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• Low Iodine Diet
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• Other Related Health Issues
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Other Related Health Issues

1. What is the likelihood of developing a secondary cancer as a result of External Beam Radiation (EBR) treatment for thyroid cancer, and which cancers is one more at risk of developing? If there is increased risk, what is the usual lag time between the canc

   ANSWER by DR. JAMES BIERLEY (January, 2011):
   External beam radiotherapy can cause second cancers many years or decades after radiation treatment. The commonest types of second cancers are breast, lung, and thyroid soft tissue. Generally to be considered to be a second cancer that may be caused by external beam radiotherapy the tumour is within previously irradiated tissue, the time from radiotherapy to secondary malignancy is biologically plausible (at least 5 years usually much longer), and the second malignancy is a different histology from the primary.
   
   The salivary gland tumour and the spinal cord tumour, although unusual as second cancers, could be if they were in the area that received some radiation. Her oncologist should be able to answer this for her.
   
   The type of delivery of the radiation; cobalt or linear accelerator, does not affect the risk.

2. Comment on the results of a large study suggesting that there may be an association between calcium supplementation and a greater chance of heart attacks: http://www.bmj.com/cgi/reprint/341/jul29_1/c3691.

   Cheng (Sept 1/10)

   The recent article in the British medical journal is a meta-analysis of 15 trials of patients receiving either calcium supplements or placebo. Cardiovascular disease was not the primary outcome of any of those 15 trials ... It just happened to be recorded as well. The meta-analysis found that there was an increase in heart attacks among those that got calcium compared to those that did not. However, there are several important points to note when interpreting these results:
   
   1. The actual number of events was very low (2.7% in the calcium group vs. 2.2% in the placebo group)
   2. The cardiovascular events were not checked - just reported by the investigators. Also, since it was not a primary outcome, we can never be sure that the data were collected properly
   3. The patients in these trials received calcium alone - with no vitamin d. That does not happen in real life.
   4. People with thyroid cancer, having had a thyroidectomy, were not included in any of these trials
    
   For all of the above reasons, I do not feel that there is cause for concern for thyroid cancer patients who are on calcium supplements because of low parathyroid levels after surgery. As for those with normal parathyroids, taking calcium supplements because of suppression of TSH, the recommendation is to take only the amount needed to total 1500 mg per day (on top of whatever is in your diet). In addition, vitamin D is recommended too at a dose of at least 1000 iu per day. Remember that the meta-analysis did not include people on both calcium and vitamin D. There is no cause for concern but there is also no need to take excessive calcium (>1500 mg /d), unless instructed to do so on the basis of low parathyroid levels.
   
   Ezzat (Sept 1/10)

   The concern regarding excessive calcium intake has been recently highlighted by the referenced study. Fortunately, in the case of patients with thyroid cancer, calcium intake is aimed to restore levels to their normal state. This is particularly relevant in cases where the parathyroid glands were sacrificed during neck node dissection for thyroid cancer surgery. Loss of normal parathyroid hormone function leads to impaired vitamin D activation and diminished calcium absorption. Supplementation with active vitamin D (such as Rocaltrol) to permit calcium absorption and calcium itself is required to achieve normal calcium levels. The doses required to achieve this effect varies depending on the individual. Inappropriately low calcium levels are also harmful leading to increased heart and brain irritability. Hence, close monitoring of blood and possibly urinary calcium levels are best at determining the appropriate supplementation doses for each patient.

3. Are thyroid cancer survivors are more likely to experience acid reflux and other digestive complaints in the years after surgery?

   Ezzat (May 1/10)

   There are many causes for gastro-esophageal refluxing disease (GERD) often referred to as "heart burn" however, thyroid cancer and/or disease is not one of them. Typically refluxing is associated with weakening of the muscles that close the upper and lower outlets of the stomach. This results in reverse flow of food contents into the feeding tube (esophagus). The presence of acidic fluid exacerbates the discomfort as it is sensed by the body as an abnormal irritation. The consumption of acidic formulations of calcium supplements, not thyroid hormone, is much more likely to worsen heart burn. However, it can interfere with thyroid hormone absorption which is why it is recommended that thyroid meds be taken on an empty stomach with no other food or pills for at least one hour.

   Cheng (May 1/10)

   I am not aware of any data linking thyroid cancer to gastro-esophageal reflux disease (GERD) or other digestive complaints. However, it is not uncommon for people who take calcium supplements (for any reason) to have some stomach related side effects. To deal with that, one can try taking the calcium supplement with food. Alternatively, there are a number of different calcium formulations available on the market and it may be worthwhile speaking to your pharmacist and trying different ones out there.
   
