Primary hyperparathyroidism causes hypercalcemia (elevated blood calcium levels) through the excessive secretion of parathyroid hormone (PTH), usually by an adenoma (benign tumors) of the parathyroid glands. Its incidence is approximately 42 per 100,000 people. It is almost exactly three times as common in women as men.
"Bones" refers to bone-related complications. The classic bone disease in hyperparathyroidism is osteitis fibrosa cystica, which results in pain and sometimes pathological fractures. Other bone diseases associated with hyperparathyroidism are osteoporosis, osteomalacia, and arthritis.
Other signs include proximal muscle weakness, itching, and band keratopathy of the eyes.
The diagnosis of primary hyperparathyroidism is made by blood tests. Serum calcium levels are elevated.
The serum chloride phosphate ratio is 33 or more in most patients with primary hyperparathyroidism.  However, thiazide medications have been reported to causes ratios above 33.
Urinary cAMP is occasionally measured; this is generally elevated.
Parathyroid hormone activity
Intact PTH levels are also elevated.
The most common cause of primary hyperparathyroidism is a sporadic, single parathyroid adenoma resulting from a clonal mutation (~97%). Less common are hyperplasia of all parathyroid glands (~2.5%), parathyroid carcinoma (malignant tumor), and adenomas in more than one gland (together ~0.5%). Primary hyperparathyroidism is also a feature of several familial endocrine disorders: Multiple endocrine neoplasia type 1 and type 2A (MEN type 1 and MEN type 2A), and familial hyperparathyroidism.
In all cases, the disease is idiopathic, but is thought to involve inactivation of tumor suppression genes.
The classic bone disease in hyperparathyroidism is osteitis fibrosa cystica, which results in pain and sometimes pathological fractures. Other bone diseases associated with hyperparathyroidism are osteoporosis, osteomalacia, and arthritis.
Treatment is usually surgical removal of the gland(s) containing adenomas.
Medications include estrogen replacement therapy in postmenopausal women and bisphosphonates. Bisphosphonates may improve bone turnover.
Newer medications termed "calcimimetics" used in secondary hyperparathyroidism are now being used in Primary hyperparathyroidism. Their benefits are as yet unclear.
The symptoms of the disease, listed above, are indications for surgery. Surgery reduces all cause mortality as well as resolving symptoms. However, cardiovascular mortality is not significantly reduced
A consensus statement in 2002 recommended the following indications for surgery in asymptomatic hyperparathyroidism:
Serum calcium (above upper limit of normal): 1.0 mg/dl
24-h urinary calcium >400 mg
Creatinine clearance reduced by 30% compared with age-matched subjects.
Bone mineral density t-score <-2.5 at any site
More recently, three randomized controlled trials have studied the role of surgery in patients with asymptomatic hyperparathyroidism. The largest study reported that surgery showed increase in bone mass, but no improvement in quality of life after one to two years among patients with:
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^ Vestergaarde and Mosekilde, BMJ Cohort study on effects of parathyroid surgery on multiple outcomes in primary hyperparathyroidism.2003 Sep 6;327(7414):530-4.Click here to read
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^ Khan AA, Bilezikian JP, Kung AW, et al (2004). "Alendronate in primary hyperparathyroidism: a double-blind, randomized, placebo-controlled trial". J. Clin. Endocrinol. Metab.89 (7): 3319-25. doi:10.1210/jc.2003-030908. PMID 15240609.
^ Vestergaarde and Mosekilde, BMJ Cohort study on effects of parathyroid surgery on multiple outcomes in primary hyperparathyroidism.2003 Sep 6;327(7414):530-4
^ Bilezikian JP, Potts JT, Fuleihan Gel-H, et al (2002). "Summary statement from a workshop on asymptomatic primary hyperparathyroidism: a perspective for the 21st century". J. Clin. Endocrinol. Metab.87 (12): 5353-61. PMID 12466320.
^ Bollerslev J, Jansson S, Mollerup CL, et al (2007). "Medical observation, compared with parathyroidectomy, for asymptomatic primary hyperparathyroidism: a prospective, randomized trial". J. Clin. Endocrinol. Metab.92 (5): 1687-92. doi:10.1210/jc.2006-1836. PMID 17284629.
^ Ambrogini E, Cetani F, Cianferotti L, et al (2007). "Surgery or surveillance for mild asymptomatic primary hyperparathyroidism: a prospective, randomized clinical trial". J. Clin. Endocrinol. Metab.92 (8): 3114-21. doi:10.1210/jc.2007-0219. PMID 17535997.
^ Rao DS, Phillips ER, Divine GW, Talpos GB (2004). "Randomized controlled clinical trial of surgery versus no surgery in patients with mild asymptomatic primary hyperparathyroidism". J. Clin. Endocrinol. Metab.89 (11): 5415-22. doi:10.1210/jc.2004-0028. PMID 15531491.