Normocalcemic primary hyperparathyroidism.

Area of Science:

• Endocrinology
• Metabolic Bone Disease

Background:

• Normocalcemic primary hyperparathyroidism (PHPT) is a distinct clinical presentation of PHPT.
• Characterized by elevated parathyroid hormone (PTH) levels with normal serum calcium.
• Increasingly diagnosed during investigations for kidney stones or metabolic bone disorders.

Purpose of the Study:

• To review the diagnostic criteria, epidemiology, and clinical presentation of normocalcemic PHPT.
• To discuss the current understanding of its natural history and management.
• To highlight the importance of accurate diagnosis and cautious surgical recommendations.

Main Methods:

• Diagnosis by exclusion of secondary hyperparathyroidism (e.g., vitamin D deficiency, renal failure).
• Requires consistent elevation of PTH and measurement of ionized calcium.
• Review of existing literature on diagnostic features, epidemiology, and clinical presentation.

Main Results:

• Normocalcemic PHPT is diagnosed when PTH is high and calcium is normal, after ruling out other causes.
• Potential for bone and renal complications, though rates vary due to diagnostic challenges.
• Lack of standardized diagnostic criteria and potential selection bias in studies.

Conclusions:

• Normocalcemic PHPT requires careful diagnosis, excluding secondary causes and confirming persistent high PTH.
• The natural history and long-term outcomes are not fully understood.
• Surgical intervention should be considered cautiously and only when clearly indicated.