Up to 70pc of those at very high risk of bone fracture are not being treated adequately, researchers at the University of Galway show.
They warned that a major gap has emerged between needless overtreatment on the one hand and undertreatment on the other.
Between 300,000 and 500,000 people have osteoporosis, which leaves bones at greater risk of breaking, and it is a leading cause of patients ending up in emergency departments.
John Carey, professor in medicine at University of Galway who diagnoses and treats people with osteoporosis, said calcium and vitamin D were being prescribed for the condition, but he insisted they were not a treatment.
Calcium and vitamin D prescribing outstrips osteoporosis medication prescribing, despite costing around the same.
Calcium and vitamin D are essential for good bone health, but are only a treatment for those who are low in both or have osteomalacia, where someone has soft bones.
It has knock-on effects. They are put on treatment and they are ending up with complications and significant harm.
He said that osteoporosis medications were treatments and there was strong evidence to support their use at a cost of €100-€300 a year.
The research looked at more than 5,000 men and women referred to the Galway University Hospital osteoporosis service and showed 70pc of women and 54pc of men at very high risk of fracture are not on treatment.
Prof Carey, who is clinical lead in DXA, Osteoporosis and Fracture Liaison Services, said poor quality DXA scans – which measure bone mineral density – in some centres were leading to “false positives” with younger people wrongly diagnosed.
This is leading to over-prescribing in young people, he added.
“You cannot diagnose osteoporosis on the basis of a DXA scan alone. It is more complicated. There are false positives and it is linked to lack of training.”
He added that “women and men in 30s, 40s and 50s are getting DXA scans, which are sometimes of very poor quality.
“It has knock-on effects. They are put on treatment and they are ending up with complications and significant harm.
“On the other hand, we regularly see patients who have had a fracture and sometimes low or very low bone mineral density who are not treated, despite multiple recommendations and overwhelming evidence that this is the group of people mostly likely to benefit from treatment.”
Prof Carey sees a few people a week who had broken a bone and been to the emergency department or doctor had been told they had a spasm.
“This can go on for months or for years,” he added.
There was a need for more DXA scanners in public hospitals with services in Portiuncula Hospital, Letterkenny Hospital and Cork University Hospital closed while people were being referred to private centres instead, said Prof Carey.
He called for a national programme to end what he described as the “chaotic” current system.