   
    

4. Weight gain post thyroidectomy surgery -- fact or fiction?

   Ezzat (Aug 1/09)

   It's true that thyroid hormone levels can fluctuate widely in patients undergoing total thyroidectomy. For most, correction with synthetic thyroid hormone restores levels to their normal state and corrects the associated symptoms of fatigue and weight gain. For unclear reasons, however, some patients continue to battle with perpetual weight gain despite thyroid hormone replacement. It is advisable to take preventative measures by maintaining a regular exercise and dietary routine to avoid post thyroidectomy weight problems.
   
   Cheng (Aug 1/09)

   After a total thyroidectomy, every effort is made to achieve a normal thyroid hormone level as soon as possible. Therefore, there should be little impact on weight. However, there is a period of time immediately after surgery when some patients may reduce their activity levels and that may result in some weight gain. Once the TSH free T4 and free T3 levels have been normalized, the weight should stabilize and patients need to reduce their oral intake and increase their physical activity as needed to lose weight. As is always the case with weight management, every individual is different and even within the same individual, different times in their lives will also affect the ability to lose or gain weight.
   
    

5. Does the action of Methotrexate (prescribed to treat rheumatoid arthritis and other maladies) -- specifically its ability to suppress the immune system -- increase the probability of having a thyroid cancer recurrence?

   Ezzat (July 1/09)
   This is an important question in many ways. Immunosuppressive agents such as methotrexate have the potential to significantly reduce the immune systems response. This can include evasion by cancer cells and escape from normal surveillance. As such, patients receiving such medications are instructed to undergo careful monitoring throughout the course of treatment. At all times, the risks versus benefits from such medications must be weighed and treatment modified accordingly.

   
   Cheng (July 1/09)
   Methotrexate is a commonly prescribed disease-modifying anti-rheumatic drug (DMARD) and given its immunosuppression properties, questions have been raised about its relationship with cancer. A 2008 study published in the journal, Arthritis & Rheumatism, examined 459 patients with rheumatoid arthritis and methotrexate-exposure and determined cancer risk. Those treated with methotrexate had a 50% increase in the overall risk of cancer compared to the general population. The increase in risk was primarily for melanoma (3-fold increase), Non-Hodgkin's lymphoma (5-fold increase) and lung cancer (3-fold increase). There was only 1 case of thyroid cancer out of the 456 study patients and that case occurred after the methotrexate had finished. Therefore, at this time, there are no data linking methotrexate use and thyroid cancer.
   
    

6. Is it safe for thyroid cancer patients to consume alcohol?

   Drucker (Dec 1/05)

   (Regarding the use of alcohol) there is very little good scientific information on this topic in adult human subjects. Patients with profound hypothyroidism or hyperthyroidism may be more sensitive to alcohol intake, however good studies are lacking. Very minimal hypo-or hyperthyroidism is unlikely to be influenced by moderate (1-2 drinks) alcohol intake. However, since both thyroid hormone and alcohol can affect your heart, muscles, and central nervous system (memory, cognition, sleep etc), if a patients is experiencing symptoms attributable to these organs, it seems prudent to avoid or greatly reduce alcohol intake until the thyroid condition is appropriately treated.

7. Can TSH suppression therapy (ie. having a very low TSH) affect muscle mass and/or heart disease?

   Ezzat (Oct 1/05)

   There is no evidence that high thyroid hormone with a suppressed TSH results in loss of muscle mass. There is concern however, that too high thyroid hormone can predispose patients to heart muscle problems. This balance between keeping the TSH low and avoiding excessive doses of thyroid hormone on the heart must be reviewed.

8. What effect do cough and cold medications have an on those with hyperthyroidism?

   Drucker (Jan 1/06)

   A large number of medicines are available, generally not requiring a prescription, to treat the cough or symptoms of a cold or flu. Many of these medicines carry warnings about potential problems if the patient has thyroid disease. These medicines can be subdivided generally into two groups; those that contain iodine or those that contain adrenergic agonists (stimulants) such as ephedrine, norepinephrine, pseudoephedrine, terbutaline, adrenaline, or xylometazoline.

   Iodine is taken up and used by the thyroid to make thyroid hormone. In patients with untreated hyperthyroidism, administration of iodine can make the hyperthyroidism worse. However, once treatment with medications such as PTU or methimazole has been started, excess iodine is blocked from being incorporated into the thyroid hence cough and cold medicines are usually safe to take. Small amounts of iodine may precipitate hyperthyroidism or hypothyroidism in previously normal patients, however this is also uncommon. Patients already taking thyroid hormone have a very low risk of having any new thyroid-related problems develop if they take cough and cold medicines containing iodine.

