A 21-year-old woman comes to the physician for evaluation of excess hair growth on her face. Menses occur irregularly at 45 to 65-day intervals. She is 159 cm (5 ft 3 in) tall and weighs 59 kg (130 lb); BMI is 23 kg/m2. Physical examination shows facial acne and growth of coarse dark hair on the face, chest, and lower back. Pelvic examination shows no abnormalities. Ultrasound examination of the pelvis reveals a normal uterus and ovaries. Electrolytes are normal; other laboratory results are as follows: Which of the following enzyme reaction steps is most likely to be disrupted in this patient?

Question

A 21-year-old woman comes to the physician for evaluation of excess hair growth on her face. Menses occur irregularly at 45 to 65-day intervals. She is 159 cm (5 ft 3 in) tall and weighs 59 kg (130 lb); BMI is 23 kg/m2. Physical examination shows facial acne and growth of coarse dark hair on the face, chest, and lower back. Pelvic examination shows no abnormalities. Ultrasound examination of the pelvis reveals a normal uterus and ovaries.  Electrolytes are normal; other laboratory results are as follows:  Which of the following enzyme reaction steps is most likely to be disrupted in this patient?

Quizplus · Accepted Answer

Eductional Objective: Nonclassic congenital adrenal hyperplasia is due to mild deficiency of 21-hydroxylase, an enzyme that converts progesterone to 11-deoxycorticosterone and 17-hydroxyprogesterone to 11-deoxycortisol.  In adolescent girls, it presents with signs of hyperandrogenism (eg, hirsutism, acne, menstrual irregularities) as well as increased 17-hydroxyprogesterone and testosterone levels.

A 21-Year-Old Woman Comes to the Physician for Evaluation of Excess