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How can low vitamin D levels contribute to rickets and osteomalacia?

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bone disease Defect of tibia, caused by septic osteomyelitis in childhood, with compensatory thickening of the fibula (right). Normal bones are shown at left.

Low vitamin D levels contribute to rickets and osteomalacia by impairing the body's ability to maintain bone rigidity through proper mineralization.12

Vitamin D, specifically in its active form known as calcitriol, is essential for the efficient absorption of calcium and phosphate in the small intestine. When vitamin D is deficient, these minerals are not absorbed effectively, leading to low serum concentrations.12

In response to low serum calcium, the parathyroid glands secrete parathormone, which mobilizes calcium from the bones to restore blood levels. While the body continues to produce the protein matrix (osteoid) of the bone, the lack of available calcium and phosphate prevents this matrix from being properly calcified. This results in soft, weak bones—a condition termed rickets in children and osteomalacia in adults. In children, this process also leads to abnormal bone growth and cartilage overgrowth.1234