Incidental Normocalcemic Primary Hyperparathyroidism Presenting With Symptomatic Hypophosphatemia: A Case Report

Area of Science:

• Endocrinology
• Biochemistry

Background:

• Normocalcemic primary hyperparathyroidism (NHPT) is a recently defined subtype of primary hyperparathyroidism (PHPT).
• NHPT diagnosis requires persistently normal calcium levels with elevated parathyroid hormone (PTH) and exclusion of secondary causes.
• Surgical management consensus for NHPT mirrors that of PHPT, though NHPT is less understood.

Observation:

• This report details a rare instance of incidentally discovered NHPT.
• The patient presented with symptomatic hypophosphatemia, a condition not typically associated with NHPT diagnosis or management guidelines.
• Serum phosphate levels are not considered in the diagnostic criteria for PHPT or NHPT.

Findings:

• The patient with NHPT exhibited hypophosphatemia, challenging typical clinical presentations.
• Surgical intervention was pursued despite the atypical presentation and lack of phosphate level guidance in current guidelines.
• This case underscores the variability in NHPT manifestations.

Implications:

• The findings suggest that symptomatic hypophosphatemia can occur in NHPT, necessitating further investigation.
• This case may prompt a re-evaluation of diagnostic and management strategies for NHPT, particularly regarding phosphate levels.
• Further research is needed to clarify the role of phosphate in NHPT pathophysiology and treatment decisions.