<prompt> Peak HCG levels are seen by what intrauterine age?8-10 weeks11-13 weeks20 weeks25 weeks  <response>: ANSWER: A 8-10 weeksREF: Dutta 6th ed p. 58.59f Current OBGYN 10th ed chapter 8, Williams 22th ed chapter 3Repeat from Primary DNB CET December 2011HUMAN CHORIONIC GONADOTROPHIN: hCG is a glycoprotein composed of 2 subunits, alpha and beta. The alpha subunit is common to all glycoproteins, and the beta subunit confers unique specificity to the hormone. Typically, neither subunit is active by itself; only the intact molecule exerts hormonal effects. Synthesized by syncytiotrophoblasts of the placenta Half life is 32-37 hours, in contrast to that of most protein and steroid hormones, which have half-lives measured in minutes. which have half-lives measured in minutes. In early pregnancy doubling time is 2 days Can be detected as early as 9 days after the midcycle LH peak, which occurs 8 days after ovulation and only 1 day after implantation. The hCG level above which one should identify an embryo by transvaginal ultrasonography TVU is now 1,000 to 2,000 mlUmL, as determined by the second international standard. Levels progressively rise and reach maximum by 8-10 weeks60-80 days 1st trimester Falls until 18-20 weeks and remains low until term. Disappears from circulation by 2 weeksWeeks of Gestation 