Endocrine Abstracts

Objectives: Recent Germany-wide studies have shown that urinary iodide excretion in schoolchildren as well as in adults meet WHO targets. No current results for pregnant women in Germany are available.

Methods: We investigated urinary iodide excretion in 1003 pregnant women on the day of childbirth in the greater Rostock area. Iodide was measured by cerarsenite method modified by Lorenz. Domestic use of iodized table salt and intake of iodine supplement tables was tracked using a questionnaire. We also determined urinary nitrate excretion (u.v. detection at 245 nm following ultrafiltration of the urine and isocratic separation by ion chromatography) and the serum thiocyanate concentration (pyridine/barbituric acid method).

Results: Iodine contamination occurred in 168 women after caesarean section due to the use of the skin disinfectant povidone-iodine (Braunol). These women were excluded from analysis. In the remaining sample population of 714 women that had a spontaneous vaginal delivery, the median urinary iodide excretion was 103.3 μg I ⁻/l. Relative iodine excretion distribution: 46% >100 μg I ⁻/l, 32% 50–99 μg I ⁻/l, 12% 20–49 μg I ⁻/l, 10% >20 μg I ⁻/l.

Median urinary iodide excretion in women using iodized table salt (91%) was 104 μg I ⁻/l and 102.8 μg I ⁻/l in women that did not use iodized table salt. Iodide excretion relative to iodine supplement intake: no intake – 92.3 μg I ⁻/l; 100 μg per day – 95.8 μg I ⁻/l; 200 μg per day −112.9 μg I ⁻/l. The values for thiocyanate (5.08 mg SCN ⁻ /l) and nitrate (44.22 mg NO₃⁻/ml) were below the respective goitrogenic threshold and correlated with neither urinary iodide excretion nor thyroid volume obtained by sonography.

Conclusions: In Germany, women during pregnancy and in early puerperium remain significantly undersupplied with iodine (recommended daily amount 230–260 μg). These women require intake of iodine supplements particularly if their diet is low on iodine. The relevant goitrogens SCN ⁻ and NO₃⁻ do not interfere.