Purpose:​ To investigate the skeletal phenotype of adolescent girls with premature ovarian insufficiency (POI).

Methods:​ Data are presented from two adolescent girls who participated in a clinical research protocol to evaluate axial bone mineral density (BMD) (via dual-energy x-ray absorptiometry, DXA) and appendicular bone density, microarchitecture, and strength (via high-resolution peripheral quantitative computed tomography, HRpQCT). Anthropometric data were also obtained, and pubertal staging was performed by a clinician.

Results:​ Both cases presented with an undetectable estradiol concentration and an elevated follicle stimulating hormone (FSH), meeting the criteria for POI. Each also received alkylating agents as part of their chemotherapy and radiotherapy, but in different locations as one presented with stage IV neuroblastoma and the other, metastatic medulloblastoma. Both had a low BMD of the axial and appendicular skeleton, as well as microarchitectural changes of the latter. The low BMD Z-score (<−2.0) seen when interpreting their DXA measurements for chronological age improved when adjusted for short stature, but it was not normalized. Lastly, most variables obtained by HRpQCT were abnormal for each participant, indicating that appendicular bone structure and strength were compromised.

Conclusions:​ Chemotherapy and radiation affect growth, puberty, and bone accrual deleteriously. However, as these cases show, POI in an adolescent is not always classic primary ovarian insufficiency. Adolescents with brain cancer can present with signs of estrogen deficiency but may not be able to secrete FSH to the extent of elevation typically seen in long-term cancer survivors. Estrogen deficiency is almost universally present in either clinical setting and prompt recognition facilitates early provision of hormone replacement therapy that may then allow for a resumption of bone accrual as an adolescent approaches her peak bone mass.