How do kidneys help maintain bone health?

Most people know that the kidneys filter blood and make urine, but not everyone realizes they also play a vital role in keeping bones healthy. The kidneys help maintain bone strength by managing key minerals and activating vitamin D—both essential for strong, healthy bones.

One of the most important ways the kidneys support bone health is by activating vitamin D. The form of vitamin D you get from food or sunlight is inactive. Your kidneys convert it into its active form, known as calcitriol, which helps your body absorb calcium from the diet. Without enough active vitamin D, your body cannot absorb the calcium it needs, no matter how much you consume.

The kidneys also help regulate the levels of calcium and phosphorus in the blood. These minerals are crucial for building and maintaining bone tissue. When there is too much phosphorus or too little calcium, your body may take calcium from your bones to make up the difference, which can weaken them over time.

To prevent this, the kidneys excrete extra phosphorus through urine and help maintain the right balance of calcium. They also interact with a hormone called parathyroid hormone (PTH), which helps control calcium levels. If kidney function declines, this balance can be disrupted, leading to bone problems such as thinning or softening of the bones.

In short, your kidneys help keep your bones strong by regulating mineral levels and enabling your body to use vitamin D properly. This is why bone health and kidney health are closely linked—what affects one can often affect the other.

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