Osteomalacia

What is Osteomalacia?

Vitamin D deficiency, which is the most common nutritional shortage among both children and adults, can lead to certain medical conditions. In adults, a prolonged lack of vitamin D can cause a condition called osteomalacia, a bone softening disorder resulting from improper mineralization of a part of the bone called osteoid. However, in children, the same deficiency leads to rickets, a disease caused by inadequate mineralization at growth plates in their cartilage.

Bone is made up of several types of cells that work together to remodel or rebuild bone. One type of cell, the osteoclast, breaks down bone by releasing an enzyme called collagenase. Then, osteoblasts create an osteoid matrix, a framework of collagen where inorganic salts gather to form hardened bone. This complex process is managed both directly and indirectly by certain hormones, specifically parathyroid hormone (PTH) and calcitonin. These hormones respond to the level of calcium in your blood.

In cases where there’s a decrease in vitamin D or its by-products, our bodies maintain normal calcium levels by getting calcium from our bones. This is achieved by releasing PTH from the parathyroid glands when calcium levels in the blood are low due to a lack of vitamin D. This hormone aims to restore normal calcium levels by drawing calcium from the bones. Consequently, if calcium is consistently taken from the bones, osteomalacia can occur. Thus, adults who have conditions that interrupt the normal processing and production of vitamin D can be at risk for developing osteomalacia and experiencing its symptoms.

What Causes Osteomalacia?

Osteomalacia is a condition where the bones become soft due to problems with bone formation. It involves the process where a compound called hydroxyapatite is placed on the “blueprint” of the bone, also known as the osteoid matrix. We can commonly overlook a variety of causes for this disease, as detailed below.

Lower Vitamin D Production:

Certain situations can lead to a decrease in vitamin D production, which is crucial to our body’s absorption of calcium:

– Cooler climates can limit skin exposure to sunlight, hampering the skin to generate vitamin D.
– Having darker skin or more melanin can interfere with the absorption of sunlight.
– Obesity can result in fat seizing vitamin D, reducing the amount available for use.
– As individuals age, the production and storage of vitamin D tends to decrease.

Lower Vitamin D Absorption:

There are conditions in which the body might not be able to absorb enough vitamin D:

– Dietary insufficiency can cause a deficiency even if there’s enough sunlight exposure.
– Diseases such as Crohn’s disease, cystic fibrosis, celiac disease, cholestasis, and modified digestive systems can interfere with absorbing vitamins.

Altered Vitamin D Metabolism:

Other medical conditions can obstruct the body’s ability to utilize vitamin D:

– Chronic kidney disease can cause the decline of an enzyme needed for vitamin D production.
– Nephrotic syndrome, a kidney disorder, leads to abnormal loss of a protein that carries vitamin D in the blood.
– Liver conditions like cirrhosis and others result in deficient vitamin D production.
– Pregnancy can decrease vitamin D levels, thus doctors recommend pregnant women to take daily supplements.

Low Levels of Phosphate or Calcium:

Some conditions and actions can result in low levels of phosphate or calcium, which can contribute to osteomalacia:

– Renal tubular acidosis, a condition affecting kidney function, can alter the absorption of certain ions.
– Frequent IV iron injections can decrease phosphate levels.
– A rare disease linked to benign tumors can lower phosphate levels, known as tumor-induced osteomalacia.

Medications:

Some medications can cause a vitamin D deficiency:

– Certain antiepileptic drugs, like phenobarbital, phenytoin, and carbamazepine, increase the breakdown of vitamin D.
– Other medications like isoniazid, rifampicin, and theophylline can also cause a vitamin D deficiency.
– Antifungal medicines, like ketoconazole, raise vitamin D needs by inhibiting a necessary enzyme.
– Long-term steroid use may also lead to vitamin D deficiency.

Risk Factors and Frequency for Osteomalacia

It’s reported that as many as 25% of adult Europeans have osteomalacia, a bone disease, which is commonly identified during autopsies. However, the true number of people with osteomalacia around the world is likely underestimated. Some people are more at risk of getting this disease, including those with dark skin, people who don’t get much sunlight, those with lower income, individuals with a poor diet, and people who often wear clothing covering their whole body.

Different areas worldwide have varying risks, and these are often linked to location, culture, and ethnicity. Doctors and other health workers should consider these factors along with any related health issues when they’re deciding whether to do further tests or recommend taking vitamin D.

• As many as 25% of adult Europeans might have osteomalacia based on autopsy studies.
• The real number of people with osteomalacia worldwide is probably underestimated.
• Risk factors include having dark skin, limited sun exposure, lower socioeconomic status, poor diet, and wearing full-body clothing.
• The risk of getting osteomalacia varies by location, culture, and ethnicity.
• Healthcare professionals should think about these factors as well as any related health signs when deciding on further testing or recommending vitamin D.

