A -year-old woman comes to the clinic for a routine wellness examination. She reports feeling generally well, though she has experienced mild fatigue and occasional constipation over the past few months. She takes no medications and has no significant past medical history. Vital signs are within normal limits. Laboratory studies show:
| Laboratory Test | Result | Reference Range |
|---|---|---|
| Calcium, serum | mg/dL | mg/dL |
| Phosphorus, serum | mg/dL | mg/dL |
| Albumin, serum | g/dL | g/dL |
| Creatinine, serum | mg/dL | mg/dL |
| Intact parathyroid hormone | pg/mL | pg/mL |
Which of the following is the most likely diagnosis based on these laboratory findings?
- Primary hyperparathyroidismCevap
- BSecondary hyperparathyroidism
- CHypercalcemia of malignancy
- DVitamin D toxicity
- ETertiary hyperparathyroidism
Cevap
Primary hyperparathyroidism is the correct diagnosis.
The correct answer is primary hyperparathyroidism. The diagnostic algorithm for hypercalcemia begins with measuring intact parathyroid hormone (PTH). In a normal physiological state, high serum calcium strongly suppresses PTH secretion. Therefore, an elevated or even high-normal (inappropriately unsuppressed) PTH level in the presence of hypercalcemia defines PTH-dependent hypercalcemia. Given the patient's normal renal function (normal creatinine) and characteristic hypophosphatemia (PTH promotes renal phosphate excretion), primary hyperparathyroidism is the definitive diagnosis. Most cases are caused by a single benign parathyroid adenoma.
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Anahtar Kavram
The diagnosis of primary hyperparathyroidism is established by finding hypercalcemia with an inappropriately elevated or unsuppressed intact parathyroid hormone (PTH) level, typically accompanied by hypophosphatemia.
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