When osteomalacia is in its early stages, you might not have any symptoms, although signs of osteomalacia may be apparent on an X-ray or other diagnostic tests. As osteomalacia progresses, you might develop bone pain and muscle weakness.

The dull, aching pain associated with osteomalacia most commonly affects the lower back, pelvis, hips, legs and ribs. The pain might be worse at night, or when you put pressure on the bones, and are rarely relieved completely by rest.

Decreased muscle tone and leg weakness can cause a waddling gait and make walking slower and more difficult.

Osteomalacia results from a defect in the bone-maturing process. Your body uses the minerals calcium and phosphate to help build strong bones. You might develop osteomalacia if you don't get enough of these minerals in your diet or if your body doesn't absorb them properly. These problems can be caused by:

• Vitamin D deficiency. Sunlight produces vitamin D in your skin. People who live in areas where sunlight hours are short or eat a diet low in vitamin D can develop osteomalacia. Vitamin D deficiency is the most common cause of osteomalacia worldwide.
• Certain surgeries. Normally, the stomach breaks down food to release vitamin D and other minerals that are absorbed in the intestine. This process is disrupted if you have surgery to remove part or all of your stomach, and can result in vitamin D and calcium deficiency. Surgery to remove or bypass your small intestine also can lead to vitamin D and calcium deficiency.
• Celiac disease. In this autoimmune disorder, consuming foods containing gluten, a protein found in wheat, barley and rye, can damage the lining of your small intestine. A damaged intestinal lining doesn't absorb nutrients well, and can lead to vitamin D and calcium deficiency.
• Kidney or liver disorders. These organs are involved in activating vitamin D in your body. Problems with your kidneys or liver can interfere with your body's ability to make active vitamin D.
• Drugs. Some drugs used to treat seizures, including phenytoin (Dilantin, Phenytek) and phenobarbital, can cause severe vitamin D deficiency and osteomalacia.

The risk of developing osteomalacia is highest in people who have both inadequate dietary intake of vitamin D and little exposure to sunlight, such as older adults and those who are housebound or hospitalized.

If you have osteomalacia, you're more likely to break bones, particularly those in your ribs, spine and legs.