Archive for category Iodine'

Iodine: Practice Points – Patient Counselling. FAQ

• Iodine is an essential trace element required for healthy functioning of the thyroid gland and for normal growth and development. • It is mainly consumed as iodide salts from sea salt, shellfish, seawater fish and vegetables. • Iodine is essential for the manufacture of thyroxine (T4) and triiodothyronine (T3), which are hormones that influence growth, maturation, thermogenesis, oxidation, myelination of the CNS and the metabolism of all tissues. • Iodine supplementation is commonly used to prevent and treat deficiency. There is also some evidence that it may reduce pain in fibrocystic breast disease and cyclic mastalgia and suggestive evidence of a protective role against breast cancer; however, rigorous research is required to confirm these observations. • Current evidence points to widespread mild to moderate iodine deficiency in Australia, suggesting that dietary intake is inadequate and supplementation or fortification of foods with additional iodine may be required. Answers to Patients’ Frequently Asked Questions What will this supplement do for me? Adequate intake of iodine is critical for healthy thyroid function and normal growth and development. Ensuring adequate intake becomes Read more […]

Iodine: Interactions. Contraindications. Pregnancy Use

Significant Interactions GOITROGENS These are substances that interfere with iodine utilisation or thyroid hormone production and include thiocyanates found in the cabbage family (e.g. cabbage, kale, cauliflower, broccoli, turnips and Brussels sprouts) and in linseed, cassava, millet and soybean — separate intake of iodine and goitrogens where possible. SOY The actions of this particular goitrogen are two-fold: ingestion of soy appears to inhibit iodine absorption to some extent (particularly when presented in its thyroxine form in the gut) and also high levels of the isoflavones genistein and daidzein can inhibit T3 and T4 production — separate intake of iodine and goitrogens where possible. Particular attention should be paid to minimising soy consumption in individuals taking thyroid hormone supplementation, as it has been shown that soy consumption can increase dosage requirements. SELENIUM Selenium is intrinsic to the metabolism and activity of the thyroid hormones, facilitating the conversion of T4 to T3 and is also responsible for the only iodine recycling pathway of the body through the action of the deiodinases on excess or unnecessary thyroid hormones to release the iodine— beneficial interaction. Contraindications Read more […]

Iodine: Dosage. Toxicity

Dosage Range AMERICAN AND AUSTRALIAN RDI • Infants 0-6 months: 90 µg/day 7-12 months: 110 µg/day • Children 1-3 years: 90 µg/day 4-8 years: 90 µg/day 9-14 years: 120 µg/day >14 years: 150 µg/day • Adults: 150 µg/day • Pregnancy: 220 µg/day • Lactation: 270 µg/day • Upper level of intake 1-3 years: 200 µg/day 4-8 years: 300 µg/day 9-13 years: 600 µg/day 14-18 years (including pregnancy, lactation): 900 µg/day Adults >18 years (including pregnancy, lactation): 1100 µg/day These are the newly revised American and Australian RDIs, which are more closely aligned with the WHO recommendations than previously. ACCORDING TO CLINICAL STUDIES • ADHD prevention: adequate intake to prevent maternal deficiency (approximately 250 µg/day). • Fibrocystic breast disease and cyclic mastalgia: 500 µg to 6 mg molecular iodine/day. • Breast cancer prevention: dose is unknown; however, it is suggested that women meet RDI to prevent deficiency. • Water disinfectant: 3-5 ppm in water or 8 drops of 2% tincture to approximately 1 L of water. Toxicity Chronic iodine toxicity results when iodide intake is approximately 2 mg daily or greater. Overconsumption Read more […]

Iodine: Other Uses

PREVENTION OF ATTENTION-DEFICIT HYPERACTIVITY DISORDER? Emerging data from research conducted over the past 15 years suggest a possible link between low maternal iodine status and increased risk of ADHD in the offspring. According to a report published in 2004, 11 of 16 children born to women living in a moderately iodine-deficient region in Italy developed ADHD compared to no offspring from the 11 control mothers living in a marginally iodine-deficient region. On the other hand, another group of researchers investigated whether T4 levels at birth could represent a biomarker for later development of ADHD and found that all newborns in the sample had T4 within the normal range and no correlation between values and risk could be demonstrated. This evidence invalidated TSH levels as a biomarker of risk, but does not disprove a link between iodine and ADHD, as earlier studies found that those newborns who later developed ADHD were all euthyroid at birth. Although further investigation is required to clarify these observations, they have provided a new avenue for ADHD research. FIBROCYSTIC BREAST DISEASE AND CYCLIC MASTALGIA A 1993 review that focused on three clinical studies suggests that iodine supplementation Read more […]

