Hyperparathyroidism (HPTH) is the third most common endocrine disorder. Hypovitaminosis D affects up to 40% of the general population and about a third of hyperparathyroid patients. Such a combination may alter the classic presentation of HPTH. This report presents a premenopausal female with long history of osteoporosis, normocalcemia, and hypovitaminosis D who was initially diagnosed as secondary HPTH. After restoring vitamin D to normal using parenteral loading doses, the patient developed persistent mild to moderate hypercalcemia with persistent parathormone elevation consistent with primary HPTH associated with hypercalciuria and complicated with nephrocalcinosis. Imaging confirmed a left upper parathyroid adenoma and fulfilling several indications for surgery, the patient was operated restoring normocalcemia that was maintained for several years of follow-up. Hypovitaminosis D is common and may mask expected hypercalcemia in patients with primary HPTH, thus delaying diagnosis and proper intervention. Reevaluating patients initially diagnosed as hypovitaminosis D and secondary HPTH may reveal a masked diagnosis of primary hyperparathyroidism.

中文翻译：

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维生素 D 缺乏症掩盖原发性甲状旁腺功能亢进症的高钙血症：病例报告。

甲状旁腺功能亢进症 (HPTH) 是第三大常见的内分泌疾病。维生素 D 缺乏症影响高达 40% 的普通人群和约三分之一的甲状旁腺功能亢进患者。这种组合可能会改变 HPTH 的经典表现。本报告介绍了一位患有长期骨质疏松症、正常钙血症和维生素 D 缺乏症病史的绝经前女性，最初被诊断为继发性 HPTH。使用肠外负荷剂量将维生素 D 恢复至正常后，患者出现持续性轻度至中度高钙血症，并伴有持续性甲状旁腺激素升高，这与原发性 HPTH 相关，伴有高钙尿症并并发肾钙质沉着症。影像学检查证实患者患有左上甲状旁腺腺瘤，并满足多项手术指征，手术后患者血钙恢复正常，并在随访数年中维持正常。维生素 D 缺乏症很常见，可能会掩盖原发性 HPTH 患者预期的高钙血症，从而延误诊断和适当的干预。重新评估最初诊断为维生素 D 缺乏症和继发性 HPTH 的患者可能会发现原发性甲状旁腺功能亢进症的隐蔽诊断。