Rickets

What is Rickets?

Vitamin-D, calcium, and phosphorus play a crucial role in the growth and strengthening of bones. If there’s a problem with these elements leading to improper strengthening, conditions like rickets and osteomalacia may occur. Rickets involves poor strengthening and an abnormal broadening of the ends of the bones. On the other hand, osteomalacia relates to a problem with the strengthening of the hard tissue in the bones.

Usually, both conditions can occur at the same time in children. Whereas only children get rickets, adults can get osteomalacia once the ends of their bones have stopped growing. The first mention of rickets in the world of medicine was made by Whistler, Boate, Glisson, and their friends – all members of the Royal College of Physicians, London, in the seventeenth century.

Rickets caused by poor nutrition is the most frequent bone disease globally.

What Causes Rickets?

Rickets, a condition affecting bone strength in children, is most often caused by a lack of Vitamin D. However, rickets can also develop if a child does not get enough calcium or phosphorus, due to genetic factors, certain medications, or liver diseases. Some medications that interfere with the way Vitamin D works in the body, like diphenylhydantoin and rifampicin, can also lead to rickets.

We can classify rickets into three types based on its causes: calcipenic (caused by lack of calcium), phosphopenic (caused by lack of phosphorus), and a type caused by problems with the bone hardening process, even when calcium and phosphate levels are normal.

Calcipenic rickets often arises from the lack of Vitamin D. Fewer cases are due to inadequate calcium intake or absorption from food, especially in children with malabsorption diseases like celiac disease or cystic fibrosis. Sometimes, a genetic defect that affects the Vitamin D metabolism can also cause calcipenic rickets.

Phosphopenic rickets occurs when there are chronically low levels of phosphate in the blood. This can happen because of a problem with absorbing phosphate in the gut or due to loss of phosphate from the kidneys. Unlike calcium, phosphate deficiency rarely comes from a lack of phosphate in food.

The third type of rickets, called inhibited mineralization rickets, happens when something impairs the hardening of growing bones, despite normal calcium and phosphate levels. This can be triggered by hereditary conditions, certain medications, or exposure to harmful substances like aluminum and fluoride.

Other genetic causes of rickets include vitamin D-dependent rickets, which can be due to deficiency in the active form of Vitamin D or defects in Vitamin D receptor, and congenital hypophosphatemic rickets, which is due to abnormally low levels of phosphate in the blood.

In general, most cases of rickets in young children around the world are due to a lack of Vitamin D, whether from a poor diet or not enough sunlight. A study found that almost 90% of rickets patients had a lack of exposure to sun. Risks of Vitamin D deficiency include breastfeeding without Vitamin D supplements, drinking juice instead of fortified milk, and not eating enough foods fortified with Vitamin D.

Unborn babies can develop rickets if their mothers are Vitamin D deficient. Even where you live can affect your Vitamin D. There are higher chances of Vitamin D deficiency and rickets in latitudes farther from the equator because these areas receive less sunlight. Additionally, even in very sunny areas, people can lack Vitamin D due to cultural or religious clothing customs that cover most of the body, staying indoors most of the time, having darker skin, eating a vegetarian diet, living in polluted areas, and using sunscreens with high protection factors.

Risk Factors and Frequency for Rickets

Rickets is a disease that has seen an increase in cases in both developed and developing countries. The disease is generally more prevalent in developing countries, often found in African, Middle Eastern, and Asian nations where the rate of occurrence can vary from 10% to 70%. In developed countries, rickets have seen a significant fall in prevalence thanks to certain steps. These steps include implementing dietary supplementation of vitamin D, making legislative efforts to improve air quality, and raising public awareness about the role of vitamin D in maintaining healthy bones. For instance, in the U.S., milk fortified with vitamin D (100 IU/cup) was introduced in the 1930s.

• The reported incidence of rickets per 100,000 people varies across countries. In Canada it’s 2.9; in New Zealand it’s 10.5 for children under three and 2.2 for ages 3 to 15; in Australia it’s 4.9; in Turkey it’s 3.8; and in the United Kingdom, it’s 7.5.
• In the U.S., especially in Minnesota, the incidence has seen a significant increase over the past 20 years. Cases in the 1970s, 1980s, 1990s, and 2000s were reported at 0, 2.2, 3.7, and 24.1 respectively.
• This increase in cases can be partially attributed to reduced sunlight (UVB) exposure.
• Children native to Alaska are notably at a greater risk for developing rickets than other U.S. groups. Alaska reports the highest hospitalization rate for rickets among all U.S. regions at 2.23 per 100,000, which is higher than the overall U.S. rate of 1.23 per 100,000
• Rickets is significantly more abundant in Alaska because the state is situated at higher latitudes.

