11 Essential Bone Health Facts About Calcium and Vitamin D You Should Know

7. How to recognize deficiency: common signs and when to get tested

Vitamin D deficiency and low calcium can be subtle at first. People often notice persistent tiredness, diffuse bone pain, or muscle weakness that limits daily tasks. In children, severe deficiency causes rickets, which shows as delayed growth and soft bones. In adults, chronic low levels can lead to osteomalacia—soft, painful bones—and higher fracture risk when osteoporosis develops. The most reliable way to know your vitamin D status is a 25-hydroxyvitamin D blood test; doctors use that number to guide supplementation. Because symptoms overlap with many other conditions, testing is the best path if you have risk factors, unexplained bone pain, or repeated fractures. Don’t start high-dose supplements without consultation; self-prescribing large doses can overshoot safe limits.