   Medicines containing ingredients such as ephedrine, pseudoephedrine, adrenaline, noradrenaline, or xylometazoline (adrenergic agonists) are often used to constrict dilated blood vessels in those, in order to relieve sinus or nasal congestion, reduce stuffiness and improve breathing. These medicines if taken in sufficient doses may also increase the heart rate and blood pressure. Similarly, patients taking medicines for asthma that contain adrenaline, salbutamol (Ventolin), terbutaline or related drugs may also note an increase in heart rate, nervousness and tremor. Since patients with moderate to severe hyperthyroidism may experience palpitations, tremor, increased sweating, rapid heart beats, and increased blood pressure, the class of cough and cold medicines that contain adrenergic agonists should be used with caution under a physician’s supervision until the hyperthyroidism is brought under control.

   Patients who have had complete removal of their thyroid and who are already taking thyroxine do not need to be as concerned about taking medications containing small amounts of iodine or adrenergic stimulants.

   Editor’s Note:If you are preparing for an RAI scan or ablation and should avoid these products because of the iodine content. See: www.mythyroid.com/coughandcoldremedies.html

9. Should thyroid cancer patients be taking vitamin D supplements?

   Cheng (Feb 1/08)

   Given that we live in Canadaand have minimal sun exposure, in fact NO useful sun exposure from October to May, most of us are vitamin D deficient. The study that was released in June  was performed in post-menopausal women and demonstrated reduction in cancers.  There are other studies to suggest benefit for reducing fractures and autoimmune diseases.  There are no different recommendations for those with cancer or autoimmune disease.  The 1000 IU recommendation can be applied to everyone, with or without cancer.

10. What should thyroid cancer patients know about calcium?

    Chui (April 1/08)

    Of the different forms of calcium available, calcium carbonate and calcium citrate are the most popular. Others also exist e.g. calcium gluconate, calcium phosphate, calcium lactate, and calcium from dolomite and bone meal (although high in elemental calcium, calcium supplements made of dolomite and bone meal have been found to contain lead and other toxic metals and as such are not recommended).

    When considering which form of calcium to take, the most important thing to look at is its elemental calcium content (the amount of calcium the body is able to absorb) and how it relates to the needs of the individual in question. Always check the label to see how much elemental calcium is supplied by each tablet. If the label doesn't state the amount of elemental calcium, you can figure it to be:

    • 40 percent for calcium carbonate

    • 21 percent for calcium citrate

    • 13 percent for calcium lactate

    • 9 percent for calcium gluconate

    This means that if you take 1,000 mg of calcium carbonate, you will get 40 percent elemental calcium, or 400 mg.

    Calcium citrate is the form of calcium most often recommended by doctors, chiefly because it is the most easily absorbed - it does not require extra stomach acid for absorption, so it can be taken on an empty or a full stomach. On the other hand, calcium citrate provides less calcium per pill than calcium carbonate, so you may need to take more pills than you would if you took calcium carbonate. In addition, in spite of its stomach-friendly reputation, it may cause stomach upset or diarrhea in certain individuals. Even they are better tolerated that Calcium Carbonate, Calcium Citrate may still cause constipation in some sensitive patients.

    Calcium Carbonate is the other most widely used and least expensive form of calcium. It is not as easily absorbed as calcium citrate, but is the most concentrated form of calcium with elemental calcium and the most cost-effective calcium supplement. However, because it is alkaline-based, you need extra stomach acid to absorb it. As such,calcium carbonate is best taken right after meals. This form of calcium has also been known to cause constipation and bloating. If you take this, it is a good idea to drink more water than usual and take it in two or more doses, rather than all at one time. (Note: Calcium carbonate is also found in products like Tums and Rolaids, in the antacid section of the pharmacy. If you opt for this form of calcium, read the label carefully and make sure you don't get an antacid that includes aluminium because that can leach calcium from your system). Some patient may experience constipation with this form and taking it with Magnesium can help.

    Calcium Lactate and Calcium Gluconate are less concentrated forms of calcium and are similar to calcium citrate in terms of absorbability and lack of side effects. However they usually cost more than calcium citrate - as much as three to ten times more, making them cost-prohibitive for the average consumer.

    Tribasic Calcium Phosphate contains roughly 39% elemental calcium and is another easily digested form of calcium. It is also the type of calcium used to fortify many foods such as orange juice and soy milk. However, it is also among the most expensive forms of calcium.

