From the Guidelines
In a patient with hypercalcemia and a ureteral stone, a comprehensive workup for primary hyperparathyroidism should be ordered next, in addition to treating the stone, and this should include ordering a Parathyroid hormone (PTH) level. This approach is based on the understanding that primary hyperparathyroidism is a significant cause of hypercalcemia and can lead to kidney stone formation due to increased urinary calcium excretion 1. The association between hypercalcemia and kidney stones is well-documented, with approximately 20% of patients with primary hyperparathyroidism developing kidney stones. Key considerations in the workup and management include:
- Evaluating serum parathyroid hormone (PTH) levels to diagnose primary hyperparathyroidism
- Assessing 24-hour urine calcium excretion to understand the impact on stone formation
- Measuring serum phosphorus and vitamin D levels for a comprehensive metabolic evaluation
- Referral to an endocrinologist and possibly a parathyroid surgeon if primary hyperparathyroidism is confirmed Other causes of hypercalcemia, such as malignancy, granulomatous diseases, and medication effects, should also be considered but are less common in outpatients with kidney stones and hypercalcemia compared to primary hyperparathyroidism 1. Given the potential for recurrent stone formation if the underlying hypercalcemia is not addressed, prioritizing the diagnosis and treatment of primary hyperparathyroidism is crucial 1.
From the Research
Next Steps in Diagnosis
In a patient with hypercalcemia and a ureteral stone, the following steps should be considered:
- The most common cause of hypercalcemia is primary hyperparathyroidism, so assessing the level of parathyroid hormone (PTH) is crucial 2
- Other basic investigations include plasma phosphorus level, vitamin D, and calculated creatinine clearance 2
Diagnostic Considerations
When evaluating hypercalcemia, it is essential to consider the following:
- PTH-dependent hypercalcemia is mainly caused by primary hyperparathyreosis 2
- If PTH is suppressed, malignant disease must be considered carefully 2
- The diagnosis of primary hyperparathyroidism (PHPT) is confirmed in the presence of hypercalcemia and a normal or elevated PTH level in the absence of conditions that mimic PHPT 3
Laboratory Tests
The following laboratory tests may be ordered:
- Parathyroid hormone (PTH) level to assess for primary hyperparathyroidism 2, 3
- Serum calcium and phosphorus levels to evaluate the severity of hypercalcemia
- Vitamin D level to assess for vitamin D-mediated hypercalcemia 4, 5
- 1,25-Dihydroxyvitamin D level to evaluate for vitamin D-mediated hypercalcemia 5
Answer
Based on the provided evidence, the most appropriate next step would be to order: A. Parathyroid hormone (PTH) level to assess for primary hyperparathyroidism, as it is the most common cause of hypercalcemia 2, 3