Differential Diagnosis for Hypercalcemia and Elevated PTH in a 65-year-old Female
Single Most Likely Diagnosis
- Primary Hyperparathyroidism: This condition is characterized by an overproduction of parathyroid hormone (PTH), leading to hypercalcemia. The patient's elevated PTH level (116) and high calcium level (11.1) are consistent with this diagnosis. Primary hyperparathyroidism is a common cause of hypercalcemia in adults, especially in postmenopausal women.
Other Likely Diagnoses
- Familial Hypocalciuric Hypercalcemia (FHH): Although less common, FHH is another condition that can cause elevated PTH and calcium levels. It is an inherited disorder that affects the calcium-sensing receptor, leading to inappropriate PTH secretion.
- Lithium-Induced Hyperparathyroidism: Long-term lithium therapy can cause hyperparathyroidism, leading to elevated PTH and calcium levels. However, there is no mention of lithium use in the patient's history.
- Vitamin D Intoxication: Excessive intake of vitamin D can lead to hypercalcemia, but PTH levels are usually suppressed in this condition.
Do Not Miss Diagnoses
- Malignancy-Associated Hypercalcemia: Certain types of cancer, such as parathyroid hormone-related protein (PTHrP)-producing tumors, can cause hypercalcemia and elevated PTH levels. Although less likely, it is crucial to rule out malignancy due to its severe consequences.
- Hypercalcemia of Malignancy with PTHrP: Some cancers, like squamous cell lung cancer, can produce PTHrP, leading to hypercalcemia and elevated PTH levels.
Rare Diagnoses
- Multiple Endocrine Neoplasia (MEN) Syndromes: These rare genetic disorders can cause hyperparathyroidism, leading to elevated PTH and calcium levels.
- Parathyroid Carcinoma: A rare cause of primary hyperparathyroidism, parathyroid carcinoma can lead to severely elevated PTH and calcium levels.
- Teriparatide (PTH analogue) Therapy: Although unlikely, teriparatide therapy can cause elevated PTH and calcium levels, but this would be a known medication side effect.