Osteomalacia

The most common cause of osteomalacia is a vitamin D deficiency, typically resulting from an inability to form or absorb vitamin D. By helping absorb calcium and phosphorus and maintaining their levels in the blood, vitamin D plays an important role in forming and maintaining bones. When there is a deficiency of vitamin D, calcium and phosphorus are not able to be absorbed or adequately maintained in the blood. This results in an insufficient amount of minerals available for bone formation, ultimately causing softened or weakened bones. 

Vitamin D is produced in the skin by way of sunlight, and if there is a lack of sun exposure, it is unable to form. Vitamin D can also be absorbed through diet. A vitamin D deficiency can result from a diet low in vitamin D, or in cases of malabsorptive conditions; for instance, Crohn’s disease, celiac disease, or if an individual has undergone gastric bypass surgery. Additionally, long term use of certain seizure treatment medications, such as phenytoin or phenobarbital, can interfere with the body’s ability to absorb vitamin D. 

Osteomalacia can also develop in cases of kidney disease or kidney failure. The kidneys play a key role in filtering phosphorus out of the blood. When the kidneys are impaired, it can result in a buildup of phosphorus. The kidneys also activate vitamin D into its active form (known as calcitriol), which ultimately maintains the balance of calcium and phosphorus in the blood. With loss of kidney function, increases in phosphorus levels and decreases in active vitamin D stimulate increased production of the parathyroid hormone, resulting in hyperparathyroidism. Elevated parathyroid hormone levels will work to balance the phosphorus in the blood by stimulating the release of calcium from the bones. As calcium leaves the bones, they can become brittle and weak.

Liver disease can also result in osteomalacia due to changes in the way vitamin D and calcium are metabolized. This can cause impaired bone formation, mineralization, and reabsorption, as well as a decrease in the amount of calcium absorbed from the intestines. 

Additional risk factors for developing osteomalacia include being biologically female and having a darker skin pigmentation. Older adults are also more prone to developing osteomalacia due to decreased vitamin D levels with age.

Symptoms of osteomalacia vary depending on stage. Early stage osteomalacia can often show no apparent symptoms. As it progresses, however, individuals may develop bone pain in the lower back, pelvis, and hips. People often also experience muscle spasms and muscle weakness. For some, osteomalacia can cause muscular and bone pain all over the body.

Over time, the development of fragile bones increases the risk of fractures and trauma. If an individual with osteomalacia experiences any falls, they are more likely to have multiple fractures due to the weakened bone structure.

Osteomalacia treatment primarily focuses on replenishing deficient vitamins and minerals. In most cases, increased dietary intake of vitamin D is required, either through supplements, diet, or both. An increase in calcium or phosphate intake may also be recommended.