What Is Osteomalacia?

Overview

Vitamin D is a fat-soluble vitamin and an essential nutritional component for bone health. This is because it maintains adequate levels of calcium in your body and provides strength to your bones. It is also essential for maintaining many other necessary bodily functions including but not limited to:

• Reducing inflammation
• Regulating cell growth
• Neuromuscular functions
• Immune functions
• Glucose metabolism¹

Therefore, a vitamin D deficiency can cause multiple health issues including osteomalacia - the softening of bones in adults due to prolonged deficiency of vitamin D. Osteomalacia causes defective bone mineralization and improper deposition of calcium in the body which weakens the normally strong, rigid bone structure. 

The overall prevalence of osteomalacia is 10% (every 1 in 10 people) and it occurs more in women compared to men. If left untreated osteomalacia can cause several severe complications such as bone pain, chances of bone fractures, inability to do heavy tasks, etc. 

Thankfully, osteomalacia can be treated by various interventions. It is also important to maintain adequate vitamin D levels - either through diet (fish and cod liver oil), environment (sunlight), or from supplements (available in oral or intravenous forms including Vitamin D3 (Ergocalciferol) and Vitamin D2 (Cholecalciferol).¹

Causes of osteomalacia

In osteomalacia, bone mineralization is impaired and is caused by vitamin D deficiency. Poor absorption and metabolism in a vitamin D deficiency itself has a number of causes including²

• Physical factors such as increased skin melanin and old age 
• Environmental factors such as living in a dark, cold climate 
• Immune conditions such as Crohn’s disease, cystic fibrosis, celiac disease, etc  
• Surgical alterations of the gastrointestinal tract or gastrointestinal diseases such as steatorrhoea - a condition where the body can not absorb the body fats properly and instead excrete them along with vitamin D and calcium in the stool 
• Metabolic kidney and liver diseases, such as tubular acidosis, where the kidneys don't absorb acids from the body as they should do leading to increased acidity and dissolution of the bones 
• Pregnancy (The American Congress of Obstetricians and Gynaecologists recommends 1000 to 2000 IU (International Units) per day for Vitamin D deficient pregnant women) 

You may be ingesting an inadequate amount of dietary vitamin D if you:

• Are lactose intolerant 
• Drink little to no dairy/milk products 
• Follow a vegetarian or vegan diet
• Have trouble properly absorbing vitamin D from the diet due to gastric bypass surgery or a gastrointestinal disease
• Have less phosphate intake (found in meat, fish, dairy, nuts, and vegetables)
• Suffer from a rare cancer that can cause decreased phosphate levels 

Certain medications can also contribute to the development of osteomalacia including:²

• Antiepileptic medicines - such as Carbamazepine, Sodium Valproate, Phenytoin, and Primidone have osteomalacia and bone-related adverse effects  
• Antifungal drugs - such as Ketoconazole are reported to increase the Vitamin D requirements in the body
• Steroids - prolonged use has been implicated in Vitamin D deficiency

Signs and symptoms of osteomalacia

Osteomalacia is a condition of the bones and therefore, its symptoms mainly include affected mobility or impaired skeletal function. Some specific signs include

• Difficulty walking or standing up 
• Tiredness 
• Frequent bone fractures 
• Weak muscles of the arms and legs    
• Bone and hip pain  
• Weakened bones that are more prone to fractures (in the case of falls or accidents) 
• Muscular spasms and pain all over the body
• Hypocalcemia
• Compressed vertebrae
• Pelvic flattening

Management and treatment for osteomalacia

Supplements for calcium, phosphate and vitamin D can be given to patients once they have been diagnosed with osteomalacia. These are prescribed to the patients depending upon the individual case. Adults with tumour-induced osteomalacia are recommended burosumab which is a drug said to improve phosphate metabolism in osteomalacia.³ 

However, the main focus of treatment is to reverse the underlying disorder of vitamin D and electrolyte deficiency. Vitamin D3 (Ergocalciferol) is present mainly in plant sources and Vitamin D2 (cholecalciferol) in meat, fish, and eggs. Due to its longer half-life and potency to increase the Vitamin D levels, cholecalciferol is recommended over ergocalciferol. Besides vitamin D supplements, patients are recommended to take calcium supplements also. Patients with liver or renal disease are recommended to use calcidiol and calcitriol as these patients have poor absorption of vitamin D2 and vitamin D3.