Signs and Symptoms of Rickets

To diagnose rickets, a condition that impacts the bones, a complete medical history and physical examination of the child are required. Information about the child’s sun exposure, diet, growth development, and family’s medical history should be collected. Details such as family history of bone abnormalities, slow growth, hair loss, dental abnormalities, and closely related parents can provide clues to a potential genetic cause.

In physical exams, doctors look for issues in the skeletal system like tenderness, deformities, softness, and unevenness, along with neurological and dental problems. Even if some signs of rickets are not present, the disease could still be developing.

The symptoms of rickets could be different based on the root cause, severity, and how long the child has had the disease. Rickets is often seen in children between 6 months to 2 years of age. This disease can cause various abnormalities mainly in bones which grows rapidly:

• Skull: Softening in infants older than three months, prominences in the forehead area, and large soft spots.
• Chest: Widening of the rib and cartilage junction causing bead-like lumps, pigeon chest, and a groove along the lower ribcage.
• Arms and Legs: Deformities of the limbs, particularly in infants. This includes bowed legs, knocked knees, swollen knees and ankles, and widened wrists in upper limbs.
• Spine: Deformities and forward rounding of the spine.
• Other muscle and bone symptoms: Impaired walking, slow growth, bone softness, bone pain, bone tenderness, narrow pelvic area, low muscle tone, muscle disease proximal to the center of the body, and fractures.

Rickets can also lead to other conditions:

• Dental issues: Late tooth development and thin tooth enamel, which increases the risk for cavities.
• Low calcium levels: Can cause symptoms like tingling, muscle twitching, abnormal sensations, muscle spasms, and seizures. In severe cases, the muscle disease can progress to heart disease and cause death.
• Other brain-related concerns: Excessive buildup of fluid in the brain (also known as rickets hydrocephalus), and increased pressure inside the skull. Closing of the gaps between the bones in the skull (craniosynostosis) can also occur.

Testing for Rickets

If a doctor suspects a case of rickets, a disease that affects how a child’s bones develop, usually due to a lack of vitamin D or calcium, they would use blood tests and images from radiology to confirm the diagnosis.

One important lab test screens for a substance in the blood called serum alkaline phosphatase (ALP). The levels of this substance are often high in those with rickets because this disease affects the way the body forms and repairs bones. Depending on the type of rickets, ALP levels can range from 400-800 IU/L (in phosphopenic rickets where there is a lack of phosphate) to greater than 2000 IU/L (in calcipenic rickets where there is a lack of calcium). This marker is also useful to keep track of the progression of the disease.

Another test measures the level of 25-hydroxyvitamin D in the blood. This test is especially useful when rickets is suspected to be due to a deficiency in vitamin D. Children with this type of rickets usually have a level of less than 10 ng/mL on this test, which is low. A normal range is above 50 ng/mL, insufficient levels are 30-50 ng/mL, and a deficiency is less than 30 ng/mL.

But, it’s important to note that healthy children don’t need to routinely have their vitamin D levels checked. Also, testing for a different form of vitamin D (1,25 dihydroxy vitamin D) can be useful for diagnosing certain genetic types of rickets.

Also, the levels of calcium and phosphate in the blood can be checked. The levels of these minerals may vary depending on the type of rickets a child has. Kidney and liver function can also be tested as these organs play a role in bone health.

In addition to blood tests, getting images of the ends of bones in the arms and legs, and sometimes the ribcage can be helpful. In the early stages of rickets, non-mineralized osteoid can accumulate at the junction between the ends and shafts of bones leading to visible changes. As the disease progresses, bones may appear thin and less dense than normal, and deformities and fractures could occur.

The diagnosis of rickets isn’t just based on one test but rather a combination of signs, lab results, and findings from imaging studies. Even if results from certain tests are normal, the diagnosis of rickets is still possible. However, clinical signs, such as bone pain or skeletal deformities, may not be noticeable in the early stages of the disease.

Treatment Options for Rickets

The treatment for rickets, a condition that affects bone development in children, depends on its cause. Rickets can be due to a lack of vitamin D in one’s diet or it can be genetic (inherited from parents).

If the cause of rickets is a lack of vitamin D, the treatment usually involves a two-part plan: an early intensive phase and then a later ongoing maintenance phase. Both phases would involve some form of vitamin D, along with measures to track the progress of recovery. Adding more calcium to the diet or taking calcium supplements is also recommended to support healing.

There are two main ways to administer vitamin D treatment. First, a single large dose of vitamin D, especially for those who might not be good at consistently taking medication. This vitamin D can be ingested orally or given as an injection. While this method is generally effective and safe, it can sometimes result in high levels of calcium in the blood, i.e., hypercalcemia.

