Endocrine Pathology, Pathology, USMLE Step 1 - Full Vignette with Extended Explanations скачать в хорошем качестве

Endocrine Pathology, Pathology, USMLE Step 1 - Full Vignette with Extended Explanations

A 3-year-old girl experiences six weeks of episodic irritability, pallor, sweating, and severe headaches, with each episode ending in profound fatigue and normal behavior between spells. She now presents with severe, intermittent hypertension, a complex family history, and unremarkable prior workup. In this challenging clinical scenario, what should guide your next diagnostic steps when faced with paroxysmal symptoms and persistently unexplained findings in a young child? VIDEO INFO Category: Endocrine Pathology, Pathology, USMLE Step 1 Difficulty: Hard - Advanced level - Challenges experienced practitioners Question Type: Diagnostic Failure Case Type: ED Case Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h... QUESTION A 3-year-old girl is brought to a regional emergency department for episodic irritability, pallor, sweating, and headaches over six weeks. Parents note that during some episodes her face becomes pale and sweaty, she clutches her head, and she wants the room dark. The spells last about 10-20 minutes and end with profound fatigue. Between episodes she plays normally. She has no known drug allergies.... OPTIONS A. Measure plasma free metanephrines by LC-MS/MS drawn with the child supine after at least 20-30 minutes of quiet rest, using pediatric reference intervals; proceed to imaging only if results are positive. B. Obtain seated random plasma catecholamines without rest and send the child directly to same-day CT of chest/abdomen/pelvis if any value is borderline elevated. C. Order a 24-hour urinary vanillylmandelic acid collection alone because it is simpler than metanephrines and sufficient to exclude catecholamine-secreting tumors in children. D. Schedule immediate MIBG scintigraphy before any biochemical testing to avoid missing extra-adrenal paragangliomas that may secrete catecholamines intermittently. CORRECT ANSWER A. Measure plasma free metanephrines by LC-MS/MS drawn with the child supine after at least 20-30 minutes of quiet rest, using pediatric reference intervals; proceed to imaging only if results are positive. EXPLANATION This child has paroxysmal headaches, pallor, diaphoresis, and documented severe episodic hypertension with a family history of SDHB-related paraganglioma, strongly suggesting a catecholamine-producing tumor. Per the Endocrine Society guideline, biochemical confirmation should precede imaging, and preanalytical conditions critically affect false-positive rates, especially in children. The most sensitive and appropriate initial test is plasma free metanephrines by LC-MS/MS obtained with the child supine after at least 20-30 minutes of quiet rest, interpreted using pediatric reference intervals. Positive results then direct targeted imaging. Random seated catecholamines without rest are prone to false positives; immediate CT based on borderline values risks unnecessary radiation. A 24-hour urinary VMA alone is less sensitive than metanephrines and can miss tumors, particularly extra-adrenal lesions. MIBG scintigraphy is not a first-line diagnostic study and should follow biochemical confirmation and cross-sectional imaging if indicated.... --------------------------------------------------- Our cases and questions come from the https://EndlessMedical.Academy quiz engine - multi-model platform. Each question and explanation is forged by consensus between multiple top AI models (GPT, Claude, Grok, etc.), with automated web searches for the latest research and verified references. Calculations (e.g. eGFR, dosages) are checked via code execution to eliminate errors, and all references are reviewed by several AIs to minimize hallucinations. Important note: This material is entirely AI-generated and has not been verified by human experts; despite stringent consensus checks, perfect accuracy cannot be guaranteed. Exercise caution - always corroborate the content with trusted references or qualified professionals, and never apply information from this book to patient care or clinical decisions without independent verification. Clinicians already rely on AI and online tools - myself included - so treat this book as an additional focused aid, not a replacement for proper medical education. Visit https://endlessmedical.academy for more AI-supported resources and cases. This material can not be treated as medical advice. May contain errors. ---------------------------------------------------