Understanding the Root Cause of Metabolic Bone Disease: A Case Study Highlighting Hyperparathyroidism

Metabolic bone disorders represent a complex group of conditions that affect bone strength and integrity, often leading to fractures and chronic pain. Identifying the underlying cause is critical for effective treatment and long-term recovery. This case study explores how secondary symptoms such as limb pain and pathological fractures can be linked not to cancer or trauma, but to an endocrine imbalance—specifically primary hyperparathyroidism caused by a parathyroid adenoma.

Case Overview: From Misdiagnosis to Recovery

A 46-year-old female presented with persistent right upper limb discomfort lasting six months. Initially manageable and not significantly aggravated by movement, the pain failed to improve with rest or conventional therapy. Over the past two months, her condition worsened progressively. Twenty days prior to admission, she experienced sudden, severe pain in the same arm accompanied by noticeable swelling—though without redness or warmth—prompting immediate medical evaluation.

Initial imaging at a local facility revealed fibrous dysplasia of the right ulna and radius. However, standard treatments provided no relief. Upon referral to our center—First Affiliated Hospital of Xi'an Jiaotong University—in September 2019, further diagnostic workup uncovered a more profound issue rooted in metabolic dysfunction rather than musculoskeletal injury alone.

Diagnostic Journey: Uncovering Hidden Clues

At presentation, physical examination showed normal skin temperature over the affected area and no signs of infection or acute inflammation. The absence of typical trauma history raised suspicion for non-traumatic causes of fracture. An X-ray confirmed pathological fractures in both the humerus and ulna on the right side.

Advanced Imaging Findings:

CT scan revealed osteolytic lesions in the mid-to-upper humerus and distal ulna.
Multifocal lytic changes were also observed in the ribs and iliac bones—findings initially suggestive of metastatic disease.
Whole-body bone scintigraphy demonstrated diffusely increased skeletal metabolism, particularly in the skull and multiple long bones.
Dual-energy X-ray absorptiometry (DEXA) testing indicated severe osteoporosis with a T-score of -3.7.

Laboratory Results Point Toward Endocrine Dysfunction

Blood tests played a pivotal role in redirecting the diagnosis away from malignancy:

Elevated serum calcium: 2.89 mmol/L (normal range: 2.2–2.6 mmol/L)
Low phosphorus: 0.58 mmol/L (normal: 0.81–1.45 mmol/L)
Markedly elevated alkaline phosphatase: 1,141 U/L (normal: 35–100 U/L)
Parathyroid hormone (PTH) level: 1,063.0 pg/mL (dramatically above normal)

These results strongly supported a diagnosis of primary hyperparathyroidism. Tumor markers, complete blood count, erythrocyte sedimentation rate (ESR), and urine Bence-Jones protein were all within normal limits, effectively ruling out multiple myeloma or other neoplastic processes.

Treatment Plan: Surgical Intervention and Supportive Care

The definitive treatment plan included surgical removal of the abnormal gland. A left inferior neck exploration was performed, identifying and excising a parathyroid adenoma. The procedure was completed successfully without intraoperative complications.

Postoperatively, orthopedic management focused on stabilizing the existing fractures:

Casting of the right upper extremity
Calcium supplementation to prevent post-surgical hypocalcemia
Vitamin D support to enhance calcium absorption

This combined approach addressed both the hormonal imbalance and its structural consequences on the skeleton.

Recovery and Long-Term Outcome

The patient remained hospitalized for 10 days following surgery. During this time, pain levels decreased significantly, and no adverse events occurred. She was discharged in stable condition with instructions for follow-up visits at 1 month, 3 months, 6 months, 1 year, and 3 years post-op.

At the 3-month visit, cast immobilization was discontinued. By the 1-year mark, radiographic imaging confirmed complete healing of the fractures. Repeat thyroid function tests showed normalized PTH and calcium levels. The patient resumed daily activities without limitations and reported high satisfaction with her outcome.

Why Accurate Diagnosis Matters

This case underscores a crucial point in clinical medicine: not all fractures are due to trauma or cancer. Metabolic bone diseases like those induced by hyperparathyroidism can mimic malignancy, leading to unnecessary anxiety and potentially invasive interventions if misdiagnosed.

In this instance, early recognition of biochemical abnormalities prevented a false cancer diagnosis and allowed for curative surgery targeting the true source—the parathyroid tumor. Once removed, the body's natural healing mechanisms took over, enabling spontaneous fracture repair under proper supportive care.

Patient Education and Preventive Strategies

Following discharge, patients should be counseled on key lifestyle modifications to support ongoing bone health:

Dietary Adjustments: Emphasize calcium-rich foods such as dairy products, leafy greens, fortified plant-based milks, and small-boned fish like sardines.
Vitamin D Optimization: Encourage moderate sun exposure (15–20 minutes daily) and consider supplementation based on serum levels.
Regular Monitoring: Schedule periodic assessments of serum calcium, phosphate, PTH, and renal function. Neck ultrasound may help detect recurrence.
Bone Density Surveillance: Repeat DEXA scans every 1–2 years to monitor improvements in bone mineral density.

If delayed union or non-union of fractures occurs despite optimal care, surgical fixation may be considered. However, correcting the metabolic driver remains the cornerstone of successful rehabilitation.

Clinical Takeaways for Physicians

This case serves as a powerful reminder that unexplained bone pain and pathological fractures warrant comprehensive metabolic screening. Key lessons include:

Always assess calcium and PTH levels in patients presenting with osteolytic lesions or low-trauma fractures.
Do not assume malignancy without ruling out endocrine etiologies.
Early intervention in hyperparathyroidism can reverse skeletal damage and prevent future complications such as kidney stones or cardiovascular issues.
Interdisciplinary collaboration between endocrinology, radiology, and orthopedics enhances diagnostic accuracy and improves patient outcomes.

In conclusion, while metabolic bone disease may present with dramatic symptoms like fractures and severe pain, identifying and treating the root cause—such as a benign parathyroid adenoma—can lead to full functional recovery. Precision in diagnosis transforms what might seem like a devastating prognosis into a manageable and curable condition.