A man presented with palpitations, headaches, profuse sweating and hypeension was suspected of having pheochromocytoma. The diagnostic procedure NOT done in case of pheochromocytoma is:
**Core Concept**
Pheochromocytoma is a rare, catecholamine-secreting tumor of the adrenal gland, leading to episodic hypertension, tachycardia, and other symptoms due to excessive release of epinephrine and norepinephrine.
**Why the Correct Answer is Right**
In pheochromocytoma, the primary concern is the sudden surge in catecholamine levels, which can lead to severe hypertension and cardiac complications. **Intravenous pyelography (IVP)** involves the use of a contrast agent that can cause a sudden increase in blood pressure, potentially triggering a hypertensive crisis in a patient with pheochromocytoma. This is because the contrast agent can stimulate the release of catecholamines from the tumor, exacerbating the condition.
**Why Each Wrong Option is Incorrect**
* **Option A:** MIBG (metaiodobenzylguanidine) scan is a safe and effective imaging modality for detecting pheochromocytomas, especially when other imaging modalities like CT or MRI are inconclusive.
* **Option B:** CT or MRI scans are commonly used for detecting pheochromocytomas, as they can provide detailed images of the adrenal glands and help locate the tumor.
* **Option D:** 24-hour urine collection for catecholamines is a useful diagnostic tool for pheochromocytoma, as it can help confirm the presence of excessive catecholamine levels in the urine.
**Clinical Pearl / High-Yield Fact**
When managing a patient suspected of having pheochromocytoma, it's essential to avoid any procedure that could potentially trigger a hypertensive crisis, such as the use of contrast agents or certain medications that can stimulate catecholamine release.
**Correct Answer:** A.