This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': "A 30 year old female presents with bluish black discoloration of sclera and pinna for last 4 months. Her urine turns black on standing. Which of the following tests is not used for diagnosis of this condition? \nSelect and explain. \nA. Benedict's test, B. Ferric chloride test, C. Silver nitrate test, D. Guthrie test", 'role': 'user'}, {'content': "Answer: D \nExplanation: Clinical Presentation of Alkaptonuria:\n\nNormal life till 3rd or 4th decade\nUrine darkens\xa0on standing is the only manifestation in children.\nIn adults, ochronosis, i.e. Alkaptone body deposition\xa0in intervertebral disk, cartilage of nose, pinna, etc. leading to pigmentation.\nArthritis.\nNo mental retardation.\n\nLaboratory Diagnosis:\n\nAlkalinization increases the darkening of urine.\nBenedict's test positive in urine because homogentisic acid is a reducing agent.\nFerric chloride test positive.\nSilver nitrate test positive.\n\nNote:\xa0Guthrie bacterial inhibition test is a screening test for phenylketonuria.\nReference- Harper’s illustrated biochemistry. 30th edition page -304", 'role': 'assistant'}]