Masked primary (or tertiary) hyperparathyroidism.

Area of Science:

• Endocrinology
• Nephrology
• Gastroenterology

Background:

• Osteomalacia can be associated with gluten-sensitive enteropathy and anticonvulsant therapy.
• Hypercalcemia is a key indicator of hyperparathyroidism, but its interpretation can be complex.
• Tertiary hyperparathyroidism may present with masked or normocalcemic states.

Purpose of the Study:

• To describe two cases of osteomalacia that developed hypercalcemia post-treatment.
• To investigate the underlying cause of hypercalcemia in these patients.
• To explore the concept of masked tertiary hyperparathyroidism.

Main Methods:

• Clinical case presentation of two patients.
• Laboratory investigations including plasma calcium and 25-hydroxyvitamin D levels.
• Surgical exploration and histopathological examination for parathyroid tumors.

Main Results:

• Both patients initially presented with osteomalacia symptoms.
• Treatment for osteomalacia led to the development of hypercalcemia.
• Parathyroid tumors were identified in both patients, indicating tertiary hyperparathyroidism.

Conclusions:

• The study suggests that tertiary hyperparathyroidism can be masked by underlying conditions like osteomalacia.
• Normocalcemic hyperparathyroidism may be underdiagnosed due to masking effects.
• Accurate interpretation of plasma calcium requires consideration of 25-hydroxyvitamin D levels.