Thyroid and calcium relationship

Thyroid and calcium relationship

The highly-organized relationship between the thyroid, the parathyroid and calcium is essential for normal functioning of the human body.

Both the thyroid glands and the parathyroid glands work alternatively, maintaining calcium levels within normal limits through the regulation of calcium levels in both the blood stream and bones. [[1], [2], [3]]

How can the thyroid gland affect calcium levels?

Talking about the thyroid gland is commonly associated with its ability and responsibility for secreting the hormones that regulate metabolism, which makes some think that that the thyroid gland has no more roles.

Importantly, the thyroid gland secretes another hormone named calcitonin, through which the thyroid significantly aids in calcium and phosphorus levels regulation.

When calcium level increases in the blood, the thyroid gland secrets more calcitonin, which in turn plays a dual role, as follows [[4]]:

  • Calcium absorption

Calcitonin improves the absorption rate of both calcium and phosphorus from the blood into bone cells.

  • Effect of osteoclasts

Calcitonin inhibits the effect of certain cells known as osteoclasts, decreasing calcium migration from the bones to the blood stream.

How can the parathyroid glands affect calcium levels?

The parathyroid glands are 4 glands directly located behind the thyroid gland. The main function of the parathyroid glands is to secrete parathyroid hormone, which in turn is responsible for regulating calcium levels in the body, along with calcitonin.

In case calcium decreases in blood stream, that stimulates the parathyroid glands to secrete parathyroid hormone, which increases calcium level in blood through 3 ways, as shown below [[5]]:

  • Calcium migration

Parathyroid hormone improves the activity of osteoclasts, increasing the rate of calcium migration from bones to blood.

  • Kidneys

Through kidneys, parathyroid hormone can controls calcium level, as it inhibits the rate of filtration of both calcium and magnesium, prolonging the time they stay in blood circulation. [[6]]

  • Human gut

Parathyroid hormone also improves the absorption rate of calcium, magnesium and phosphate from the gut, resulting in increasing calcium levels in blood. That occurs as a result of calcium’s stimulatory effects on the kidneys, causing them to synthesize more calcitriol.

That way the thyroid gland and parathyroid glands keep calcium levels within normal limits in both the blood stream and bones all the time.

What makes calcium levels very important?

Calcium is much more important than other elements.

While some are just aware of the role calcium plays in strengthening body bones [[7]]; actually, calcium has much more to do for the body, including:

  • Muscles contraction

Calcium is responsible for the contraction of all the body muscles, such as those of the legs, arms and the heart muscle. That’s why the parathyroid glands tend to increase the calcium level in blood, so as to ensure maintaining sufficient amounts of calcium for the muscles.

  • Nerve conduction

Along with muscles contraction, calcium is also responsible for efficiently conducting signals through nerves.

What if the relationship between calcium, the thyroid and parathyroid glands deteriorates?

In this case, calcium levels would abnormally increase or decrease, making the body much likely to many issues [1]. For example, abnormal calcium accumulation in the blood stream can cause osteoporosis, abnormal nerve conduction and over contraction of body muscles, and more importantly the heart muscle.

In contrast, low calcium level in the blood can result in calcification of bones, less efficient nerve conduction (numbness), and muscle contraction.

What can cause this relationship to deteriorate?

The issues listed below show certain disorders that sometimes occur with the thyroid gland or the parathyroid glands, deteriorating the relationship between calcium and these glands.

  • Hyperparathyroidism

The gland hyperactively works, mistakenly continuing to secrete parathyroid hormone, even when the blood level of calcium is normal or high. That can result in hypercalcemia and kidney stones [[8]].

  • Hyperthyroidism

Hyperthyroidism may result from many issues, such as Grave’s disease, causing the thyroid gland to overly secrete thyroid hormones.

  • Hypoparathyroidism

Hypoparathyroidism occurs when the parathyroid gland secrets less parathyroid hormone than normal, or when the secreted hormone doesn’t work efficiently.

  • Hypothyroidism

Hypothyroidism occurs when the thyroid gland fails to properly secrete enough amounts of thyroid hormones regularly. Its effects are detailed more specifically in the article here.

  • Goiter

Goiter is amongst the cases in which the relationship between calcium level and the parathyroid gland may deteriorate. Goiter refers to a swelling of the thyroid gland, which may affect the gland entirely or only a part.

  • Thyroid cancer

Although thyroid cancer seems to be kind of rare, it also can negatively affect thyroid hormones secretion.

  • Thyroid surgery

If thyroid surgery mistakenly leads to removing one or more of the parathyroid hormones, that is likely to cause the thyroid gland to lose its ability to regulate calcium levels.

How much calcium should people take?

Calcium should be taken daily and cautiously.

The Food and Nutrition Board established 2 types of values in order to help people avoid the harmful effects and disorders that are likely to occur in cases of both calcium deficiency and hypercalcemia [[9]].

