/L (prevalence range for mild thyroid deficiency, 3%-19%). Comparing the TSH values of the 1316 anonymous infants and the 84 identified infants showed no difference between the proportions with TSH values > 5 mIU/L (8.1% v 10.7%, respectively; P = 0.39). Urine iodine concentrations in the 84 pregnant women indicated borderline mild iodine deficiency. TSH values in their 84 infants were positively correlated with maternal urine iodine concentrations. Conclusions: Our results suggest that the population of northern Sydney may have mild iodine deficiency. However, the expected relationship between maternal MJA 2002; 176: 317-320 urine iodine levels and neonatal TSH concentrations was not found.

Background:Chromium is an essential element in human nutrition. Serum concentrations of chromium are not well characterized during pregnancy or in gestational diabetes mellitus. Objective: The objective of this study was to determine whether low plasma chromium concentrations (≤ 3 nmol/L) are associated with altered glucose, insulin, or lipid concentrations during pregnancy. Design: The study was conducted prospectively and took place at the medical obstetric clinic of a tertiary referral hospital. Seventy-nine women with abnormal results of a 50-g glucose challenge test in the third trimester of pregnancy were studied. All women had a formal 75-g oral-glucose-tolerance test, and fasting insulin, lipid, and chromium concentrations were determined. Chromium was measured by graphite furnace atomic absorption spectrometry. Results: The median chromium concentration was 2 nmol/L (95% CI: 0, 12). There were no significant differences in age, plasma glucose, insulin, lipids, calculated insulin resistance, or calculated ␤ cell function between women with normal and those with abnormal (≤ 3 nmol/L) chromium concentrations. Conclusions: Plasma chromium during pregnancy does not correlate with glucose intolerance, insulin resistance, or serum lipids. Plasma chromium concentrations may not accurately reflect tissue stores of chromium. Several trials showed a beneficial effect of chromium supplementation on glucose tolerance, insulin, and lipids. A method for assessing body chromium stores is required to allow further study.Am J Clin Nutr 2001;73:99-104.