The other method involves smaller daily doses of vitamin D spread over a longer period. Again, the dosage depends on the age of the patient. In infants less than a month old, infants between 1-12 months, or those older than 12 months, would be given 1000 IU, 1000 – 5000 IU, and 5000 IU respectively, over 2-3 months. After that, a daily dose of 400 IU is given as maintenance.

Once treatment starts, improvements in bone pain are usually seen within two weeks. Changes in bone shape take longer – straightening of bow legs or knock knees, for example, could take up to 2 years.

Once the treatment starts, regular monitoring of the patient is carried out to ensure that the treatment is working and that there are no side effects. This usually involves checking the levels of various components in the blood, including calcium, phosphate, ALP, and 25 hydroxyvitamin D. The ratio of urine calcium to creatinine is also examined to check if the treatment needs to be adjusted and to prevent a disease called nephrocalcinosis.

If rickets is caused by vitamin D deficiency, it can be prevented. To prevent rickets, parents, and pregnant women should be educated about the importance of consuming sufficient amounts of calcium and vitamin D and getting enough sunlight. It is recommended that they receive 600 IU per day of vitamin D in combination with other nutrients to prevent rickets in their children.

Another preventive measure is vitamin D supplementation, which is very effective in preventing rickets caused by low vitamin D levels. For instance, infants who are breastfeeding or who drink less than 500 mL of fortified formula per day in their first year should receive 400 IU of vitamin D daily. Beyond infancy, children at high risk of vitamin D deficiency should receive 600 IU of vitamin D daily, either through their diet or by supplementation.

If rickets is due to genetic causes, treatment is usually carried out by a pediatric endocrinologist or a metabolic bone specialist. Depending on the specific type of genetic rickets, the treatment can vary and may include forms of vitamin D like calcitriol or calcium in combination with various therapies.

What else can Rickets be?

When diagnosing Rickets, doctors should consider ruling out other medical conditions that may look very similar based on either lab test results or radiological features. These include:

• Renal insufficiency: A bone disease known as renal osteodystrophy can occur due to reasons such as poor formation of a particular type of Vitamin D, metabolic acidosis, retention of phosphate, aluminum toxicity, and secondary hyperparathyroidism.
• Conditions that increase ALP: Transient hyperphosphatasemia – a harmless condition in which an enzyme known as ALP increases, mostly seen in children under 5 years of age, where both bone and liver fractions are elevated, however, liver enzymes and Vitamin D levels will be normal. Also, diseases that block bile ducts in the liver (cholestatic liver diseases) can lead to elevated levels of an enzyme called gamma-glutamyl transferase.
• Conditions that lead to hypocalcemia (low levels of calcium in the blood): An example of this is primary hypoparathyroidism.
• Other bone diseases: Some of these include osteogenesis imperfecta and congenital syphilis.
• Non-accidental injury.
• Normal variation: Bowlegs may normally be seen in children under 2 years old.
• Skeletal dysplasia conditions such as a disorder called achondroplasia.
• Blount’s disease: This condition leads to pathological bowlegs due to disruption and abnormal growth of the inside aspect of the proximal end of the tibia bone in the leg.

It’s critical for doctors to consider these diagnoses and conduct appropriate tests to provide an accurate diagnosis.

What to expect with Rickets

The outcome for people with rickets, a bone-deforming disease, varies depending on the cause and how serious it is. Rickets caused by nutritional deficiencies often has a positive outcome if caught early and treated promptly. In such cases, the condition can be fully resolved within a few months of starting treatment. However, if no treatment is applied, severe complications can occur.

On the other hand, rickets caused by genetic factors is usually not curable. In these cases, the treatment is aimed at managing symptoms to improve the person’s quality of life and deal with any complications that might arise.

Possible Complications When Diagnosed with Rickets

If left untreated, certain health problems can arise, including stunted growth, bone deformities, numerous pathological fractures, fluid buildup in the brain, increased intracranial hypertension (ICH), and dental issues such as cavities, underdeveloped teeth, and delayed tooth growth. Constantly low calcium levels can result in skeletal and heart muscle diseases, seizures, and in extreme cases, can lead to death.

Possible Complications:

• Stunted growth
• Bone deformities
• Pathological fractures
• Fluid buildup in the brain
• Increased pressure in the brain
• Dental issues like cavities, underdeveloped teeth, and delayed tooth growth
• Constantly low calcium levels
• Skeletal and cardiac muscle diseases
• Seizures
• Potential death

Preventing Rickets

Parents need to understand about the importance of certain foods that are rich in Vitamin D and calcium, as well as foods that have been fortified, or strengthened, with extra nutrients. Spending enough time in the sun, which helps our bodies make Vitamin D, is also vital. Giving Vitamin D supplements to pregnant women and infants is key in avoiding this health issue. This issue can also be significantly helped by government aid programs like the Supplemental Nutrition Assistance Program (SNAP), which provides help addressing deficiencies in nutrition.