Iodine deficiency in hypertensive patients
Patients diagnosed with hypertension are routinely advised to limit salt intake. However, the correlation between hypertension and salt intake has been questioned by some, while salt-less food is found tasteless by many. Also, salt iodized with KI (Potassium Iodide) is an important source of iodine in many countries, especially in areas, where iodine insufficiency has been detected. Insufficient intake of salt if coupled with nutritional iodine deficiency from other sources may lead to hypothyroidism with resulting myriad of related symptoms, such as lack of energy, sadness, and fatigability, sleep and eating disturbances, difficulty concentrating, etc., as part of the overall slowed down metabolism.
That includes hyperlipidemia and depression, both independent variables, which may lead to Coronary Artery Disease (CAD). The Recommended Daily allowance (RDA) for iodine is 80 to 100 µg, with the optimal diet intake between 150 and 300 µg. Doses, which greatly exceed the RDA can lead to either hypothyroidism or hyperthyroidism. Iodine deficiency in adults also occurs when iodine intake is less than 20 mg/day. Most of iodine is obtained by ingestion of iodized salt (70 mg/g), some from water (varies from 2 to 10 mg/L depending on proximity to the sea), soil, seaweeds (in Asia), and from fish. Iodine sufficiency is assessed by measurement of urinary iodide excretion, which is expected to be more than 10 mg/dl.
The deficiency of iodine causes thyroid enlargement, which is an attempt to concentrate iodine. This deficiency could be due to deliberate avoidance of salt in iodine-poor environment, as often the hypertensive patients are advised to do. Once a diagnosis of iodine deficiency related hypothyroidism is made, iodide supplementation then becomes essential as in the form of KI to prevent a further progression to a more advanced stage . Plasma thyroid-stimulating hormone (TSH) levels are monitored until they are in the normal range. By monitoring TSH levels, and responding therapeutically to even the low normal ones, one can prevent a cascade of events leading not only to hypothyroidism but also to depression, myocardial infarct and many other complications.
There is a need to inform the public about proper iodine supplementation, especially so when advising to use (iodized) salt sparingly, as in the case of hypertensive patients.
Adam H. Zynger Feb.20, 2004