Recommended Dietary Allowances of calcium

  • The infants aged 0-6 months are recommended to take 200mg/day; while those ranging from 7 to 12 months are recommended to take 250mg/day.
  • The Children ranging from 1 to 3 years are recommended to take 700mg calcium/day; while those aged 4 to 8 years should take 1000mg calcium daily.
  • The children aged 9-13 years should get 1300mg calcium daily, and so should those ranging from 14 to 18 years.
  • The adults ranging from 19 to 50 years should only get 1000mg calcium daily; while the calcium amount recommended for those ranging from 51 to 70 years differs, according to gender, as follows:
  • Males: 1000mg/day.
  • Females: 1200mg/day.
  • The adults aged 71 years or more are recommended to take 1200mg of calcium daily.
  • The pregnant and breast-feeding women aged 14-18 years should consume 1300mg of calcium daily; while those ranging from 19 to 50 years should only consume 1000mg of calcium daily.


Tolerable Upper Intake Levels of Calcium

The Tolerable Upper Intake Levels show the maximum amount of calcium that can be safely administered daily, as follows [9]:

  • The infants aged 0-6 months are allowed to take calcium up to 1000mg/day; while those ranging from 7 to 12 months are allowed to take up to 1500mg/day.
  • The Children ranging from 1 to 8 years are allowed to take up to 2500mg of calcium/day; while those aged 9 to 18 years are allowed to take up to 3000mg calcium daily.
  • The adults ranging from 19 to 50 years are allowed to administer up to 2500mg calcium daily; while those aged 51 years or older are allowed to only administer 2500mg of calcium/day.
  • The adults aged 71 years or more are recommended to take 1200mg of calcium daily.
  • The pregnant and breast-feeding women aged 14-18 years are allowed to consume up to 3000mg of calcium/day; while those ranging from 19 to 50 years are allowed to only consume 2500mg of calcium daily.

The best sources of calcium

According to the National Institute of Health, the foods listed below should be considered in order to get sufficient amounts of calcium [[10]].

  • Milk, yogurt, and cheese
  • Vegetables, such as Chinese cabbage, kale, and broccoli.
  • Grains fortified with calcium
  • Foods fortified with calcium, such as fruit juices and drinks, tofu, and cereals.

Along with foods, drinks, it’d be beneficial to consider dietary thyroid supplements so as ensure getting adequate amounts of calcium daily, especially for those not eating variant foods, the elderly and the busy people who are much likely to not pay attention to what they eat/or how much calcium they get from each meal, in addition to those struggling with issues that can negatively affect the absorption rate of calcium from the gut.

Many forms of calcium are available in the market, such as calcium gluconate, calcium phosphate and calcium lactate. But, the most common forms are only two, including calcium carbonate and calcium citrate.

  • Calcium carbonate

That is much more common and sheep than calcium citrate. The dietary supplements containing calcium carbonate can be taken either with or without food, as the gastric acids in the stomach can improve their absorption rate.

  • Calcium citrate

As the absorption of calcium citrate is not dependent on the gastric acid, the supplements containing calcium citrate are specifically beneficial to the people struggling with gastric issues, such as low-gastric-acid (achlorhydria ), irritable bowel syndrome and inflammatory bowel disease.


[1]  Begic-Karup S., et al. Serum calcium in thyroid disease. Wien Klin Wochenschr. 2001 Jan 15;113(1-2):65-8.


[2]  Dinesh Kumar Dhanwal. Thyroid disorders and bone mineral metabolism. Indian J Endocrinol Metab. 2011 Jul; 15(Suppl2): S107–S112. doi:  10.4103/2230-8210.83339.


[3] Mohan HK., et al. Thyroid hormone and parathyroid hormone competing to maintain calcium levels in the presence of vitamin D deficiency. Thyroid. 2004 Sep;14(9):789-91.


[4] Inzerillo AM., et al. Calcitonin: the other thyroid hormone. Thyroid. 2002 Sep;12(9):791-8.


[5]  Chen RA., et al. Role of the calcium-sensing receptor in parathyroid gland physiology. Am J Physiol Renal Physiol. 2004 Jun;286(6):F1005-11.


[6]  McCaffrey Ct.,  and Quamme G A., Effects of thyroid status on renal calcium and magnesium handling. Can J Comp Med. 1984 Jan; 48(1): 51–57.


[7] Elias E. Mazokopakis, et al. Interaction between levothyroxine and calcium carbonate. Can Fam Physician. 2008 Jan; 54(1): 39 .


[8]  PTH parathyroid hormone [ Homo sapiens (human) ]. Gene ID: 5741, updated on 8-Oct-2017.


[9] Food and Nutrition Board. DRI Tables and Application Reports. United States Department of Agriculture. National Agricultural Library


[10] Office of Dietary Supplements. Calcium. Fact Sheet for Health Professionals. National Institute of Health. Updated: November 17, 2016.

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