All About Your Thyroid

thyroid gland imagesWhat is the Thyroid?

The thyroid is a small gland, shaped like a butterfly, located in the lower part of your neck. The function of a gland is to secrete hormones. The main hormones released by the thyroid are triiodothyronine, abbreviated as T3, and thyroxine, abbreviated as T4. These thyroid hormones deliver energy to cells of the body.

T3 and T4 production and action

Thyroxine is synthesised by the follicular cells from free tyrosine and on the tyrosine residues of the protein called thyroglobulin (TG). Iodine, captured with the "iodine trap" by the hydrogen peroxide generated by the enzyme thyroid peroxidase (TPO)[2] and linked to the 3′ and 5′ sites of the benzene ring of the tyrosine residues on TG, and on free tyrosine. Upon stimulation by TSH (see below), the follicular cells reabsorb TG and proteolytically cleave the iodinated tyrosines from TG, forming T4 and T3 (in T3, one iodine is absent compared to T4), and releasing them into the blood. Deiodinase enzymes convert T4 to T3[3]. Thyroid hormone that is secreted from the gland is about 90% T4 and about 10% T3[1].

Cells of the brain are a major target for thyroid hormone. Thyroid hormones play a particularly crucial role in brain development during pregnancy[4]. A transport protein (OATP1C1) has been identified that seems to be important for T4 transport across the blood brain barrier[5]. A second transport protein (MCT8) is important for T3 transport across brain cell membranes[5].

In the blood, T4 and T3 are partially bound to thyroxine-binding globulin, transthyretin and albumin. Only a very small fraction of the circulating hormone is free (unbound) - T4 0.03% and T3 0.3%. Only the free fraction has hormonal activity. As with the steroid hormones and retinoic acid, thyroid hormones cross the cell membrane and bind to intracellular receptors (α1, α2, β1 and β2), which act alone, in pairs or together with the retinoid X-receptor as transcription factors to modulate DNA transcription

What Diseases and Conditions Affect the Thyroid?

The most common problems that develop in the thyroid include:

  • Hypothyroidism — An underactive thyroid.
    - Hashimoto’s thyroiditis / thyroiditis
    - Ord’s thyroiditis
    - Postoperative hypothyroidism
    - Postpartum thyroiditis
    - Silent thyroiditis
    - Acute thyroiditis 
    - Iatrogenic hypothyroidism
  • Hyperthyroidism — An overactive thyroid.
    - Thyroid storm
    - Graves-Basedow disease
    - Toxic thyroid nodule
    - Toxic nodular struma (Plummer’s disease)
    - Hashitoxicosis
    - Iatrogenic hyperthyroidism
    - De Quervain thyroiditis (inflammation starting as hyperthyroidism, can end as hypothyroidism)
  • Goiter — An enlarged thyroid.
    - Endemic goitre
    - Diffuse goitre
    - Multinodular goitre 
  • Thyroid Nodules — Lumps in the thyroid gland.
  • Thyroid Cancer — Malignant thyroid nodules or tissue.
    - Papillary
    - Follicular
    - Medullary
    - Anaplastic
  • Thyroiditis — Inflammation of the thyroid.

Treatment

Medical treatment

Thyroid drugs are an important part of treatment for many patients. When you’re looking for an effective thyroid supplement product, you should only consider a product that uses high quality ingredients that have the potential to improve mood and concentraion, support and boost thyroid function, improve energy levels, increase metabolic rate for weight control, and improve overall quality of life.

We evaluated 35 of the top all natural thyroid products on the market today. These products are ones that we feel offer the safest and most effective thyroid support. You may not see the product you use or are interested in using on this list, chances are it did not rank in the top 5.

We are constantly reexamining and updating our rankings because of the availability of new products all the time. To see which thyroid supplements came out on top in our research, be sure to check out our product reviews.

Thyroid surgery

 Surgery is usually performed for thyroid cancer, for some cases of goiter or nodule, and less commonly, as a hyperthyroidism treatment.

Radioiodine therapy

Large goiters that cause symptoms, but do not harbor cancer, after evaluation, and biopsy of suspicious nodules can be treated by an alternative therapy with radioiodine. The iodine uptake can be high in countries with iodine deficiency, but low in iodine sufficient countries. The 1999 release of rhTSH thyrogen in the USA, can boost the uptakes to 50-60% allowing the therapy with iodine 131. The gland shrinks by 50-60%, but can cause hypothyroidism, and rarely pain syndrome cause by radiation thyroiditis that is short lived and treated by steroids.