Iodine is essential for the synthesis of thyroid hormones and both hypothyroidism and iodine deficiency are prevalent worldwide. Assessing iodine status in the individual is difficult. Spot urine iodine measurement, while readily available, is not accurate. However, combining the clinical picture with a brief dietary history along with this simple measurement may give further insight into the likely iodine requirements of an individual. Supporting nutritional deficiency in subclinical hypothyroidism is proposed to be helpful in reducing possible requirements for pharmacological intervention in the future although further studies are needed in this area. This is of particular importance in high-risk groups such as those trying to conceive, or patients with subfertility or recurrent miscarriage.
In this case report a 66-yr-old woman with symptomatic subclinical hypothyroidism presents with a low dietary intake of iodine and a correlating low urine iodine. These three factors taken together suggested a possible iodine deficiency. Replacement of iodine with a safe and moderate amount of iodine (75 µg/day, 50% RDA) via supplement and counselling the patient to increase simple sources of iodine in the diet restored euthryoidism and resolved all symptoms.
We propose a simple strategy for the frontline healthcare provider to estimate iodine requirements in an individual-correlating a brief dietary history, low urine iodine and suboptimal thyroid function tests. We recommend that supplementation to increase iodine is conservative and in the short-term only to avoid iodine excess. Dietary intake of iodine should be encouraged to maintain levels thereafter.