Iodine

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Enlarged thyroid gland in a Domestic shorthair cat

Iodine is an essential mineral in feline nutrition.

Iodine is an essential nutrient, primarily as a component of thyroxine (T4) and triiodythyronine (T3), two hormones responsible for regulation of the thyroid gland in cats.

In a recent case-control study, cats consuming commercial foods without iodine supplementation were more than four times as likely to develop hyperthyroidism compared to iodine-supplemented diets[1]. The response of the feline thyroid to iodine deficiency or excess leads to chronic stimulation of the gland in order to produce sufficient thyroid hormones, leading to hypertrophy and eventual nodular hyperplasia[2]. During periods of iodine excess, iodine transport into the thyroid is temporarily inhibited, and stimulation of the thyroid to release thyroid hormones is decreased through negative feedback to the anterior pituitary[3].

Nearly all commercial cat foods today are supplemented with some form of iodine[4]. The most common iodine supplements are potassium iodide, calcium iodate and, to a lesser extent, ethylene dihydroiodide. Natural supplements include dry kelp, iodized salt and sea salt[5].

Recommended daily iodine requirements in adult cats is 460 μg/kg dry diet[6].

References

  1. Edinboro, CH et al (2004) Review of iodine recommendations for commercial cat foods and potential impacts of proposed changes. Thyroid 14:722
  2. Delange, FM & Ermans, AM (1996) Iodine deficiency. In Braverman LE & Utiger (Eds): Werner and Ingbar's the thyroid: a fundamental and clinical text. Lippincott-Raven, Philadelphia. pp:296-316
  3. Nagataki, S & Yokohama, N (1996) Autoregulation: effects of iodine, In Braverman, LE & Utiger (Eds). Werner and Ingbar's the thyroid: a fundamental and clinical text. Lippincott-Raven, Philadelphia. pp:241-247
  4. Edinboro, CH et al (2010) Feline hyperthyroidism: potential relationship with iodine supplement requirements of commercial cat foods. JFMS 12:672-679
  5. Coffman, HD (1997) The cat food reference. PigDogPress, Nashua
  6. Wedekind, KJ et al (2010) The feline iodine requirement is lower than the 2006 NRC recommended allowance. J Anim Physiol Anim Nutr 94:527-539