Especially during the first two years of life, these points disappear and give way to bones. This process of hardening (calcification) of the cartilage occurs at different rates, with the bones of the hands and wrists being among the first to develop completely. Thus, picking up and moving objects becomes easier for the child.
It is important to note that this is a slow process, in which the definitive formation of all bones in the skeleton occurs only in late adolescence. It is only after this period that the entire cartilage is replaced by bones.
More precisely, when you turn 18, approximately 90% of the peak bone mass has been accumulated. The higher this maximum value, the greater the calcium reserve when aging, thus decreasing the chances of fractures over the years.
What is the origin of rickets?
In order for rickets to reach the levels of clarification we have today, there were some rather curious facts, including the discovery of vitamin D.
It was from the seventeenth century that the first reports of the disease appeared. The fact was noticed due to an outbreak of children with bone deformities and stunted growth. In a short time, the condition was already considered common throughout England and there was a real dispute among scholars as to what its causes would be.
Let’s go back to the context of the time: with the development of industrial cities, pollution became part of the urban scene. This caused children who lived in this environment to stop receiving sunlight. At the same time, those who lived in less developed regions and, therefore, were more malnourished, did not have intense degrees of rickets like those who lived in cities.
Upon realizing this fact, the scientists soon understood that rickets was not related to malnutrition, but to the lack of sun exposure. Some studies later, it was possible to identify a substance that was not yet known: vitamin D.
From the first decades of the twentieth century, supplementation with vitamin D meant that rickets was practically eradicated in industrialized countries. However, the problem is still relatively frequent in less developed regions.
The role of vitamin D
Also known as calciferol, vitamin D is produced by our own body at the time when the skin is exposed to the sun. This fat-soluble hormone is stored especially in the liver and acts directly on the absorption and utilization of calcium and phosphorus, nutrients necessary to keep bones, teeth and muscles healthy.
To give you an idea, when vitamin D is lacking in the body, only 10 to 15% of calcium is absorbed. This can lead to several bone problems, including rickets, in addition to an increased risk of fractures in adolescents and adults.
It is important to note that vitamin D comes in two forms:
- Vitamin D 2 (ergocalciferol): synthesized from plants and yeast precursors, it is also used in high-dose supplements.
- Vitamin D 3 (cholecalciferol): most active form, it is formed when the skin is exposed to sunlight. In addition, it can be found in some foods.
Both vitamin D 2 and D 3 are not active in the body, both of which are metabolized by the liver and kidneys to an active form of vitamin D, called calcitriol . Thereafter, calcium and phosphorus are absorbed by the intestine.
Another important role of vitamin D concerns the increase in immune function and improvement in muscle strength.
Types of rickets
Rickets can be divided into two types: hypocalcemic or hypophosphatemic. Despite having different causes, in both cases there is hypophosphatemia – reduced phosphate in the blood.
Hypocalcemic rickets is characterized by vitamin D deficiency or resistance to its action. It can be subdivided into:
In these situations, the lack of the hormone is usually caused by inadequate sun exposure or insufficient intake of vitamin D, calcium or phosphorus.
Vitamin D-dependent rickets type I
Also called pseudo-deficient rickets in vitamin D , it is an autosomal recessive disorder that manifests itself with vitamin D deficiency syndrome in the first year of life.
Vitamin D-dependent rickets type II
Considered a rare autosomal recessive disease, it is usually caused by mutations in the vitamin D receptor gene, VDR. In such cases, alopecia ( hair loss) is usually one of the first symptoms.
It is usually caused by renal loss of phosphate and is directly related to the genetic factor. It can be subdivided into:
Familial hypophosphatemic rickets
Also called rickets linked to the X chromosome, it is the most common type of hypophosphatemic rickets, in which phosphorus absorption is impaired and levels of calcitriol (active form of vitamin D) are abnormal.
Hereditary hypophosphatemic rickets with hypercalciuria
Autosomal disorder with renal loss of phosphate and high concentrations of calcitriol (active form of vitamin D). In this subtype of the disease, there are defects in the phosphorus reabsorption channels, in addition to the presence of hypercalciuria – excess elimination of calcium in the urine.
Rickets and osteomalacia
Like rickets, osteomalacia is also a type of disease characterized by a defect in bone mineralization, causing fragile and brittle bones. Likewise, it is usually related to a lack of vitamin D. But then what is the difference between the two diseases?
Although conditions are generally associated, while osteomalacia affects adults, rickets is manifested in childhood, more specifically during the growth phase.
When talking about symptoms, osteomalacia does not usually show clear signs. The adult may experience diffuse bone pain in the lower back, pelvis and lower extremities, in addition to muscle weakness. Skeletal deformities, common in rickets, are rare and occur only in long-term conditions.
