Recent research suggests that parathyroid hormone (PTH), a naturally occurring hormone, may hold the key to effectively treating chronic back pain by addressing its biological origins. A study conducted at Johns Hopkins University School of Medicine, published in the Journal of Bone Research, indicates that a treatment involving PTH could alleviate many forms of back pain.
PTH is produced by the parathyroid glands and plays a role in regulating calcium levels in the blood and influencing bone metabolism, capable of strengthening bone. Synthetic PTH has been used clinically to treat hypoparathyroidism and osteoporosis. Anecdotal reports from patients undergoing treatment with synthetic PTH for these conditions have noted an improvement in back pain, a benefit that remained unexplained until now.
In the study, mice were administered daily PTH injections for up to two months. High-resolution imaging of their spinal tissue, along with measurements of their movement and response to pressure, revealed significant findings. The mice treated with PTH exhibited increased density and stability in their vertebral endplates, the bone and cartilage layers separating spinal discs from vertebrae. These mice also demonstrated reduced sensitivity to pain, a greater tolerance to pressure, and increased activity levels.
Beyond enhancing bone density, PTH was observed to physically deter nerves from damaged spinal areas. This effect is achieved by stimulating osteoblasts, the bone-building cells, to release a protein called Slit3, which repels nerves. Dr. Janet Crane, the lead researcher, explained that in cases of spinal degeneration, pain-sensing nerves can grow into areas where they are not normally present. The study's findings indicate that PTH can reverse this process by activating natural signals that guide these nerves away from sensitive regions.
This mechanism suggests that PTH could effectively 'rewire' pain signals at their source, potentially offering a permanent reversal of the biological causes of chronic back pain, in contrast to treatments that only temporarily manage pain symptoms. Bob Chatterjee, a consultant spinal surgeon, described the discovery as exciting and a cause for optimism, noting that it builds upon existing knowledge.
Back pain can stem from various causes, including injury, congenital conditions like scoliosis, arthritis, and lifestyle factors such as prolonged sitting, smoking, or obesity. Mr. Chatterjee highlighted that this research specifically targets structural back pain, which involves the degeneration of spinal components like discs and joints. This degeneration can be a part of the aging process or result from abnormal spinal stresses due to poor posture or injury. Reports suggest that up to 40% of patients experience structural back pain, with a majority being over 50 years old. Therefore, for back pain originating from vertebral endplate degeneration, PTH may offer a beneficial approach by strengthening bone and repelling nerves from sensitive areas.
Similarly, the treatment might assist individuals whose symptoms arise from facet joint damage or arthritis, as joint damage can promote the growth of abnormal nerve endings. However, PTH treatment is likely to be less effective for back pain caused by muscle or ligament damage or solely by lifestyle factors.
Potential side effects of PTH treatment could impact calcium metabolism, potentially leading to nerve hyperexcitability symptoms like numbness and tingling if calcium levels decrease, or fatigue, brain fog, and mood disturbances if calcium levels increase excessively. Current treatments for back pain typically involve non-medical approaches like physiotherapy and osteopathy, pain medications, steroid injections, and, in severe cases, surgery. Mr. Chatterjee noted that these current methods often treat the effects of the problem rather than the root cause, whereas PTH therapy theoretically addresses the underlying issue.