Sun exposure can also help to generate vitamin D and thus it can boost any depleted vitamin D levels. Sun exposure should still be time-limited and done with certain safety precautions such as suncream, protective clothing, and shade to prevent harm from UV radiation

Diagnosis of osteomalacia

Diagnosis of vitamin D is made by various techniques from physical examinations to medical history to imaging studies. All of these methods aim to identify vitamin D deficiency to help in early treatment. 

Medical history and physical examination 

Your GP or a specialist doctor (such as a rheumatologist) should take a thorough medical history from you and perform a comprehensive physical examination of where the pain is occurring. Osteomalacia can be detected at this stage based solely on the physical signs you are displaying. However, to get a proper prognosis of your condition, further tests may be needed. 

Blood tests

Blood tests can provide a timely diagnosis of vitamin D deficiency. 25-hydroxyvitamin D is the active and circulating form of Vitamin D in the body and if a decreased amount is detected in a blood test, this would be grounds for positive diagnosis of vitamin D deficiency. The presence of other markers in blood (such as alkaline phosphatase and parathyroid hormone) can also verify vitamin D deficiency. 

Other procedures 

• Medical imaging  - diagnostic technology such as x-rays can be used to figure out the presence of Vitamin D deficient bones in the body
• Bone biopsy - an advanced method where a part of the bone is removed and observed under the microscope, sometimes with staining to make a final confirmation for diagnosis⁴  

Complications

If left untreated, prolonged osteomalacia can result in many complications and can lead to further deterioration of your overall health. Some possible complications include ⁴

• Fractures - osteomalacia causes softened bones that are more prone to be fractured (for example, from an accident or heavy lifting) and sometimes multiple fractures  
• Bone deformities - softened bones may also give rise to bone deformities such as pigeon chest or bowed legs 
• Secondary hyperparathyroidism - prolonged osteomalacia can trigger secondary hyperparathyroidism (increased activity of the thyroid glands)
• Impaired growth and development 

FAQs

Can osteomalacia be prevented?

Osteomalacia can be prevented with adequate exposure to sunlight and sufficient intake of sources of vitamin D such as dairy products. 

How common is osteomalacia?

Osteomalacia is not a common disorder, affecting around 1 in 1000 people. Conversely, vitamin D deficiency is considerably common, affecting around 1 billion people, usually depending on the climate of the place you live and the diet you eat. 

Who are at risks of osteomalacia?

If you do not intake or absorb an adequate amount of vitamin D in your diet or have been previously diagnosed with vitamin D deficiency, you would be considered prone to developing osteomalacia. Therefore, to mitigate this risk, it is advisable to modify your diet to include more sources of vitamin D or take vitamin D supplements. 

When should I see a doctor?

You should see a doctor when you experience recurring or unbearable pain in your bones or joints. Additionally, you should see your doctor if you feel pain while walking or doing any activity or suffer a fracture, particularly if you get more fractures than usual or that are not explainable from your activities. 

Summary

Vitamin D plays a vital role in mediating various essential bodily functions, namely important for maintaining calcium levels in the body and promoting bone strength. Vitamin D deficiency causes a lot of health issues, therefore, it is important to make sure you are taking enough of this vitamin, either synthesized when the skin is exposed to sunlight and/or obtained from dietary sources such as fish and cod liver oil. Prolonged deficiency of vitamin D, can lead to a condition known as osteomalacia, characterized by softening of the bones. If left untreated, osteomalacia can give rise to several severe complications, including bone pain, increased risk of fractures, and decreased ability to perform physically demanding tasks. You should receive a prompt diagnosis and any appropriate treatment, namely supplementation with vitamin D and associated minerals like calcium and phosphate. However, you should always follow your doctor's advice, do your own research, and follow the instructions on your prescription before you take any new supplements, especially if you have any pre-existing medical conditions. You may also consider getting more (albeit safe) exposure to sunlight and/or consuming vitamin D-rich foods like meat, eggs, and fish.