Some people even tend to confuse osteomalacia with osteoporosis . Therefore, it is important to clarify that in osteoporosis bone mineralization is normal, what actually happens is a decrease in bone mass, in which the bones become weak due to the porosity caused by the loss of calcium.
Today the causes of the disease are quite clear, especially when one understands how the bone development process takes place. In general, the problem will be caused by a lack of vitamin D, calcium or phosphate.
Understand the main causes related to rickets:
Lack of vitamin D
This is the main cause of rickets and may be related to the lack of sun exposure. That’s because UV rays are responsible for stimulating 90% of vitamin D production in our body – just 10 to 15 minutes of direct sunlight can generate 10,000 to 20,000 IU of vitamin D. So people who spend a lot of time indoors, away from the sun, they are more susceptible to suffering from a lack of the nutrient.
In addition, food is also an important factor. With regard to calcium, people who do not consume dairy products – as in the case of lactose intolerants – or those who follow a vegetarian diet, may have nutritional deficiencies.
Problems with absorption of vitamins and minerals
Some underlying conditions can directly affect the absorption of the vitamin in the body. Are they:
- Renal diseases;
- Liver and biliary tract diseases;
- Celiac disease;
- Cystic fibrosis (rare).
The hereditary factor is predominant in hypophosphatemic rickets . In these cases, there is a rare genetic disorder that hinders the kidneys’ ability to control the amount of phosphate excreted in the urine. Thus, the levels of the mineral in the blood remain considerably low, making the bones fragile and flexible.
It is important to note that this type of rickets is not related to vitamin D deficiency.
Especially when talking about a lack of vitamin D, certain factors increase the chances of a person developing rickets:
- Skin color: dark skin produces less vitamin D as it does not react as easily to sunlight as lighter skin – infants and children with darker pigmentation require 5 to 10 times the length of sun exposure to reach the same levels as those with lighter pigmentation;
- Diet: the lack of food intake such as fish, eggs and milk – all sources of vitamin D – favors the disease;
- Age: children aged between 6 and 36 months undergo rapid growth and need more calcium and phosphate to strengthen bones;
- Exclusive breastfeeding: breast milk does not contain enough vitamin D to prevent rickets;
- Geographic location: living in regions where there is less sunlight can decrease the levels of vitamin D in the body;
- Genes: cases of hypophosphatemic rickets in the family favor the onset of this type of disease;
- Use of certain medications: anticonvulsants, glucocorticoids and antiretrovirals can interfere with the body’s ability to use vitamin D;
- Premature birth : being born before the expected time increases the baby’s chances of developing rickets;
- Vitamin D deficiency during pregnancy: babies born after a pregnancy with severe levels of vitamin D deficiency can be born with signs of rickets or develop the disease over the months.
Regardless of the type of rickets, the first signs of the disease can appear in the first year of life and evolve with advancing age, especially in regions that develop more quickly.
The most common symptoms of the disease include:
- Delay in the child’s development and growth;
- Weak bones with greater chances of fracture;
- Teeth problems (stunted growth, abscesses, fragile enamel, crooked teeth, etc.);
- Musculoskeletal pain;
- Difficulty walking;
- Easy tiredness;
- Stunted growth and short stature;
- Excessive sweat on the head;
- Muscle weakness;
- Craniotabes (softening and thinning of the skull bones in newborn babies);
- Recurrent respiratory diseases;
- Tingling in the hands and feet;
- Muscle cramps;
- Seizures – due to the low level of calcium in the blood;
- Alopecia (exclusively in hypophosphatemic rickets).
In the most severe cases, there may be skeletal deformations that include:
- Wide forehead;
- Deformations in the elbows, wrists, ankles and knees;
- Wide bones;
- Changes in the curvature of the spine (scoliosis or kyphosis);
- Arched legs and arms;
- Rachitic rosary (lumps in the rib cage);
- Sternum pushed forward (pigeon breast).
The diagnosis of rickets can be made by a general practitioner, orthopedist, pediatrician or pediatric endocrinologist . Initially, the doctor performs a physical examination to look at specific parts of the body, such as the skull, legs, chest, wrists and ankles, looking for signs of bone deformities.
In order to confirm the diagnosis, tests may also include:
- X-ray of the bones;
- Blood tests to measure levels of calcium, phosphorus, parathyroid hormone, etc .;
- Urine analysis;
- Alkaline phosphatase;
- Arterial blood gases – blood test that checks the acidity in the bloodstream;
- Bone biopsy (very rare).
In the case of nutritional rickets, it is common to detect low levels of calcium and phosphorus in the blood, in addition to reduced values of calcitriol and urinary calcium. On the other hand, alkaline phosphatase, parathyroid hormone and urinary phosphorus levels will be elevated.
