Osteomalacia and Bone Pain
A Disease Often Caused by Vitamin D Deficiency
Medically reviewed by Oluseun Olufade, MD
Osteomalacia leads to softened bones. It may cause bone pain, muscle weakness, difficulty walking, and an increased risk of bone fracture. It is often caused by vitamin D deficiency, which makes it hard to absorb calcium to support bone. In children, osteomalacia can affect bone growth and may be called rickets. It can lead to heart problems.
A higher risk of osteomalacia occurs in pregnant people, people with darker skin, older adults, and people with limited sun exposure needed for the body to use vitamin D. Certain medications, and conditions like lactose intolerance and allergies, can affect needed calcium.
This article explains osteomalacia symptoms, as well as osteomalacia diagnosis and treatment. It offers information about prevention through nutrient food sources and supplement use that you can discuss with your healthcare provider.
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Osteomalacia Symptoms
You may not notice any symptoms from osteomalacia, especially if your condition is not severe. But some people notice osteomalacia symptoms that include:
Bone pain
Loss of height
Bone fractures
People with osteomalacia also have an increased risk of fractures compared to someone without osteomalacia. So a fall that wouldn’t have caused a fracture in a healthy person might cause a fracture in someone who has osteomalacia.
In people who have very severe osteomalacia, there might be certain deformities of the skeleton. For example, they might have a very hunched back (called kyphosis).
Osteomalacia and Gait Changes
People with osteomalacia may have difficulty with walking, and they may have a kind of “waddling” gait called bilateral compensated Trendelenburg gait. They might have difficulty rising from a chair or walking stairs. Often the pain is worse when you first put weight on your bones.
Osteomalacia Causes
Osteomalacia reflects a disruption in how bone is produced in the body through mineralization. This allows proteins, and minerals like calcium and phosphate, to harden into strong bones. The process continues throughout your life as bone breaks down and is reformed with new bone tissue.
In osteomalacia, minerals don't properly form in the bone. New bone doesn’t harden. There is a decrease in the amount of calcium and other minerals available for making bone.
Vitamin D is important for proper mineralization of new bone matrix. Vitamin D deficiency and other causes include:
Very low vitamin D in the diet (as with some vegetarian diets)
Decreased exposure to sunlight
Cancers that cause low phosphate levels
Digestive system surgery, like gastric bypass surgery
Certain seizure medications (anticonvulsants)
Other conditions that can lead to osteomalacia include celiac disease, Paget's disease, and hyperparathyroidism.
Phosphate Deficiency
Osteomalacia can also be caused by a deficiency in some of the minerals needed to harden bones. So deficiencies of phosphate can lead to osteomalacia. Some of the causes of hypophosphatemia include:
Certain genetic hereditary syndromes affecting phosphate
Cancers that cause low phosphate levels
Certain rare genetic kidney disorders
Rarely, osteomalacia can also be caused by a side effect of certain medications used to treat osteoporosis, such as sodium fluoride and etidronate.
Osteomalacia vs. Osteoporosis
Osteomalacia is different from osteoporosis. Osteomalacia leads to softened bones while osteoporosis leads to bones that are too fragile and brittle. Osteomalacia is due more to mineral loss while osteoporosis is due more to the breakdown of bone and less new bone formation. It is possible to have features of both, but osteoporosis is the more common condition.
Related: Osteomalacia vs. Osteoporosis: What Are the Differences?
How Osteomalacia is Diagnosed
A thorough medical history and medical exam provide the key starting point for diagnosis of osteomalacia. Your clinician must consider your symptoms and your total medical picture. This is important to help rule out other potential causes and eventually get the correct diagnosis.
But healthcare providers often miss a diagnosis of osteomalacia, especially in the disease’s early stages. This is partly because it may cause vague symptoms that can be caused by a number of different medical conditions. For example, the symptoms of osteomalacia may be confused with diseases such as polymyalgia rheumatica, fibromyalgia, or even metastatic bone disease (cancer that has traveled to the bone from elsewhere in the body). Particularly for the latter, your clinician may need to run tests to make sure that an underlying cancer isn’t what is causing your symptoms.
Laboratory tests can provide some helpful clues. Key blood tests may include:
Vitamin D (often very low)
Alkaline phosphatase (usually high)
Parathyroid hormone (PTH)
Calcium
Phosphate
Tests of kidney function
Urinary tests, such as for calcium and phosphate, may be helpful as well.
These key tests may be enough to help diagnose osteomalacia, but sometimes further tests are needed. These might include:
X-rays
Other imaging tests (particularly if cancer needs to be ruled out)
DEXA tests
Rarely, a healthcare provider might want to do a bone biopsy to help definitively diagnose osteomalacia. This is an invasive procedure that requires going under anesthesia. But it isn’t usually needed for a diagnosis.
It is especially important to distinguish osteomalacia from osteoporosis. It can be difficult to tell these apart, as they can have very similar features in terms of symptoms, lab results, and even imaging. For example, the DEXA scan used to diagnose osteoporosis is not good at telling the difference between osteoporosis and osteomalacia. It is also complicated, because a person can have both osteomalacia and osteoporosis. Often, such people are told they have osteoporosis, but the osteomalacia component is not diagnosed.
As part of your process of diagnosis, you might be told that you have hyperparathyroidism or “secondary” hyperparathyroidism. This refers to an elevation in the parathyroid hormone, which helps regulate calcium and other minerals in the body. If you have low vitamin D, this may cause your parathyroid gland to make a lot of parathyroid hormone. If you do have a vitamin D deficiency, and you treat it, this will probably bring both your vitamin D and your parathyroid hormone back into the normal range.
Osteomalacia Treatment
Treatment for osteomalacia will depend on the underlying cause. For someone with osteomalacia due to vitamin D deficiency, vitamin D therapy provides an effective treatment. This works well for the majority of people with osteomalacia. You may need to start out with a very high dose of vitamin D in the first weeks or couple of months after you are diagnosed. You might also need to take calcium supplements.
You clinician may want you to get blood tests to see how well you are responding to vitamin D therapy. If you are responding well, you will probably be able to lower your dose. Depending on the situation, you may need to keep taking vitamin D over the long-term. This is likely to be the case if you have a medical condition or situation that chronically puts you at risk of having low vitamin D. In this case, you are likely to need life-long monitoring.
However, not all types of osteomalacia respond to vitamin D therapy. This might be obvious right away, or it might become apparent after vitamin D treatment doesn’t work for you. For example, if you have osteomalacia because of an underlying kidney problem, treatment of your kidney disease might make the most difference. Or if, for example, your osteomalacia was caused by a side effect of a drug, stopping that drug might be the most effective intervention.
Summary
Osteomalacia leads to soft bones and symptoms like bone pain, muscle pain, and difficulty walking. It can have other causes, such as kidney disease or thyroid changes. It also can have serious consequences, especially with cardiomyopathy (a heart muscle problem) in babies.
Blood and urine tests are used to diagnose osteomalacia, though a DEXA scan or other tests also may be used. Treatment usually relies on improved nutrition, with adequate vitamin D and calcium intake relieving the symptoms. In some cases, it may resolve with a medication changes.
Talk to your healthcare provider if you have concerns or questions about osteomalacia.
Read the original article on Verywell Health.
