This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Adrenal Gland, Subject name: Medicine
[{'content': 'All of the following investigations are needed for evaluation of the given case except? \nSelect and explain. \nA. X ray wrist and elbow, B. Karyotype, C. Serum electrolytes, D. 24 hour urinary chloride', 'role': 'user'}, {'content': "Answer: D \nExplanation: The image shows clitoromegaly, labial fusion of a virilised female child. Inguinal folds don't exhibit any mass or swelling. The leading cause for this is congenital adrenal hyperplasia. Deficiency of 21-hydroxylase, resulting from mutations or deletions of CYP21A, is the most common form of CAH, accounting for more than 90% of cases. Choice A Useful for determining bone age which is advanced in CAH due to sex steroids Choice B Useful to identify CAH where a girl child has ambiguous genitalia Choice C Useful due to salt wasting and elevated potassium secondary to decreased aldosterone levels 24 hour urinary chloride is useful for renal tubular disorders like Bater syndrome and Gitelman syndrome.", 'role': 'assistant'}]