<unk>  means that you are not getting enough<unk>  D to stay healthy.<unk>  D helps your body absorb calcium. Calcium is one of the main building blocks of bone.<unk>  D also has a role in your nervous, muscle, and immune systems.
You can get<unk>  D in three ways: through your skin, from your diet, and from supplements. Your body forms<unk>  D naturally after exposure to sunlight. But too much sun exposure can lead to skin aging and skin cancer, so many people try to get their<unk>  D from other sources.
Vitamin D deficiency
Hypervitaminosis D
Tumor induced osteomalacia
Disorders of calcium metabolism
Copper deficiency
Secondary hyperparathyroidism
Secondary amyloidosis
Dystrophic calcification