Calcium Regulation in the Body: Exploring the Role of Hormones

Did you know how calcium gets regulated in our body? Calcium is an essential mineral for bone and teeth health and plays many crucial functions in the body. If its levels are not maintained it leads to severe symptoms. In our body, many hormones regulate calcium in the body. Learn about the role of hormones in calcium regulation in our body in this article. Log on to for a consultation.



Exploring the Role of Hormones in calcium regulation

Calcium is an essential mineral in the body. The body uses different hormones to regulate calcium throughout the body to maintain its levels in the normal range. Here are the main hormones that help in calcium regulation:

  1. Vitamin D:

While vitamin D is not a hormone, it plays a particularly vital role in regulating long-term serum calcium with a half-life of around 6 hours. The main function of vitamin D in the body is to increase the intestinal absorption of calcium.

You can either ingest it or synthesize it from a cholesterol precursor as follows:

  • 7-dehydrocholesterol is converted into vitamin D3 under the influence of UV radiation from sunlight. The liver converts vitamin D3 into 25-hydroxyvitamin-D, which is mostly inactive.
  • The kidney converts 1-α-hydroxylase into 25-hydroxyvitamin-D into 1, 25-dihydroxyvitamin-D, otherwise known as calcitriol, which is metabolically active.

Once synthesized, calcitriol gets released into the bloodstream which stimulates intestinal epithelial cells to increase the synthesis of calbindin-D proteins. Calbindin-D proteins can increase the intestinal absorption of calcium by facilitating the transport of calcium from the intestinal brush border to the basolateral membrane, where it is released into the bloodstream.

If levels of calcitriol become excessive, then it gets converted into 24, 25-dihydroxy cholecalciferol, which is a less active chemical and prevents toxicity.


  1. Parathyroid hormone (PTH):

When the amount of calcium drops below the normal range in the blood, cells of the parathyroid gland get active and produce additional PTH in the body. PTH raises blood calcium levels by:

  • Increasing bone resorption: PTH can bind osteoblasts and regulate the protein called RANKL. This stimulates pre-osteoclasts to differentiate into osteoclasts which resorb bone and release calcium into the bloodstream.
  • Increasing renal reabsorption of calcium: PTH upregulates the specific channels of the distal convoluted tubule (DCT). This leads to increased reabsorption of calcium into the blood and also increases the excretion of phosphate.
  • Increasing synthesis of calcitriol: PTH triggers the kidney to convert 1-α-hydroxylase into 25-hydroxyvitamin-D into 1, 25-dihydroxy vitamin-D, which is the conversion of the relative inactive form into calcitriol.


Additionally, PTH and calcitriol inhibit the secretion of PTH from the parathyroid gland. However, this sends a negative feedback loop to ensure blood calcium levels don’t rise or go above the normal range.


  1. Calcitonin:

Besides parathyroid hormone and calcitriol, the third main calcium regulation hormone is called calcitonin. This is produced by parafollicular cells of the thyroid gland when calcium levels rise in the blood. It decreases calcium levels by inhibiting osteoclasts which reduce bone resorption and decreases the flux of calcium from bone into blood. It also suppresses the renal tubular reabsorption of calcium which enhances the excretion of calcium into urine. This hormone plays a significant role in bone development and calcium regularly in the early stages of life. However, in adults its role is not long-lasting. Excessive high or low levels of calcitonin don’t cause problems with blood calcium concentration or bone strength. However, it can still be used as a drug to treat bone disease.


Need help with hormonal imbalances that affect your bone health, visit our endocrinology clinic in Brooklyn to get professional medical help. Want to learn what symptoms occur when you have calcium disorders? Call us on +13473845690 and get answers for all your queries. Log on to or visit us at 1797 Pitkin Avenue, Brooklyn, NY 11212 to book an appointment with our endocrinologist to get the best treatment. We have the best endocrinologists who treat these kinds of diseases and helpful staff to aid you during your treatment.