Among postmenopausal women who received an epidural steroid injection (ESI) in the lumbar spine to treat back and leg pain arising from a compressed nerve in the spine, levels of bone formation biomarkers were decreased. The decrease in levels persisted more than 12 weeks, results from a new study show.
In addition, serum cortisol levels decreased by 50% at week 1 after the ESI, indicating systemic absorption of the steroid.
“The extent and duration of these effects suggest that patients who receive multiple [ESIs in the lumbar spine] may be at particular risk for harmful skeletal consequences,” Shannon Clare reported in an oral presentation at the annual meeting of the American Society for Bone and Mineral Research.
Further studies are needed of the relationship between these short-term changes in bone turnover and bone loss and the risk for fracture among the burgeoning population treated with ESIs, added Ms. Clare, of the Hospital for Special Surgery, New York.
The researchers examined changes in serum levels of bone formation and resorption markers and other analytes in 24 women who received a lumbar ESI for radicular back pain and in 8 other women from the hospital population who served as control persons.
Among the women who received ESI, 1 week after the injection, serum levels of two bone formation biomarkers – total procollagen type 1 N-terminal peptide (P1NP) and osteocalcin – were about 27% lower than at baseline. The suppression persisted beyond 12 weeks.
Serum levels of the bone resorption biomarker C-terminal telopeptide of type I collagen (CTX) did not differ significantly after ESI.
“Our results are notable because we found that the duration of suppression of bone formation extended beyond 12 weeks, a far longer duration than seen previously with intra-articular injections” of glucocorticoids, said Ms. Clare and senior author Emily M. Stein, MD, director of research for the Metabolic Bone Service and an endocrinologist at the Hospital for Special Surgery and is associate professor of medicine at Weill Cornell Medicine, both in New York.
The findings suggest that patients should not receive multiple doses within a 12-week period, they told this news organization in a joint email response.
Women are not typically screened for osteopenia or osteoporosis before ESI. However, “our results suggest that physicians should consider screening women for osteoporosis who receive ESI, particularly those who are treated with multiple doses,” said Ms. Clare and Dr. Stein. “Steroid exposure should be minimized as much as possible by having patients space injections as far as they can tolerate.”
Systemic absorption, negative impact on bone turnover markers
“The hypothesis that [ESIs] interfere with the vertebral osseous microenvironment and increase the risk of vertebral fractures has been supported with evidence in the literature,” Mohamad Bydon, MD, professor of neurosurgery, orthopedic surgery, and health services research at the Mayo Clinic, Rochester, Minn., said in an interview.
Prior studies have demonstrated a decrease in bone mineral density (BMD) and an increase in vertebral fractures following ESI, added Dr. Bydon, senior author of a 2018 review of the effect of ESI on BMD and vertebral fracture risk that was published in Pain Medicine. He was not involved with the current study.
“The article by Clare et al. provides evidence on the systemic absorption of glucocorticoids by demonstrating a drop in serum cortisol following ESI,” he noted. “The measurement of bone metabolism biomarkers offers molecular confirmation of clinical and radiological observations of previous studies” showing that ESI affects the vertebrae.