Signs and Symptoms of Osteomalacia

When doctors are checking for osteomalacia, a condition that softens the bones, they need to look at your family’s medical history and any past surgeries you’ve had. They may also ask about your general lifestyle activities, hobbies, food choices (for example, whether you’re a vegetarian), and get a sense of your socioeconomic status.

Osteomalacia can have various symptoms, but they’re not always clear-cut. They can include:

• Weakness and wasting away of the muscles near your body’s surface
• Muscle aches and joint pains
• Muscle spasms
• A change in how you walk, like a “waddle”
• Changes to your spine, limbs, or pelvis, specifically any deformities (usually seen with long-term osteomalacia)
• Pain in the bones of your lower back, pelvis, or lower legs, which gets worse with physical activities and bearing weight
• An increased likelihood of falling down
• Conditions related to low calcium levels in your blood, like seizures or muscle cramps

Testing for Osteomalacia

Osteomalacia, a bone disease that leads to softening of your bones, can be tricky to diagnose since there isn’t one specific lab finding that can confirm it. However, several indicators can suggest the presence of osteomalacia. These include low levels of phosphate or calcium in the blood (hypophosphatemia or hypocalcemia) and increased activity of an enzyme called alkaline phosphatase, usually associated with bone diseases.

Some experts argue that having either hypophosphatemia or hypocalcemia together with a high level of bone alkaline phosphatase is enough to suspect osteomalacia. Other signs that can appear as the disease progresses include low bone mineral density and an increase in specific areas in the bone that show up in a bone scan, known as Looser zones.

Four characteristics can indicate definite osteomalacia: hypophosphatemia or hypocalcemia, high bone alkaline phosphatase activity, muscle weakness or bone pain, and bone density that is less than 80% of the average for young adults. If you have all four, the diagnosis is definite osteomalacia. If you have the first two and two out of the last three, it suggests possible osteomalacia.

Another set of criteria proposed for diagnosing osteomalacia includes high levels of parathyroid hormone (PTH), high alkaline phosphatase levels, low calcium levels in urine, and low calcium intake or low levels of a type of vitamin D (calcidiol). These criteria are useful to diagnose osteomalacia when there are no other kidney or liver issues. Also, if the level of vitamin D, specifically 25(OH)D, in your blood is very low, it is a good indicator of the disease.

X-rays can sometimes show Looser zones, or pseudofractures, which are classic signs of osteomalacia. They appear as clear horizontal lines in areas of the bone. These can typically be seen on both sides of the body and symmetrically at the hip joints, neck, or leg shafts. X-rays can also show less distinct bone tissue in the vertebral body due to poor mineralization of osteoid, which is the organic part of the bone. This isn’t always required for diagnosis, but when present, it shows reduced bone density in the spine, hip, and forearm.

If these noninvasive methods do not provide a clear diagnosis, or the cause of osteomalacia is not easy to determine, doctors may conduct a bone biopsy. In this test, a small piece of bone tissue is removed from your hip bone, and this sample provides the most accurate diagnosis of osteomalacia.

Treatment Options for Osteomalacia

If you have been diagnosed with osteomalacia, also known simply as softening of the bones, your doctor will first try to figure out what is causing it. The treatment will mainly aim to address this underlying problem and restore your body’s levels of Vitamin D and any other nutrients or minerals that may be lacking.

This treatment is important when Vitamin D deficiency is identified as the cause of your symptoms. It can greatly improve your muscle strength and relieve pain in your bones within a matter of weeks. Your doctor will keep a check on the levels of calcium in your blood and urine, initially after 1 and 3 months, and then every 6 to 12 months. The level of Vitamin D in your blood can be checked 3 to 4 months after you start the treatment. If the calcium levels in your blood or urine are found to be too high, your doctor can adjust the treatment to prevent an overdose of Vitamin D.

For those with a severe Vitamin D deficiency, doctors may recommend specific types of Vitamin D. These include ergocalciferol, also known as Vitamin D2, which comes from plants and fortified foods, and cholecalciferol, which is Vitamin D3, typically found in fish, meat, and eggs. Comparatively, Vitamin D3 seems to work better for increasing Vitamin D levels in the body.

Besides Vitamin D, you should also take at least 1000 mg of calcium each day if you’re being treated for a Vitamin D deficiency. This is because not having enough calcium can also contribute to the development of osteomalacia. However, if your body isn’t properly absorbing nutrients (a condition known as malabsorption syndrome), you may need to take more calcium. If you have liver or kidney disease, you may be unable to effectively process Vitamin D2 or D3, and in such cases, other forms of Vitamin D such as calcidiol or calcitriol may be considered.

