Sclerostin
What it means
Sclerostin is a protein made by bone cells called osteocytes that blocks new bone formation; less mechanical strain means more sclerostin, and more strain means less.
Sclerostin levels help determine whether your bone-building cells get switched on or held back, which matters for how your skeleton maintains itself over time.
Sclerostin is a protein made by osteocytes, the cells buried inside bone that sense mechanical signals. When an osteocyte doesn't detect enough strain, it produces sclerostin, which acts as a brake on bone formation by blocking osteoblasts from building new bone. When osteocytes do detect strain, sclerostin production goes down, releasing that brake.
This protein isn't just a normal regulator — it can also be hijacked. In multiple myeloma, a cancer of plasma cells in the bone marrow, cancer cells release sclerostin along with another protein called DKK1 to deliberately shut down osteoblasts. Combined with increased osteoclast activity from other signals the cancer produces, this leads to bone being broken down without being rebuilt, creating lytic lesions.
Sclerostin is also the target of a prescription medicine called romosozumab (Evenity), which works by blocking sclerostin's effect so bone formation can proceed. This makes it conceptually similar to what mechanical loading does in the body, though it works as a drug rather than through movement. Romosozumab is typically used for a limited time and carries a cardiovascular warning, so whether it's appropriate is a decision for your prescriber, not something to start or stop on your own.
How sure is this?
Graded Established Science: Supported by broad scientific consensus and decades of research. Read each study with its grade in mind. One study is a piece of the picture, not the whole of it.
Where the Academy teaches it
This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.
Questions people ask about this
Your bones actually have their own sensing system built right in. Buried deep inside bone tissue are cells called osteocytes — by far the most numerous cells in your skeleton — and their whole job is to detect mechanical force, like the kind created when you move, bear weight, or put strain through a bone.
Read the full answer →Pushing hard against a machine creates a strong, brief mechanical load on your skeleton. Your bones contain sensor cells that detect this load as fluid movement around them, and that signal tells bone-building cells to get to work, while slowing down the cells that break bone down. Over time, repeated signals like this are part of how bone tissue remodels itself.
Read the full answer →Osteoporosis generally can't be fully "reversed" back to young, healthy bone, but it can be meaningfully improved. The remodeling system that builds and removes bone is still working in osteoporosis — it's just shifted toward loss — so rebalancing it through loading, nutrition, hormones, and sometimes medication can help rebuild some density and strength over time.
Read the full answer →Related words
Osteocytes are the most common bone cells. They used to be bone-builders but got trapped inside bone tissue, where…
An osteoblast is a cell that builds new bone by laying down fresh bone matrix, working alongside cells that break…
The mechanostat is Frost's theory that bone acts like a thermostat, removing, maintaining, or building bone…
Romosozumab (brand name Evenity) is an anabolic osteoporosis medication given by injection that blocks sclerostin, a…
Multiple myeloma is a cancer of plasma cells in the bone marrow that disrupts the normal bone rebuilding process,…
Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.
