Differential Diagnosis for Recurrent Hyperparathyroidism

The patient's presentation with high parathyroid hormone and calcium levels after a left lower parathyroidectomy for primary hyperparathyroidism (adenoma) suggests a recurrence or persistence of the disease. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • B. Missed adenoma (< 6 months): This is the most common cause of recurrent hyperparathyroidism shortly after surgery. The presence of high parathyroid hormone and calcium levels just 4 months post-operatively strongly suggests that the initial adenoma was not fully removed or that another adenoma was missed during the surgery.

• Other Likely diagnoses

  • A. Parathyroid hyperplasia (>6 months recurrent): Although parathyroid hyperplasia is a common cause of primary hyperparathyroidism, it typically presents with a longer timeframe for recurrence after initial surgery. However, it cannot be ruled out, especially if the initial surgery did not address all affected glands.
  • C. New adenoma: The development of a new adenoma in the remaining parathyroid glands is possible but less likely than a missed adenoma, especially in the short term after surgery.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • D. Parathyroid cancer: Although rare, parathyroid cancer is a critical diagnosis not to miss due to its potential for severe consequences, including significant hypercalcemia and metastatic disease. The aggressive nature of parathyroid cancer necessitates its consideration in the differential diagnosis, despite its low likelihood.

• Rare diagnoses

  • Other rare causes, such as familial hyperparathyroidism syndromes (e.g., Multiple Endocrine Neoplasia type 1), could also be considered but are less likely given the context of a single adenoma initially treated. These conditions often have additional clinical features and family histories that would prompt their consideration.