'What can lie behind an osteoporosis diagnosis'?
Quite apart from whether osteoporosis is over- or under-diagnosed, there is another pertinent question. How often is the underlying cause of osteoporosis in the individual patient investigated?
My own experience suggests, “Not often enough.” I was diagnosed with osteopenia (BUA 63.9) in 2000, after suffering an agonising fracture through falling in the night on the way to the toilet. I was 57.
There were in fact four possible underlying causes for this.
First, I had been exposed to the organophosphate Malathion in my twenties.
Secondly, although I did not know it then, I had a parathyroid tumour which had been growing for at least six years.
Thirdly, although again, I did not know it at the time, I was almost certainly suffering from testosterone and growth hormone deficiency resulting from a bad head injury I sustained when I was 31.
Finally, I was in all probability B12 deficient for hereditary reasons.
I would now like to expand on these four factors and their relationship with osteoporosis.
A 1999 paper by Compston points out “Emerging evidence of premature osteoporotic change in people exposed to organophosphates means that a referral for bone density studies would seem to be an ethical part of any management plan, if these have not already been carried out. “  No management plan I had ever included this.
I was eventually diagnosed with a parathyroid tumour in 2006, that is, a full six years after my osteopenia diagnosis, by which time the tumour was at least twelve years old. The effect of a parathyroid tumour is to leach calcium from the bones. 
Severe traumatic brain injury very commonly results in hypopituitarism.  I was diagnosed as hypothyroid early on, but did not receive a diagnosis of growth hormone and testosterone deficiency until 2014. It is likely that I had been deficient in the latter two hormones throughout the twenty-six years since my head injury (1974), and both deficiencies are well documented to cause osteoporosis [4,5].
My mother was B12-deficient, so there was an inherent possibility that I might be too. Yet I was not diagnosed with this until 2005. This too has an association with osteoporosis. 
In short, my osteoporosis was a warning signal which could have led to the prompt diagnosis of the B12 deficiency, the hyperparathyroidism, and the hypopituitarism which had been undermining my health for so many years. Instead, I had to wait four, six and fourteen more years respectively for these diagnoses, years which were dogged by depression, weakness, weight gain and fatigue. What a wasted chance. Forty-one years is a long time to suffer from undiagnosed hypopituitarism.
I am 72 now, and at last receiving some benefit from replacement growth hormone and testosterone. I hope my story will help to save others from the catastrophic delay I suffered.
 Compston JE et al, reduced bone formation after exposure to organophosphates, Lancet 1999 Nov 20;354(9192):1791-2 http://www.ncbi.nlm.nih.gov/pubmed/10577647
 Editorials, Male Osteoporosis, Rheumatology 2000 39 1055-1059
“Any underlying secondary cause of osteoporosis should be treated if possible, as specific treatment of underlying conditions such as hyperthyroidism, hypogonadism and hyperparathyroidism may increase bone density by 10–20%.”
 Schneider HJ et al, Hypothalamopituitary Dysfunction following Traumatic Brain Injury and Aneurysmal Subarachnoid Haemorrage. A Systematic Review, 2007 JAMA http://jama.jamanetwork.com/article.aspx?articleid=208915
 Dupree K et al, Osteopenia and male hypogonadism, Rev Urol. 2004; 6(Suppl 6): S30–S34.
“Male hypogonadism is an important and treatable cause of osteoporosis. One of the primary treatment regimens for hypogonadism is testosterone replacement therapy, which helps not only to ameliorate the symptoms of hypogonadism, but to increase bone mineral density (BMD) as well.” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472878/
 Society for Endocrinology, You and your hormones http://www.yourhormones.info/endocrine_conditions/adult_growth_hormone_d...
 Tucker K et al, Low Plasma Vitamin B12 is Associated With Lower BMD: The Framingham Osteoporosis Study, 2005, Journal of Bone and Mineral Research Vol 20, 152-158,
Competing interests: No competing interests