UNEXPLAINED BONE LOSS FOLLOWING DEPO-PROVERA
QUESTION--I had a 36 year old african american female referred to me for an abnormal TSH 0.29. She has a family history of graves disease but she has never been diagnosed with hyperthyroidism. While looking through her records I came across a DXA scan which was recently done and showed Z-score -2.2 in femoral neck, -0.6 in lumbar spine and I had radiology look at it again and make sure it was accurate. while talking with her, She had another DXA done 10 years prior because she had been on depo-provera for about 8 or 9 years while in her late teens until about 26 when the original DXA was done. Unfortunately it was done at another institution and only read with T-scores and I do not have the original images to review. She was then switched to an estrogen containing oral contraceptive. No history of bone fractures, no family history of bone fractures. no other complaints noted.
I did an investigation for secondary cause of her low bone mineral density for her age: CBC normal, CMP normal, phosphorus normal, magnessium normal, celaic panel negative, 24 urine calcium normal, PTH normal, repeat TSH normal and negative TSI, vitamin D 25 was only mild low at 24. I diagnosed her with low bone mineral density for her chronological age.
I know Depo-provera can cause reductions in BMD but this is usually reversible when the medication is stopped and she was also placed on an estrogen containing OCP afterwards. She has been on calcium and vitamin D supplements as well as resistance exercise for years and I am concerned about her bone mineral density. I am wondering if I should continue to look for another cause of her low bone mineral density or consider medical treatment with a bisphosphonate possibly. JONATHAN.SLUSSER@GMAIL.COM
R5ESPONSE-Cessation of long-term depo-progesterone therapy can be followed by recovery of bone loss, but this may be incomplete. You have done an excellent evaluation for factors contributing to BMD less than expected for age. If she has had no fractures and there are no other clinical concerns, this may be enough. If you are worried that she might continue to lose bone, you might want to check a bone resorption marker, such as CTX or NTX. A high value would suggest a high rate of bone remodeling and ongoing bone loss. If that is the case, more aggressive evaluation and treatment could be considered. E.MICHAEL LEWIECKI, MD