A 16-year-old boy is evaluated for gynaecomastia and failure to progress in school. Examination shows eunuchoid proportions with arm span exceeding height, small firm testes, and sparse facial hair. Semen analysis shows azoospermia. Serum testosterone is low, LH and FSH are markedly elevated. The most likely diagnosis is:
- A Androgen insensitivity syndrome
- B Klinefelter syndrome ✓
- C Kallmann syndrome
- D Constitutional delay of puberty
Correct answer: B. Klinefelter syndrome
Explanation
47,XXY (Klinefelter) causes primary testicular failure: hypergonadotropic hypogonadism with small firm testes, azoospermia, gynaecaecomastia, tall eunuchoid habitus, and learning difficulties. Elevated LH and FSH with low testosterone confirms gonadal failure. Androgen insensitivity gives a phenotypic female with absent uterus and normal male-range testosterone, while Kallmann syndrome shows LOW gonadotropins with anosmia, which excludes both distractors.
Reference: Williams Textbook of Endocrinology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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