Miriam E. Tucker

May 01, 2014

BOSTON – For some patients diagnosed with fibromyalgia, parathyroidectomy may be the cure.

In a new study, nearly all patients with primary hyperparathyroidism (PHP) who had a preexisting diagnosis of fibromyalgia (FM) experienced improvement in their FM symptoms following parathyroid surgery, and 1 in 5 were able to drop all of their FM-related medications.

The finding suggests that a subset of patients diagnosed with FM actually have unrecognized PHP, which can be cured with surgery. The implication is that screening for the endocrine condition should be included as part of the FM workup, which it currently is not, Kelly L. McCoy, MD, assistant professor of surgery at the University of Pittsburgh, Pennsylvania, said here at the American Association of Endocrine Surgeons (AAES) 2013 Annual Meeting.

"Look for PHP before diagnosing FM. Even if they really do have FM, they may appreciate significant symptom relief and medication decrease after successful surgery," Dr. McCoy told Medscape Medical News.

Large Symptom Overlap Between 2 Conditions; Screen FM for PHP

Primary hyperparathyroidism, characterized by persistent hypercalcemia in the presence of an inappropriately elevated parathyroid hormone (PTH) level, occurs in up to 0.5% of the US population. Surgical treatment is usually successful.

Fibromyalgia, a poorly understood condition involving widespread musculoskeletal pain, occurs in 0.7% to 6% of the population. The treatment is medical, based on symptoms. The economic burden of FM is estimated at tens of thousands of dollars per patient, and up to a third of patients are unable to work, Dr. McCoy said.

The diagnostic confusion between PHP and FM arises because there is a large symptom overlap between the 2 conditions: in both, patients experience fatigue, musculoskeletal pain, headache, cognitive dysfunction, and mood disturbance. Both conditions are also far more common in women than in men, and both increase with age.

In a recent small study presented at the American College of Rheumatology (ACR) meeting in October 2013, unsuspected PHP was found in 10% of patients diagnosed with FM, in contrast to just 0.1% of the general population.

The current study looked at the connection from the endocrine surgery side: of 2184 patients treated for sporadic PHP, 4% (80) had a prior FM diagnosis.

AAES session moderator Mira Milas, MD, professor of surgery and director of endocrine surgery at Oregon Health & Science University, Portland, told Medscape Medical News that the data align with her experience.

"I completely agree with their findings. It is pretty much the uniform experience of all parathyroid surgeons that many patients who actually have primary hyperparathyroidism have been given a diagnosis of FM....The 4% prevalence found in this study is consistent with my experience. That's not a small number."

Dr. Milas, who was not involved in the study, said she also agrees with Dr. McCoy's call for PHP screening. "The impact of this paper is that it will be exceptionally important to reach out to primary-care doctors, to rheumatologists, and to fibromyalgia centers to present this information and experience and encourage them to do a screening. It's not widely appreciated."

Screening for PHP involves obtaining an initial serum calcium level. If the level is high, the patient then needs further lab work, including calcium, parathyroid hormone, vitamin D, and possibly 24-hour urine calcium levels. "It is very easy to screen for PHP," Dr. McCoy told Medscape Medical News.

Fibromyalgia Symptom Relief

In their study, Dr. McCoy and colleagues queried a prospectively maintained parathyroidectomy database to identify patients who had undergone the operation during 1995–2013. For the analysis, they included all patients who had biochemical confirmation of PHP, had been offered the surgery according to symptoms and published guidelines, and had a minimum of 6 months of follow-up.

Of the 80 total patients with a prior diagnosis of FM, complete data were available for 74. All were women, with a mean age of 61 years. The majority (55) had 3 or more FM/PHP symptoms. Half (53%) were taking anti-inflammatory drugs, 35% were on narcotics, 31% were taking fibromyalgia-specific drugs, and 28% were on antidepressants.

Compared with the 2110 patients with PHP only, the 74 with both FM and PHP were significantly more likely to have musculoskeletal symptoms (100% vs 54%), fatigue/depression (96% vs 57%), cognitive decline/memory loss (62% vs 31%), and headache (19% vs 10%).

Parathyroidectomy produced a durable PHP cure — defined as a normal serum calcium level at 6 months or longer postoperatively — in all but 1 (97%) of the PHP/FM patients.

Symptoms were assessed by the provider and by a standardized questionnaire beginning in 2011. Over a mean follow-up of 14 months (range, 6–57), 89% of the FM/PHP patients reported improvement in at least 1 symptom and 25% reported improvement in all 4 of the FM/PHP symptoms. Cognitive function was the most commonly improved symptom, reported by 80%, followed by fatigue in 71%, pain in 55%, and depressive symptoms in 39%.

As their symptoms improved, 84% of the patients stopped taking at least 1 medication, and 21% dropped all their FM/PHP medications. Anti-inflammatories were the most commonly dropped class of drugs, followed by narcotics, antidepressants, and FM-specific drugs.

A Proportion of FM Patients Could be Misdiagnosed

The 21% was "the most significant and somewhat surprising finding" of the study, Dr. McCoy said, leading the investigators to suspect that in those patients at least, the FM might have been a misdiagnosis and they actually had only PHP.

On the symptom questionnaire, 54% of the FM/PHP patients reported general wellness, and 57% noted improved quality of life following surgery (P = .01 for both).

Dr. Milas told Medscape Medical News, "The key take-home message is that all patients who are potentially diagnosed with FM or carry that diagnosis, wherever they are in their course of treatment, should be screened for parathyroid disease."

Dr. McCoy added that she is hoping to soon launch a multi-institutional study to expand on the preliminary findings reported at the ACR meeting, investigating the prevalence of PHP among patients seen at FM clinics around the country.

"These patients are labeled as sick, and they may have something that we can fix. I think it's really crucial to do a bigger study so we can get this out there."

Neither Dr. McCoy and colleagues nor Dr. Milas have disclosures.

American Association of Endocrine Surgeons 2014 Annual Meeting; April 29, 2014; Boston, Massachusetts. Abstract 38.


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