Hyperthyroidism

In hyperthyroidism, the metabolic demand increases on the body, putting a stress on the heart.

There’s various degrees of severity on hyperthyroidism.

• The most severe form of hyperthyroidism is thyrotoxicosis (thyroid storm) which puts a major strain on the heart. This can cause an otherwise healthy heart to fail because the body asks too much from it.
  • Symptoms include
    • ophthalmopathy (bulging of the eye)
    • high cardiac output failure.

Treatment of Hyperthyroidism

These are the drugs we could use:

1. Propylthiouracil (Propacil)
2. Methimazole (Tapazole)
3. Potassium Iodide (SSKI)
4. Sodium Iodide I-131

1: Propylthiouracil (PTU; Propacil)

2: Methimazole (Tapazole)

Both of these drugs work on inhibiting the production of T3 and T4.  Most treatments don’t cure anything, but these have a chance of actually curing the hyperthyroidism. About 70-80% of patients go into complete remission and discontinue the drug. The other 30% may remain on therapy for life or use an alternative form of therapy such as radioactive therapy.

Contraindication: Pregnancy because these drugs crosses into the placenta. If an individual is pregnant or breast feeding they must not take it because it will stop the thyroid activity of the child.

3. Super Saturated Potassium Iodide (High concentration of Iodide)

A high concentration of iodide for treating hyperthyroidism sounds backwards but it actually works because the excess amount of iodide causes the negative feedback loop to kick and slow down thyroid activity. But it only for a short time of 72 hours. What’s the benefit of giving them a drug that works only for 72 hours? If an individual has a very severe form of hyperthyroidism (thyroid storm), they’re probably a candidate for removing a part of the thyroid gland so that it produces less of the hormone (but not too much so they won’t be hypothyroid). A hyperthyroid individual can’t go into surgery because their heart will be racing and it doesn’t go well with anesthetics.

The government provides SSKI for individuals who live near a nuclear reactor in case of a disaster so they don’t absorb the radioactive iodine. We have seen one example of this with the meltdown of Chernobyl. The reactor melted down and released radioactive iodine. For the people who lived, they absorbed all that radioactive iodide and it went into their thyroid gland. Down the road they developed thyroid cancer. Since SSKI only lasts for 72 hours, the point of the government giving it is for you to take it and you get the fuck out of that area.

• High concentration provides negative feedback to thyroid gland for 72 hours
• Pre-operative use to prepare patient for surgery
• Example: Super Saturated Potassium Iodide (SSKI)
  • Also used as an expectorant

4. Sodium Iodide I-131 (Radioactive Iodide)

This is another therapy and it’s an extremely low dose of radioactive iodide. It’s actually a solution (a couple drops) you drink. The radioactive iodide congregates in the thyroid gland to destroy a part of it. We typically don’t try to cure somebody with the first dose so that we don’t risk overshooting it and making them hypothyroid for life. We wait about 2-3 months before we give a second dose, based on their response. If you were wrong in your calculation and gave too much, they would have hypothyroidism for the rest of their life and need thyroid replacement therapy.

The advantage of this is that you avoid surgery. The disadvantage is that you still need to have a precise dose calculated.

Recap for Radioactive Iodide (sodium iodide I-131)

• Onset of action: days to weeks
• Remission: 2-3 months
• 25 to 33% of patients cured after 1 dose
• Advantage: Avoid surgery
• Disadvantage: Exact dose needed
• Contraindication: pregnancy because it stops development of the baby, children because children are developing.