A 30-year-old female presents with new onset hypertension. Which lab test could help rule out pheochromocytoma?

The most effective lab test for ruling out pheochromocytoma is a 24-hour urine metanephrines test. Pheochromocytoma is a rare tumor of the adrenal gland that secretes catecholamines, leading to symptoms such as hypertension, palpitations, and diaphoresis. Metanephrines are the metabolites of catecholamines, and their presence in urine is a strong indicator of catecholamine-secreting tumors.

By measuring the levels of metanephrines over a 24-hour period, this test provides a comprehensive assessment of catecholamine production and helps confirm or exclude the diagnosis of pheochromocytoma. If the metanephrine levels are normal, it effectively rules out the presence of a pheochromocytoma.

In contrast, the other choices do not provide relevant information for diagnosing or ruling out pheochromocytoma. A complete blood count primarily assesses general health and screens for various conditions but is not specific to adrenal tumors. A lipid panel evaluates cholesterol and triglyceride levels, which are not directly related to pheochromocytoma. Thyroid function tests assess thyroid hormone levels and can help identify thyroid-related issues that might lead to hypertension, but they do not provide insight into cate