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: Gynaecology & Obstetrics
[{'content': 'True about hCG :a) α subunit identical to LH, FSH and TSHb) Causes involution of corpus luteumc) Doubles in 7-10 daysd) Max. level seen at 60-70 days of gestatione) Detected in serum and urine 8-9 days after ovulation. \nSelect and explain. \nA. b, B. ad, C. ac, D. ab', 'role': 'user'}, {'content': 'Answer: B \nExplanation: hCG\n\nhCG is a glycoprotein\nIt is synthesized by syncytiotrophoblast of the placenta.\nhCG has 2 subunits :\n\n– α - biologically similar in LH, FSH and TSH. (i.e nonspecific)\n– β subunit - unique to hCG. (i.e specific)\n\nStructurally it is similar to - FSH, LH, TSH but functionally it is similar to LH ( i.e luteotropic), i.e. helps in maintaining corpus luteum. So, the main hormone which maintains activity of corpus luteum during pregnancy is hCG and in non pregnant state is LH.\nThe half life of hCG is 36 hours.\nIn early pregnancy the doubling time of hCG is 1.4-2 days.\nIt can be detected in maternal serum as early as 8 days following fertilisation/day 22 of menstrual cycle/5 days before missed period by immuno assay.\nThe level is 100 IU/L or mIU/mL around the time of the expected menses.\nThe levels progressively rise and reach maximum levels by about 8-10 weeks/70 days/1st trimester.\xa0It then falls until about 16 weeks and remains at low level up to term.\nhCG disappears from circulation by 2 weeks following delivery.\n\nAction:\n\nSustains the corpus luteum and thereby maintains the hormonal support to the pregnancy in early weeks.\nStimulates the Leydig cells of the male fetus to produce testosterone and thereby induces development of the male external genitalia.\nImmunosuppressive action which helps in the maintenance of pregnancy.\n\nNote: In 19, I have not included option ‘c’ as correct answer, i.e. detected in serum and urine 8-9 days after ovulation\nbecause it is detected in serum 8-9 days after ovulation but not in urine.\nExtra Edge:\nClinical implication of the measurement of hCG', 'role': 'assistant'}]