Subclinical hypothyroidism in pregnancy: consider iodine deficiency before prescribing thyroid hormone treatment
Maraka and colleagues, in their article ‘Thyroid hormone treatment among pregnant women with subclinical hypothyroidism’ (1), do not seem to have considered iodine deficiency (common in pregnancy) as a potential cause, and that it may in fact be iodine supplementation, not thyroid hormone treatment, that is needed.
All pregnant women with elevated TSH (and ideally, all women pre-conception) should be tested for iodine deficiency and receive appropriate iodine supplementation; combined iodine intake from diet and supplements should be between 290 and 1100 µg per day.
Urinary iodine concentration is a good marker of the recent intake of iodine over days, and is the index of choice for evaluating iodine deficiency (spot urine concentrations have been shown to correlate well with 24-hour urine samples).
1. Thyroid hormone treatment among pregnant women with subclinical hypothyroidism: US national assessment. Spyridoula Maraka et al. BMJ 2017;356:i6865
Competing interests: No competing interests