Natpara Cuts Risk of Chronic Kidney Disease in Half: Study
Research drew on response of 118 patients who took part in 1 of 4 clinical trials
People with hypoparathyroidism who are on replacement therapy with Natpara, a version of the parathyroid hormone (PTH), are about half as likely to develop chronic kidney disease than patients who don’t receive the therapy, a study found.
The study, “The risk of chronic kidney disease development in adult patients with chronic hypoparathyroidism treated with rhPTH(1-84): A retrospective cohort study,” was published in the journal Clinical Endocrinology.
Hypoparathyroidism happens when the parathyroid glands in the neck are underactive and don’t make enough PTH, a hormone that helps the body control its levels of calcium, phosphorus, and vitamin D. This results in too little calcium and vitamin D, and too much phosphate (a molecule that contains phosphorus) in the blood.
The standard treatment to ease the symptoms of hypoparathyroidism are calcium and active vitamin D (calcitriol), but these supplements fail to control phosphate levels. Moreover, long-standing supplementation may put a strain on the kidneys and lead to complications such as chronic kidney disease.
An alternative would be to replace the missing hormone with a lab-made version that may hold all three levels in check. Natpara, a PTH replacement therapy approved for hypoparathyroidism, is used as an add-on to calcium and calcitriol when they fail to work well enough.
To know whether replacement therapy may also save the kidneys from damage, researchers in Denmark and the U.S. compared the risk of chronic kidney disease among hypoparathyroidism patients who received Natpara and those who didn’t.
They drew on data from 118 patients who took part in either of four clinical trials: REPLACE (NCT00732615), RELAY (NCT01268098), RACE (NCT01297309), and HEXT (NCT01199614) and its continuation study (NCT02910466). Natpara was injected under the skin of the thigh using a special pen. The doses varied from 25 to 100 micrograms depending on the trial and the injections were given every day. (In one group, injections were given every other day.)
The team also selected 497 control patients who did not receive Natpara from a large U.S. database called Explorys.
Those who received Natpara were a mean 6.2 years younger than the controls (45.3 vs. 51.5). Diabetes and some types of disease of the heart or the blood vessels, including hypertension (high blood pressure), were significantly less common among Natpara-treated patients.
When the researchers examined how many patients developed chronic kidney disease over five years, the proportion was lower among those who received Natpara than among controls (11% vs. 27.4%). After taking into account the initial differences between the two groups, the researchers found that those who received Natpara had a 53% lower risk, or about half the chance, of developing chronic kidney disease.
Compared with controls, those on Natpara also had a 65% lower risk of having a sustained drop (by 30% or more) in the estimated glomerular filtration rate (eGFR), a measure of kidney function. This means Natpara may help save the kidneys from damage over time.
One limitation of the study is the lack of information about the amount of calcium and calcitriol taken. Another is that all those who received Natpara took part in clinical trials. They “may have had more frequent evaluation of their condition and reporting of biochemical parameters relevant to this study compared with those in the control cohort, who were seen in real-world clinical practice,” the researchers wrote, noting more research was needed to confirm their findings and understand how Natpara might preserve kidney function in chronic hypoparathyroidism.
The study was funded by Takeda Pharmaceuticals, which markets Natpara.