Jod-Basedow effect vs. Wolff-Chaikoff effect

The Jod-Basedow effect is hyperthyroidism following administration of iodine or iodide either as a dietary supplement or as contrast medium.

This phenomenon is an iodine-induced hyperthyroidism, typically presenting in a patient with endemic goiter who then relocates to an iodine-abundant geographical area.

It is named for Karl Adolph von Basedow, a German physician and the German word for iodine, "jod". It is the opposite of the Wolff-Chaikoff effect.

Carl Adolph von Basedow (1799 – 1854)

The Wolff–Chaikoff effect is a reduction in thyroid hormone levels caused by ingestion of a large amount of iodine.

It is an autoregulatory phenomenon that inhibits organification (oxidation of iodide) in the thyroid gland, the formation of thyroid hormones inside the thyroid follicle, and the release of thyroid hormones into the bloodstream.

This becomes evident secondary to elevated levels of circulating iodide. The Wolff–Chaikoff effect lasts several days (around 10 days), after which it is followed by an "escape phenomenon" which is described by resumption of normal organification of iodine and normal thyroid peroxidase function.

The Wolff–Chaikoff effect can be used as a treatment principle against hyperthyroidism (especially thyroid storm) by infusion of a large amount of iodine to suppress the thyroid gland. 

Iodide was used to treat hyperthyroidism before antithyroid drugs such as propylthiouracil and methimazole were developed. Hyperthyroid subjects given iodide may experience a decrease in basal metabolic rate within 24 hours that is comparable to that seen after thyroidectomy. The Wolff–Chaikoff effect also explains the hypothyroidism produced in some patients by several iodine-containing drugs, including amiodarone.

Iodine Intake - the official recommendations

The daily Dietary Reference Intake recommended by the United States Institute of Medicine is 

1. between 110 and 130 µg for infants up to 12 months, 

2. 90 µg for children up to eight years, 

3. 130 µg for children up to 13 years, 

4. 150 µg for adults, 

5. 220 µg for pregnant women and 

6. 290 µg for lactating mothers.

Electron shell diagram for Iodine, the 53rd element in the periodic table of elements.

The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day (1.1 mg/day).

 The tolerable upper limit was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone.

The thyroid gland needs no more than 70 micrograms /day to synthesize the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of body systems, including lactating breast, gastric mucosa, salivary glands, oral mucosa, thymus, epidermis, choroid plexus, etc. 

The high iodide-concentration of thymus tissue in particular suggests an anatomical rationale for this role of iodine in the immune system.

The trophic, antioxidant and apoptosis-inductor actions and the presumed anti-tumour activity of iodides has been suggested to also be important for prevention of oral and salivary glands diseases.

Natural sources of iodine include sea life, such as kelp and certain seafood, as well as plants grown on iodine-rich soil. 

Iodized salt is fortified with iodine.

As of 2000, the median intake of iodine from food in the United States was 240 to 300 μg/day for men and 190 to 210 μg/day for women.

 In Japan, consumption is much higher, owing to the frequent consumption of seaweed or kombukelp.

It should also be noted that information processing, fine motor skills, and visual problem solving are improved by iodine repletion in moderately iodine-deficient children.