The Women’s Health Nurse Practitioner evaluated Sara, a 17-yearold female. Sara has not had a menstrual period for 6 months. Herhistory reveals that menarche occurred at the age of 12 years, andher menses were regular at 28-day intervals until they becameirregular 1 year ago. Sara is a member of her high schoolgymnastics team. She has been spending long hours training with theteam, as she hopes to get a gymnastic scholarship at her “dreamâ€university – the University of California, Los Angeles. Inaddition, she has ramped up her aerobic exercise program tostrengthen her endurance. She states that she often does not havetime to eat or is simply too tired to eat after training andgetting her schoolwork done. She often relies on energy bars. Shedenies abdominal pain or bloating. Sara appears emaciated. She is 5ft 4 in tall and weighs 88 lb; BMI is 15 kg/m2. Her pulse is54/min, and blood pressure is 80/50 mm Hg. The rest of her physicalexam is non-remarkable. Impression - The Nurse Practitionersuspects secondary amenorrhea(i.e., the absence of 3 to 12consecutive menstrual periods after menarche). The secondaryamenorrhea is most likely due to her exercise program, which hasincreased in intensity and duration over the last 6 months. It isalso possible that Sara is not eating enough, given her high energyexpenditure. To determine the cause of her amenorrhea, laboratorytests are ordered. Laboratory Test Results Pregnancy test negativeLH Below normal FSH Below normal Estradiol Below normal Serum totalcalcium 7.8 mg/dl (normal range = 8.6-10.3 mg/dl) Serum ionizedcalcium 3.9 mg/dl (normal range = 4.4-5.2 mg/dl) Serum vitamin D,25 hydroxy 25 ng/ml (normal range = 30-80 ng/ml) Serum PTHIncreased above normal Follow Up Tests: Given that Sara’s serumcalcium and vitamin D results were below normal, Sara had a bonedensity (DXA scan). Results revealed a Z score = -1 (lower thannormal bone density). Given the low LH and FSH, Sara was testedwith a priming dose of intravenous pulsatile GnRH (1-2 mg/90minutes). Results showed normal levels of LH and FSH, in responseto GnRH.
1. Considering Sara’s level of PTH, describe what adaptiveresponse might be taking place within Sara’s bone (i.e., focus onthe inter-relationship between the cells within the osteon)? Howdoes this relate to her bone density results?