Iodine: Clinical Use

Increased iodine intake can be achieved through dietary modification and supplementation with tablets. Dietary modification usually refers to increased intake of iodised salt, but may also refer to use of iodised water, iodised vegetable oil or seafood. TREATMENT AND PREVENTION OF DEFICIENCY Iodine deficiency is accepted as the most common cause of brain damage worldwide, with IDD affecting 740 million people. Although it is well accepted that severe deficiency is responsible, evidence is now emerging that mild deficiency during pregnancy is also important and can have subtle effects on brain development, lowering intellectual functioning and inducing psychomotor deficits in early childhood. Preliminary data are also emerging to suggest an association between iodine deficiency hypothyroidism of pregnancy and the incidence of ADHD in the offspring; however, this still requires confirmation in larger studies. PREGNANCY Severe iodine deficiency is uncommon in Western countries, such as Australia and New Zealand, but several local surveys have identified that mild to moderate deficiency is more prevalent than once thought. A research group at Monash Medical Centre in Melbourne screened 802 pregnant women and found that Read more […]

Iodine: Actions

Main Actions THYROID HORMONE PRODUCTION Iodine is essential for the manufacture of T4 and T3, which are hormones that influence growth, maturation, thermogenesis, oxidation, myelination of the CNS and the metabolism of all tissues. The thyroid hormones, especially T3, exert their effects by binding to nuclear receptors on cell surfaces, which in turn triggers binding of the zinc fingers of the receptor protein to the DNA. Other Actions Due to the concentration of appreciable iodine levels in a range of other tissues, including salivary, gastric and lactating mammary glands, as well as the ovaries, questions remain about the potential for additional actions of iodine. One currently proposed model suggests iodine is an indirect antioxidant, via its capacity to reduce elevated TSH, a trigger of increased peroxide levels in the body. Clinical note — Why is iodine deficiency on the rise? The emergence or re-emergence of iodine deficiency is not limited to Australia. One study found that the median urinary iodine excretion had declined by more than 50% in between 1971 and 1994 in the United States. Three reasons have been proposed to explain the emergence of iodine deficiency in developed countries. First, milk Read more […]

Iodine: Deficiency Signs and Symptoms

PRIMARY DEFICIENCY Iodine deficiency results when iodide intake is <20 µg/day. In situations of moderate deficiency, TSH induces thyroid hypertrophy in order to concentrate iodide, resulting in a goitre. Most of these cases remain euthyroid, but in cases of severe iodine deficiency, myxoedema may result in adults and cretinism in infants, both of which are serious conditions. Myxoedema is characterised by swelling of the hands, face, feet and peri-orbital tissues and can lead to coma and death if sufficiently severe and left untreated. Endemic cretinism is divided into two forms, neurologic or myxoedematous, depending on the interplay of genetics and iodine deficiency. Usually children with neurologic cretinism are mentally deficient and often deaf mute but of normal height and strength and may have goitre. Myxoedematous cretinism is characterised by dwarfism, mental deficiency, dry skin, large tongue, umbilical hernia, muscular incoordination and puffy facial features. Concomitant selenium deficiency may be a contributing factor in myxoedematous cretinism. Early treatment with thyroid hormone supplementation can promote normal physical growth; however, intellectual disability may not be prevented and in very Read more […]

Iodine: Background and Relevant Pharmacokinetics

Iodine is an essential trace element required for the proper functioning of the thyroid gland. It is mainly consumed as iodide salts obtained from sea salt, shellfish and seawater fish and vegetables, which are more bioavailable than the organic form of iodine. The iodine content of soil is considered to be one of the most variable of all mineral levels, influenced by local geography and the type and quantity of fertiliser used in agriculture. The amount of iodine present in local drinking water (0.1 -100 µg/L) is reported to be a good indication of soil levels. In iodine-deficient areas, the iodide concentration in drinking water is <2 µg/L (<1 5.8 nmol/L), whereas in areas close to the sea, the drinking water contains 4 to 10 µg/L (31.5-78.8 nmol/L). Iodide is rapidly absorbed from the small intestine and distributed via the blood to a range of tissues, most notably the thyroid, which traps absorbed iodide through an ATP-dependent iodide pump. The thyroid contains 80% of the body’s iodine pool, which is approximately 15 mg in adults. Some is also found in the salivary, gastric and mammary glands (exclusively during pregnancy and lactation in the latter), as well as in the ovaries. As is the case with the Read more […]