Is rickets curable? What is the treatment?
Rickets is a curable disease that does not usually cause major complications. With proper treatment, the child will soon be free of the problem. It is worth remembering that in cases where rickets are caused by underlying diseases, treating this other condition can cure the patient.
Treating measures may differ according to the classification of the disease:
Since vitamin D deficiency is largely responsible for this type of rickets, in most cases the problem is treated with supplementation of this hormone. See the differences:
- Nutritional rickets: in addition to vitamin D replacement, either through food or supplementation, it is common for the doctor to recommend adequate doses of calcium and sun exposure;
- Vitamin D-dependent rickets type I: the patient must replace the lack of calcitriol in the body through supplementation;
- Vitamin D-dependent rickets type II: requires high doses of calcitriol. In this subtype of the disease, treatment is less predictable, as it depends on the degree of defect in the recipient.
Considering that there are some variations of hypophosphatemic rickets, treatment will also depend on the condition. In general, the objective in these cases is to increase the levels of phosphate in the blood to favor the normal process of bone formation.
- Hypophosphatemic rickets linked to the X chromosome: it is treated with the intake of oral phosphorus and calcitriol;
- Hereditary hypophosphatemic rickets with hypercalciuria: requires only phosphorus replacement, without the need for vitamin D supplementation.
Surgical intervention will only be necessary in cases of more severe skeletal deformities, caused by damaged bone growth and / or fractures. Before that, however, it is necessary to correct metabolic and nutritional imbalances, so that there is adequate healing. In such cases, the indicated surgeries include osteotomy and epiphysiodesis.
Drugs that are commonly used to treat rickets are presented in the form of oral or intramuscular supplements and include:
- Vitamin D: ergocalciferol (vitamin D 2 ) and cholecalciferol (vitamin D 3 );
- Calcitriol ;
- Preparations of calcium: calcium carbonate , calcium carbonate + cholecalciferol , calcium phosphate tribasic + associations ;
- Phosphorus preparations: as commercial phosphorus preparations are non-existent in Brazil, the administration of this element is done through phosphate solutions.
Especially in nutritional rickets diagnosed early, adequate supplementation with calcium and vitamin D will promote bone healing in a few months at most. Changes in the curvature of the spine may also resolve in a few years, without the need for surgical intervention.
However, in cases where the problem has not been corrected during the growth period, the bone changes may be permanent.
When there is no adequate treatment, the disease can progress to problems that include:
- Chronic skeletal pain;
- Skeletal fractures without cause;
- Permanent bone deformities;
- More serious breathing problems;
- Cardiac muscle weakness (rare).
Prevention: how can it be avoided?
Some simple measures can help prevent the disease. First, it is important that the child has a healthy and balanced diet, eating foods that contain adequate levels of vitamin D, calcium and phosphorus.
Children who suffer from kidney disorders need to constantly monitor the levels of calcium and phosphorus in the body. The same goes for those with a genetic predisposition to hypophosphatemic rickets.
Exposing your child to the sun properly is also essential, in order for their body to produce sufficient amounts of vitamin D – a few minutes in direct sunlight can be sufficient to avoid the problem.
It is important to say that in this task the sunscreen can be a villain, since the product hinders the production of vitamin D by the body. A protector with SPF 30, for example, can reduce the synthesis of the hormone by 95%.
In order to avoid the possible ills of sun exposure without the use of the filter, it is important that it occurs during times of lower emission of ultraviolet rays (in the morning, until 10 am and in the afternoon, after 4 pm).
In addition to sunlight, vitamin D can be found in some (few) foods, the most relevant of which is cod liver oil. Check out the main sources, as well as the approximate amount of vitamin D per 100g of:
- Cod liver oil: 10,000 IU;
- Fresh salmon: 600-1,000 IU;
- Canned sardines: 300 IU;
- Canned tuna: 236 IU;
- Fresh Shiitake mushroom: 100 IU;
- Boiled egg: 20 IU.
Vitamin D supplementation
It is known that breast milk does not contain sufficient levels of vitamin D. Therefore, as a preventive measure, the Brazilian Society of Pediatrics (SBP) recommends supplementing 400 IU / day (10 mcg) from the first week of life until the 12 months.
After this period, the values rise to 600 IU / day (15 mcg) up to 24 months, including for children on exclusive breastfeeding, regardless of the region of the country.
In the case of premature newborns, oral supplementation should be started when the weight exceeds 1500g and there is full tolerance to enteral nutrition.
And now that you understand the function of vitamin D in the body and its relationship to rickets, it is also important to be aware of the daily calcium recommendation, as this nutrient is closely linked to children’s bone development. Just look: