Vitamin D is necessary for calcium absorption, and a person who is deficienct in this vitamin is at risk for a condition called osteomalacia, which is a weakening or softening of the bone. Often, osteomalacia is asymptomatic: a patient develops the condition and is not aware of it. However, in other cases, several symptoms may arise. While these symptoms are not always due to vitamin D deficiency, patients who are at risk for developing this vitamin deficiency should be aware that these nerve-related symptoms may indicate that they have developed osteomalacia.
Bone Pain
The pain felt in osteomalacia is termed "bone pain." In a review paper published in "Endocrinology and Metabolism Clinics" in 2010, the authors explain that frequently, patients who experience pain due to osteomalacia differentiate the pain from muscle pain. It is not clear why patients with bone weakening experience pain, but it is theorized that part of the bone, called the periosteum, stretches abnormally when osteomalacia is present, leading to pain signals being sent to the brain. As a result of this pathway, the patient experiences pain at the level of the bone. The authors of the review article further explain that the bone pain of osteomalacia often originates in the lower back and then spreads to the pelvis, hips, ribs, and thighs, in a symmetrical fashion. The pain, perceived as dull rather than sharp, is felt in the bones themselves rather than in the joints.
Hypotonia
Some patients with osteomalacia develop a condition called hypotonia, which is an abnormally low tone to the muscles. The National Institute of Neurological Disorders and Stroke defines muscle tone as the resistance that a muscle has to being moved. So a hypotonic muscle is one that has little resistance to being moved and may be "floppy" or limp. The National Institutes of Health website, MedlinePlus, informs patients that hypotonia is an indication that there is damage to the usual pathway that controls muscle tone, which involves the brain, spinal cord, nerves to the muscle and the muscle itself. Patients with hypotonia due to osteomalacia may find that they feel weaker than usual. Other patients may complain of difficulty walking whether or not they are experiencing bone pain. Weakness or difficulty walking may be suggestions of hypotonia; these are symptoms that should be evaluated by a physician.
Change in Gait
A patient who has osteomalacia due to vitamin D deficiency may notice that his gait begins to be unusual. Gait is a term used to denote an individual's pattern of walking. In patients with osteomalacia due to low vitamin D levels, the abnormal gait is often termed a "waddling gait." This change in walking pattern may be due to muscle weakness, pain in the bones, or some combination of these symptoms. Interestingly, according to the 2010 review article published in "Endocrinology and Metabolism Clinics," gait changes are often more reliable than other symptoms when trying to identify young adults who have osteomalacia.
References
- "UpToDate;" Clinical Manifestations and Etiology of Osteomalacia; C.J. Menkes; March 2010
- "Endocrinology and Metabolism Clinics ;" Osteomalacia as a Result of Vitamin D Deficiency; A. Bhan et. al.; June 2010
- National Institute of Neurological Disorders and Stroke: NINDS Hypotonia Information Page
- MedlinePlus: Hypotonia
- MedlinePlus: Walking Problems
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