Overview

You may think of rickets as a childhood disease from another era. However, this bone-weakening condition remains a threat to certain groups of children.

Nutritional rickets, for example, can develop in kids who don’t get enough vitamin D. In some cases, low levels of calcium or phosphate can lead to rickets.

Hypophosphatemic rickets is a type of rickets related to low phosphate levels in the blood. It’s almost always hereditary. The disease is manageable and doesn’t have to interfere with a long and healthy life.

Symptoms

Hypophosphatemic rickets can be mild or quite severe. Children with a very mild form of the disease may not have any noticeable symptoms. At the other end of the spectrum, the condition can cause serious bone and joint pain. It can also cause the legs to bow outward or inward. In some cases, a child’s legs may appear normal, but walking is awkward or difficult due to abnormal bone development.

These symptoms may be noticeable soon after birth. In many cases, though, you may not see any signs of hypophosphatemic rickets until your child starts walking. Pay close attention to how your child stands and walks. If your baby isn’t standing yet, look at their legs when stretched out straight. If the legs appear bowed or knock-kneed, or your child doesn’t seem as sturdy as they should be, talk to your pediatrician.

Causes

Most cases of hypophosphatemic rickets are genetic. There are several genes that can be mutated to cause the disease. The way the disease presents in a child depends on which gene has the mutation.

One non-hereditary cause of the disease is a benign, or non-cancerous, tumor that affects how the body’s cells absorb phosphate. Phosphate is necessary for healthy bone building and bone repair, as well as for strong teeth and nerve function.

Learn more: How your body uses phosphorus »

Risk factors

Any child born into a family that carries the gene for hypophosphatemic rickets is at a higher risk. The gene is carried on the X chromosome. Females, who have two X chromosomes, tend to have a less severe form of the disease than males. That’s because the non-mutated X chromosome can balance out the one carrying the mutated gene.

What to expect when you see your doctor

If you suspect your baby inherited a gene responsible for hypophosphatemic rickets, ask your child’s pediatrician about genetic testing as soon as possible. A child with the gene may never develop rickets if treatment begins early.

If you don’t know of any potential genetic problems, look for signs of bone problems. The bones and joints in your child’s legs may be painful and tender to the touch. If you think your child’s legs are growing at an odd angle, ask your pediatrician about testing for rickets.

To test for hypophosphatemic rickets, your doctor will check your child’s serum phosphate levels. This is done with a blood test. Because hypophosphatemic rickets is such an uncommon disease, many pediatricians may not know what to look for or how to interpret test results. It’s important to compare your child’s serum phosphate test results to the levels of healthy children of the same age.

There are a few other conditions that can cause similar symptoms to hypophosphatemic rickets. It’s important to find a doctor who has some experience with this particular disease. Children with hypophosphatemic rickets are often treated by a nephrologist or an endocrinologist. A nephrologist is a doctor who specializes in kidney disorders, and an endocrinologist specializes in disorders of the endocrine glands. If you can find a doctor who specializes in bone disorders, your child may be in better hands.

Treatment

Since hypophosphatemic rickets is rare, your child may need to go to a research hospital for treatment. Research hospitals are often affiliated with a university. Treatment almost always includes medications that contain a strong vitamin D and phosphorous supplement.

Your doctor will want to check blood and urine samples regularly. Trying to boost phosphorous levels in the blood can potentially overwhelm the kidneys. This is why a nephrologist is often the specialist overseeing treatment.

In some cases, surgical procedures are necessary to strengthen the bones and improve bone growth. Your child may be in casts or on crutches for months. Once your child’s bones are strong enough and are healing and growing properly, they can resume normal activity.

Complications

Hypophosphatemic rickets can limit your child’s height. This can be avoided if a child is diagnosed and begins treatment early in their growth process.

In some babies with hypophosphatemic rickets, the skull bones can fuse together too soon. This causes the baby’s head to have an unusual shape as the brain grows. In severe cases, neurological damage can occur. Early diagnosis and surgical treatment can correct the shape of the head and allow most children to have normal cognitive development.

Hypophosphatemic rickets can also cause problems with a child’s teeth and other bones.

Outlook

The earlier hypophosphatemic rickets is diagnosed and treated, the better your child’s chances for healthy growth. Even if treatment begins later, it’s possible to get and maintain their serum phosphorus levels at a healthy level.

Surgery to help straighten the legs and improve healthy growth is often successful. Your child may also have to spend a long time in a cast.

A treatment of surgery and medication isn’t always enough. A person born with hypophosphatemic rickets can regress, and the disease can once again start weakening bones. Additional surgeries may be necessary.

The encouraging news is that this disease can be treated successfully and managed well. The most challenging period is usually during a child’s growing years. They’ll need to monitor their bone health into adulthood. For many people, no further treatment is needed once they stop growing.

Takeaway

Having hypophosphatemic rickets can lead to a number of serious bone-related problems, but there are other conditions and lifestyle choices that can also affect bone health. Here are some things you and your child can do to improve the health of your bones:

  • Eat calcium-rich foods, like green leafy vegetables and low-fat dairy products.
  • Take calcium supplements if you’re age 50 or older, and with your doctor’s supervision.
  • Get enough vitamin D from daily sun exposure if possible, or supplements if needed.
  • Do weight-bearing exercises to maintain bone and muscle strength. Weight-bearing exercises include most activities done on your feet, as well as strength training with free weights, machines, or exercise bands.
  • Never smoke.

Hypophosphatemic rickets is a rare disease that affects children. The condition is serious, but there are treatments that have proven to be successful. If you suspect your baby may have any type of bone disorder, talk to their pediatrician. It may require a long process of testing, examinations, and treatments, but starting treatment early will improve your child’s chances for a positive outcome.