<prompt> A 15-year-old girl co failure to attain menarche. Her height is 4 feet. She has not yet developed secondary sexual characteristics. If USG shows uterus and vagina. FSH and LH levels are high. What is the best step in confirming the diagnosis?Perform a CTPerform a KaryotypePerform a buccal smearPerform progesterone withdrawal test  <response>: Ans. is b, i.e. Perform a karyotype1st step in primary amenorrhea is to identify the site of lesion by doing Hormonal profileIn question : LH and FSH are highUSG: shows uterus and vagina are presentPt has short height 4 feetNo secondary sexual characteristicsNow since LH and FSH are high and estrogen is low as secondary sexual characteristics are absent? It is a case of hypergonadotropic hypogonadism --so most probably it is Turners syndrome. This can be confirmed by doing karyotyping.Always remember in Primary amenorrhea1st Test: Hormonal ProfileBest Test: Karyotyping 