Miriam E. Tucker

April 17, 2013

CHICAGO — Primary hyperparathyroidism (PHPT) is more common than previously thought and often goes unrecognized because physicians aren't checking parathyroid (PTH) hormone levels in over half of patients with hypercalcemia, new research suggests.

The findings, from a large electronic medical record (EMR) review, were reported April 15 by Danielle Press, MD, an endocrine surgery fellow at the Cleveland Clinic, Ohio, here at the American Association of Endocrine Surgeons 2013 Annual Meeting.

Although most physicians who frequently treat PHPT "have suspected the disease to be more common than has been documented, this study confirms that suspicion," Dr. Press told Medscape Medical News. "It also begins to elucidate clinician behavior regarding PHPT, demonstrating a need for change," she added, noting that potential consequences of untreated PHPT include accelerated bone loss, kidney stones, and neurocognitive deficits such as poor concentration, fatigue, and decreased memory.

Session moderator Gerard M. Doherty, MD, chief surgeon at Boston Medical Center, Massachusetts, told Medscape Medical News that this paper is important because it highlights that "we're really underdetecting" PHPT. Elevated calcium should trigger a second measurement to make sure the first reading isn't spurious, and if the second reading is also high, a PTH measurement should be obtained, he noted.

Doctors Not Checking PTH in Those With High Calcium

PHPT is the most common cause of hypercalcemia in the outpatient setting. It has a reported prevalence of just 0.1%, but Dr. Press and her colleagues hypothesized that this figure may be higher, based on their observations that patients referred to them for parathyroid surgery had often gone many years with elevated calcium and/or PTH levels.

Of 2.7 million patients who had a primary-care physician in the Cleveland Clinic's system, they identified a total of 54,198 who had serum calcium values above 10.5 mg/dL. Of those, 7269 were seen during the designated 2-year study period (2008 – 2009), with only 95 (1.3%) of these patients receiving a diagnosis of PHPT documented in the EMR.

Another 2337 patients (32%) had a PTH level measured, but no PHPT diagnosis. The remaining 4837 (67%) did not have PTH measurements taken.

Of the 32% for whom PTH had been obtained but who had no diagnosis listed, 1662 (71%) had PTH levels of 30 pg/mL or higher, making them likely to have PHPT, Dr. Press said.

Among the 4837 who did not have PTH measurements taken, 200 charts were chosen randomly and were analyzed for trends in calcium values, the presence of typical comorbidities for PHPT, and alternative diagnoses that might explain the hypercalcemia. Based on that assessment, approximately 28% were deemed likely to have PHPT.

Of the entire study population of 7269, a total of 43% were deemed likely to have PHPT, including 23% for whom PTH had been obtained, 18.7% who did not have PTH obtained, the 1.3% diagnosed with PHPT, and the less than 1% referred for surgery.

The data translate to an overall prevalence of 0.86% for PHPT in the Cleveland Clinic population, much higher than the previously quoted 0.1%, Dr. Press said.

Clinician Behavior Needs to Change; EMR Will Help

The likelihood of PHPT was highest, 36%, among those with calcium levels in the moderately elevated range (11.1 – 11.5 mg/dL). Above 12.0 mg/dL, the likelihood of PHPT diminished to 11% and other causes became more likely.

Doctors were more prone to measure PTH with increasing calcium levels, but even in the highest calcium group (greater than 12 mg/dL), PTH had been checked in only slightly more than 50% of people, Dr. Press said.

Female patients were significantly more likely than male patients to have had PTH checked, as were those with kidney stones and those with osteoporosis, but still only half of people with these 2 conditions had the measurement taken. "We would expect that to be more like 100%," Dr. Press said.

"What you see here is a reflection of clinician behavior," she noted. "Our findings indicate that educational outreach regarding diagnosis and management of this critical disease is warranted," she concluded.

Session moderator Dr. Doherty said that this study also points to the need for EMRs. "These patients are often asymptomatic… This is an example where an EMR can be very helpful. If you program in that if a patient has elevated calcium they should have this workup, it will get done. If we leave it up to practitioners reviewing stacks of lab reports deciding what to do next, we don't do very well."

But of course, he noted, the Cleveland Clinic already has an EMR and is a leader in quality care measures, "and even they're not doing it as well as they would like."

Neither Dr. Press nor Dr. Doherty has reported relevant financial relationships.

Annual Meeting of the American Association of Endocrine Surgeons, Abstract 13, presented April 15, 2013.

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