The achievement of treatment for osteomalacia is marked by an increase in calcium excretion in urine and a rise in bone mineral density. Calcium and phosphate levels in your blood may return to normal a few weeks into treatment. However, the levels of bone alkaline phosphatase, a substance that’s often higher in people with bone disorders, may take a few months to normalize.

What else can Osteomalacia be?

When a patient shows certain symptoms, doctors start by making a wide-ranging list of possible conditions, also known as a differential diagnosis. They use medical history, physical check-up, lab tests, and imaging to narrow down this list. Nonetheless, some conditions have identical symptoms and lab results, thus traditional diagnosis methods cannot rule them out. Conditions like metastatic diseases, primary hyperparathyroidism, and renal osteodystrophy, which affect the bone, often present such diagnostic challenges.

Both osteoblastic bone metastases and multiple myeloma bear similar lab results. They both also cause multiple sections of bone to glow brightly during bone scans (zones of uptake). Understandably, further investigation is needed to exclude the possibility of any underlying cancers. Multiple myeloma showcases similar symptoms like bone pain and muscle weakness, but it also shows holes in the bone (lytic lesions) under X-ray and is often accompanied by anemia and decreased kidney function.

Primary hyperparathyroidism typically shows low phosphate levels in the blood (hypophosphatemia), increased bone enzymes (bone alkaline phosphatase), and increased zones of uptake, quite like osteomalacia. However, it unusually leads to high calcium levels (hypercalcemia) in the blood, contrary to what is usually seen in osteomalacia. In renal osteodystrophy, patients usually have high levels of phosphate in the blood (hyperphosphatemia), another inconsistency with osteomalacia where hypophosphatemia is observed.

What to expect with Osteomalacia

Osteomalacia is a condition that affects the bones and can generally be prevented. It’s often caused by not getting enough vitamin D, so in most cases, getting more of this vitamin can help treat and even cure it. If there are other health issues contributing to the development of osteomalacia, the treatment will need to be customized and adjusted accordingly.

Once the problem is discovered and a suitable treatment plan is made, lab test results might start showing improvement within weeks. Patients will start to feel better around the same time. After treatment has begun, regular lab tests will be needed to check how the treatment is working. In terms of total healing time, completely reversing osteomalacia might take several months to over a year, depending on what’s causing the condition.

Possible Complications When Diagnosed with Osteomalacia

If osteomalacia, a condition characterized by soft bones, isn’t managed properly, a variety of problems can arise due to inadequate bone mineralization. One such issue is insufficiency fractures, also called Looser zones, which can cause bone pain and can happen with little to no injury. These fractures typically occur on both sides of the body, are perpendicular to the outer layer of the bone, and often affect areas like the femoral neck (near the hip), the pubic and ischial rami (parts of the pelvis). There are even instances of Looser zones occurring in other parts of the body like the ribs, shoulder blades, and collarbones.

Common Complications of Untreated Osteomalacia:

• Insufficiency fractures or Looser zones causing bone pain
• Fractures occurring in the femoral neck, pubic and ischial rami
• Rare instances of fractures in the ribs, shoulder blades, and collarbones

Spinal compression fractures, although less frequent, are generally associated with osteoporosis, a condition that weakens bones. There have also been findings of kyphoscoliosis, a type of deformity that leads to abnormal curvature of the spine, in people with long-term osteomalacia.

Preventing Osteomalacia

Some people are more likely to develop osteomalacia, a condition characterized by softening of the bones due to a lack of vitamin D. The following groups have a higher risk:

• People of darker skin tones
• Individuals who don’t get a lot of sunlight on their skin
• People who consume diets that lack adequate levels of vitamin D
• Individuals on medications that might cause vitamin D deficiency
• Overweight or obese individuals
• Older individuals
• People with conditions that prevent the gut from properly absorbing nutrients, known as malabsorptive syndromes
• People with kidney or liver disease

While there isn’t enough evidence to suggest that people without symptoms should have their vitamin D levels checked, it’s essential for doctors to be aware of these risk factors. This allows them to educate their patients about these risks and where possible, suggest feasible lifestyle changes to mitigate these risks. Doctors might sometimes overlook the lack of vitamin D-rich foods and insufficient sunlight exposure, particularly in patients from conservative cultures.

The major natural sources of vitamin D are mostly found in meat and fish, which don’t form part of vegetarian diets. For vegetarians, there are other sources of vitamin D, such as fortified milk, yogurt, cheese, orange juice, bread, and UVB-enhanced mushrooms. However, further research needs to be done to understand the benefits of consuming these foods.