     

    Calcium Supplements Rules of Thumb

    It is a good idea to take your calcium multiple times during the day, instead of in one dose, because your body can absorb only about 600 milligrams of elemental calcium at a time.

    Avoid taking calcium supplements at the same time as any medication that needs to be taken on an empty stomach. Also don't take them at the same time as tetracycline (an antibiotic), iron supplements, thyroid hormones, or corticosteroids, because calcium binds to these substances, interfering with their effectiveness and also its own absorption. Keep in mind that taking calcium with high-fibre meals or bulk laxatives can cut down on the amount of calcium you absorb.

    There is no difference between calcium products derived from natural or synthetic sources. It is more a matter of personal preference. Calcium derived from oyster shells is likely to be cheapest and you can get as much as 500 mg to 600 mg of elemental calcium in one tablet. However, there are concerns that the natural forms of calcium supplements may contain significant amounts of heavy metals such as lead. There are also coral based Calcium products, which are derived from fossilized coral reefs. Coral calcium is comprised of calcium carbonate and trace minerals. Coral Calcium are generally more expensive than oyster based products. It may also have the same contaminations due to the pollutants in the environment. Coral Calcium is a salt of calcium derived from fossilized coral reefs. Coral calcium is comprised of calcium carbonate and trace minerals.

    As discussed above, Calcium is best absorbed in an acidic environment. Calcium Carbonate is alkaline based and so it requires extra stomach acid. It is best taken right after a meal as food stimulates the stomach to secrete more gastric acid. Calcium citrate, on the other hand, has good solubility at low pHs (acidic environment). This means it is more readily absorbed and utilized by the body and can be taken on an empty stomach.

    For the reasons outlined above, calcium citrate may be a better choice for older individuals, especially those experiencing problems with digestion due to decreased stomach acid production when you age.

    There are many calcium supplements that include magnesium and Vitamin D in their formulations. The most current research indicates that contrary to popular advertising, magnesium does not improve calcium absorption. However magnesium deficiencies are common, particularly in women. Magnesium improves bone mineral density and has been shown to be theoretically beneficial for osteoporosis. In addition, taking Magnesium together with Calcium will help to prevent constipation.

    On the other hand, adequate Vitamin D intake is vital to ensure maximum calcium absorption. Vitamin D increases intestinal calcium absorption. Without vitamin D, the small intestine absorbs only about 10% to 15% of dietary calcium.

    The parathyroid glands secrete PTH, a substance that helps maintain the correct balance of calcium and phosphorus in the body. PTH regulates the level of calcium in the blood, the release of calcium from bone, absorption of calcium in the intestine, and excretion of calcium in the urine. When the level of calcium in the blood falls too low, the parathyroid glands secrete just enough PTH to restore the blood calcium level.

    Patients that have lost parathyroid function (such as patients who underwent Total Thyroidectomy and did not get a successful Parathyroid Re-implantation), they have no regulatory process to correct calcium deficits and develop chronic low calcium levels, therefore, require large dose of calcium and vitamin D supplementation.

    Most Calcium Carbonate and Citrate on the market are not oyster or coral based. Therefore, it is safe to be taken Low Iodine Diet. They are not dairy-based and most do not have other additives such as dye or sodium chloride. But it would be wise to read the label carefully before consuming any products if patients are on special diets.

11. Is there a relationship between thyroid cancer and iron deficiency? Do estrogen levels play a part?

    Ezzat (Oct 15/06)

    There is no known specific relationship between iron deficiency and thyroid cancer. Very rarely, the same individual can have two cancers. One in the thyroid, and another in the colon leading to blood loss with consequent iron deficiency. Another rare occurrence is the female with a pituitary tumor and Acromegaly. This condition predisposes to both thyroid cancer and uterine fibroids. Again, the latter can be a source of blood loss and hence iron deficiency.

    Estrogen is not typically recognized as a promoter of thyroid cancer development or progression. It does, however, promote uterine fibroid growth.

12. Is there a relationship between thyroid cancer and Hashimoto's thyroiditis?

    Ezzat (Nov 1/06)

    Hashimoto's thyroiditis and papillary thyroid cancer are two common thyroid conditions. An active search over the years has failed to identify a causal relationship between the two. In other words, having one condition does not predispose you to develop the other. Moreover, treatment of one does not influence the other.

    The probably of thyroid cancer is not influenced by the presence/absence of hashimoto's thyroiditis. It is more likely, however, that patients with thyroiditis will have positive anti-thyroid antibodies which can confound the measurement of thyroglobulin that is used in monitoring cancer recurrence. This must be accounted for when interpreting results in the follow-up of the thyroid cancer patient.