Investigational parathyroid hormone replacement effectively treats hypoparathyroidism

An investigational parathyroid hormone replacement effectively treated a rare disorder characterized by low calcium and high phosphate levels in the blood, a new study finds. The results will be presented Saturday at The Endocrine Society's 94th Annual Meeting in Houston.

The parathyroid hormone replacement is called recombinant human parathyroid hormone, or rhPTH(1-84). It is produced in the lab using a replica of the human parathyroid hormone gene. rhPTH(1-84) is identical to the naturally occurring parathyroid hormone and acts to regulate calcium levels in the same way. Calcium is an essential mineral for bone, teeth, and muscle health, among other things.

In the rare and complex disorder known as hypoparathyroidism, or HypoPARA, the parathyroid gland produces insufficient parathyroid hormone. As a result, calcium levels drop, while the amount of phosphate, another mineral, increases in the body. This mineral imbalance can cause a number of symptoms, including muscle twitching, spasms, and pain; seizures; cramps in the hands and feet; fatigue; anxiety; depression; and problems with bone and tooth development.

Current options are limited to symptom management with calcium and active vitamin D in high doses to increase calcium levels. The problem with this approach is that long-term use of high-dose calcium and vitamin D can cause dangerous calcium formations in vital organs, including the kidneys, heart, and brain.

"Hypoparathyroidism is the only classic endocrine deficiency disease for which the missing hormone, in this case parathyroid hormone, is not an approved therapy," said lead study investigator, John P. Bilezikian, professor of medicine, Division of Endocrinology, Columbia University College of Physicians and Surgeons. "This study has the potential not only to fill in this major therapeutic gap by showing the efficacy and safety of parathyroid hormone, but also to markedly improve the management of this disease."

In this study, the largest of its kind, rhPTH(1-84) helped regulate calcium and reduced the amount of calcium and active vitamin D required in more than half of patients, while well tolerated. In contrast, only 2 percent of those who received placebo improved. Also, by the study's end, 41 percent of patients who received rhPTH(1-84) no longer required additional vitamin D and needed ≤ 500mg calcium per day.

"These are important findings for patients with this rare and complex disorder who need more options for care, especially considering the potential threat to the kidneys, heart, and brain associated with the long-term use of high-dose calcium and vitamin D," Bilezikian said.

Investigators randomly assigned 134 patients to receive either the parathyroid hormone replacement or placebo. Patients were 78 percent female, 96 percent white, and their average age was 48 years.

After undergoing adjustments of calcium and active vitamin D doses to normalize blood levels of calcium for at least two weeks, patients received daily injections of rhPTH(1-84) or placebo for 24 weeks. Study visits occurred every four weeks, and neither patients nor investigators knew who was receiving study drug versus placebo in this double-blinded study.

Source: Columbia University College of Physicians and Surgeons

Comments

  1. Sue Sue Canada says:

    This study gives some hope for those that are suffering from hypoparathyroidism. I pray Health Canada approves the PTH replacement soon so the patients with this rare condition can get on with their lives.  I had my thyroid removed in 2010, and have been suffering with the effects of hypoparathyroidism since. The twitching, numbing, depression, cramping, headaches, are symptoms I have on a daily basis.

    • Barb Barb Canada says:

      Hello Sue,

      I had my thyroid (and parathyroids) removed in June....I feel your pain.  I'm getting a little desperate myself...was just surfing for a clinical trial in Canada that I might be able to participate in when I found your post.  More than willing to be a Guinea pig to help find a solution to this.  Are you anywhere near Ottawa?  If you hear of any studies looking for volunteers, please send the info my way.  

      Hang in there!

      Barb

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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