Women with fibromyalgia have a high incidence of hyperparathyroidism, a disease caused by an overactive parathyroid, according to a study titled “High frequency of asymptomatic hyperparathyroidism in patients with fibromyalgia: random association or misdiagnosis?” and published in the journal Revista Brasileira de Reumatologia.

Fibromyalgia and hyperparathyroidism share a range of symptoms, including fatigue, arthralgia, myalgia, sleep disturbances, depression, anxiety and memory impairment, which increase the chances for an improper diagnosis. Primary hyperparathyroidism is a disease caused by a hyperactive parathyroid, which are small endocrine glands located in the neck, next to the thyroid, and responsible for the secretion of a hormone, the parathyroid, that regulates calcium levels in the body.

Researchers determined the frequency of asymptomatic hyperparathyroidism in a sample of patients with fibromyalgia by performing a cross-section study that enrolled 100 women with fibromyalgia and 57 healthy women, as controls. Additionally, they measured the levels of parathyroid hormone, calcium and albumin, correlating them with symptoms in the fibromyalgia group.

Fibromyalgia patients exhibited normal values of mean serum calcium and parathyroid hormone (9.6 ± 0.98 mg/dL and 57.06 ± 68.98 pg/mL, respectively). However, the levels of the parathyroid hormone were significantly higher when compared to the control group. Hypercalcemic (high calcium levels) hyperparathyroidism was detected in 6 percent of patients with fibromyalgia, but only 17 percent of these women had high levels of parathyroid hormone exhibiting normocalcemic (normal calcium levels) hyperparathyroidism. Researchers found no association between hyperparathyroidism and FM symptoms, with the only exception being epigastric pain.

These results show that in women with fibromyalgia a high frequency of hyperparathyroidism and of normocalcemic hyperparathyroidism exists compared to the general population. Researchers note, however, that these results are preliminary and additional studies with a larger number of patients are necessary to determine and confirm the association between the two diseases, fibromyalgia and hyperparathyroidism, and if high levels of parathyroid hormone are a characteristic of fibromyalgia pathophysiology.

Determining calcium and parathyroid hormone serum levels may be important for fibromyalgia patients. If alterations in these parameters are observed, researchers suggest patients should be screened for primary hyperparathyroidism.