Does surgery for primary hyperparathyroidism (PHPT) improve bone quality?

From the Guidelines

Surgery for primary hyperparathyroidism (PHPT) is highly effective in improving bone quality, with most patients experiencing significant increases in bone mineral density (BMD) and decreased fracture risk after successful parathyroidectomy. The improvement in bone quality is a result of normalized calcium metabolism after the removal of the hyperfunctioning parathyroid gland, which stops excessive bone resorption and allows bone formation to predominate 1.

Key Benefits of Surgery

• Increased bone mineral density (BMD) of 6-8% in the lumbar spine and 3-5% in the hip within the first year post-surgery
• Continued gradual improvements in BMD for 3-5 years
• Decreased fracture risk by approximately 20-30% within 5 years after surgery
• Most substantial BMD increases occur in patients with the lowest pre-operative bone density and highest pre-operative parathyroid hormone (PTH) levels

Post-Surgery Recommendations

• Ensure adequate calcium intake (1000-1200 mg daily) and vitamin D supplementation (800-1000 IU daily) to maximize bone recovery
• Consider additional osteoporosis medications like bisphosphonates for patients with severe pre-operative osteoporosis, though this should be individualized
• Bone density testing is typically recommended 1-2 years after surgery to document improvement 1.

Surgical Approaches

The two accepted curative operative strategies for PHPT are bilateral neck exploration (BNE) and minimally invasive parathyroidectomy (MIP), with MIP being less invasive and often preferred for patients with a single adenoma 1. The choice of surgical approach depends on various factors, including the presence of multigland disease, preoperative localization of the adenoma, and the surgeon's expertise.

Importance of Preoperative Imaging

Preoperative imaging plays a crucial role in localizing the abnormally functioning gland or glands with high accuracy and high confidence, facilitating targeted curative surgery 1. This is particularly important in the reoperative setting, where parathyroid reoperations are surgically challenging and have lower cure rates and higher complication rates. Recent international guidelines emphasize the importance of preoperative imaging in the reoperative setting to localize a target parathyroid lesion (or lesions) and to identify postoperative changes from previous parathyroid explorations that can impact a subsequent surgery 1.

From the Research

Bone Quality Improvement After Surgery for Primary Hyperparathyroidism

• Surgery for primary hyperparathyroidism (PHPT) has been shown to improve bone quality in several studies 2, 3, 4, 5, 6.
• A study published in 2004 found that about 50% of patients had increased bone mass after PHPT surgery, although the increase in bone density was difficult to predict for individual patients 2.
• Another study from 2012 found that bone metabolism normalized and bone mineral density (BMD) of the lumbar spine increased significantly within one year after surgery 3.
• A 2018 review noted that parathyroidectomy has a long-term beneficial effect on the skeleton and is probably prudent to refer PHPT patients for surgery in all cases where increased bone fragility is suspected 4.
• A 2017 study found that baseline 24-hour urinary calcium correlated directly with s-calcium, parathyroid hormone, and bone markers, and that patients with higher baseline 24-hour urinary calcium had greater increases in bone mineral density after parathyroidectomy 5.
• A 2012 study found that bone mineral density improved in up to 75% of patients after curative parathyroidectomy for PHPT, with younger patients and those with severe PHPT deriving the most skeletal benefits from parathyroidectomy 6.

Factors Associated with Bone Quality Improvement

• Younger age has been associated with greater improvement in bone mineral density after parathyroidectomy 6.
• Higher preoperative levels of parathyroid hormone, serum calcium, and urinary calcium have also been linked to greater improvement in bone mineral density 3, 5, 6.
• Baseline 24-hour urinary calcium has been identified as an independent determinant of improvement in bone mineral density 5.
• The use of bisphosphonates before surgery did not affect outcomes in one study 6.

Bone Mineral Density Changes After Surgery

• Studies have consistently shown that BMD increases after parathyroidectomy, particularly in the lumbar spine 2, 3, 5, 6.
• The hip and lumbar spine have been found to respond similarly to surgery in terms of BMD improvement 6.
• Significant improvement in BMD has been observed in up to 38% of patients, with moderate improvement in up to 31% of patients 6.