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: Pathology
[{'content': 'A male patient 56 year old complains of swelling in legs. He is a known case of hypertension and is under treatment. On general physical examination pitting oedema is seen on legs and TSH level 3mU/L. Which of the following is not a cause of this condition? \nSelect and explain. \nA. Increase in hydrostatic pressure, B. Decreased colloid osmotic pressure, C. Due to lymphatic obstruction, D. Myxedema', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Most leg swelling is caused by oedema, the accumulation of ﬂuid within the interstitial space. Unilateral swelling usually indicates a localised pathology in either the venous or the lymphatic system, while bilateral oedema often represents generalised ﬂuid overload combined with the effects of gravity. However, all causes of unilateral leg swelling may present bilaterally, and generalised ﬂuid overload may present with asymmetrical (and therefore apparently unilateral) oedema. Fluid overload may be the result of cardiac failure, pulmonary hypertension (even in the absence of right ventricular failure), renal failure, hypoalbuminaemia or drugs (calcium channel blockers, glucocorticoids, mineralocorticoids, non-steroidal anti-inﬂammatory drugs (NSAIDs) and others).\n\xa0Approximately\xa060%\xa0of\xa0lean\xa0body\xa0weight\xa0is\xa0water,\xa0two-thirds\xa0of\xa0which\xa0is\xa0intracellular.\xa0Most\xa0of\xa0the\xa0remaining water is found in extracellular compartments in the form of interstitial fluid; only 5% of the body’s water is in blood\xa0plasma.\xa0As\xa0noted\xa0earlier,\xa0edema\xa0is\xa0an\xa0accumulation\xa0of interstitial fluid within tissues.\xa0\n\nIncrease in hydrostatic pressure are mainly caused by disorders that impair venous return. Local increases in intravascular pressure caused, for example, by deep venous thrombosis in the lower extremity can cause edema restricted to the distal portion of the affected leg.\nReduction of plasma albumin concentrations leads to decreased colloidal osmotic pressure of the blood and loss of fluid from the circulation.\nEdema may result from lymphatic obstruction that compromises resorption of fluid from interstitial spaces.\n\n\xa0\nReference:Davidson’s Internal Medicine 23rd edition, page no.186', 'role': 'assistant'}]