Introduction
In the middle of the seventeenth century, rickets were identified as a specific condition, which is still widely shared today. Recent reports suggest this disease is becoming more prevalent in industrialized nations in the United Kingdom. A bone condition known as rickets is characterized by high levels of the nutrients calcium (Ca) and phosphate (Pi) in the blood. These abnormalities may result in chondrocyte differentiation and maturation, leading to an unmineralized growth plate. It primarily affects long bones, resulting in poor bone growth, and typical rickets has skeletal deformities like bowlegs and knock-knees.
What Are Infantile Rickets?
The term rickets describes a lack of mineralization of the growth plate cartilage, primarily affecting longer bones. Despite preventive measures, nutritional rickets remains the most prevalent form of the disease globally, attributed to inadequate dietary vitamin D intake or insufficient calcium. Diagnostic tools include a medical history, physical exam, radiologic findings, and biochemical tests.
Rickets is traditionally divided into two categories, despite recent studies suggesting hypophosphatemia as the primary alteration.
-
Calcipenic rickets.
-
Phosphopenic rickets.
What Are the Types of Rickets?
1. Calcipenic Rickets:
- Vitamin D deficiency.
- Vitamin D resistance.
2. Phosphenic Rickets:
- X-linked dominant hypophosphatemic rickets (XHLR) - causes Hypophostaemia to short stature.
- Autosomal dominant hypophosphatemic rickets (ADHR) - causes bone pain, weakness, and pseudo fractures.
- Autosomal recessive hypophosphatemic rickets (ARHR) - causes impaired skeletal mineralization.
- Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) - causes hypophosphatemia and secondary hypercalciuria.
How Does It Occur?
Rickets can traditionally be divided into two main groups: calcipenic and phosphopenic. Lack of calcium intake, which is typically brought on by a vitamin D deficiency, is the main cause of calcium-related rickets. Less frequently, calcipenic rickets is caused by problems with the metabolism of vitamin D or by target tissues that are resistant to calcitriol. The parathyroid-bone axis is activated to maintain blood Ca concentrations in response to decreased intestinal Ca absorption. PTH (parathyroid hormone) causes the activation of the bone resorption process, reduces renal calcium loss, and finally reduces tubular phosphate reabsorption and hypophosphatemia.
Phosphopenic rickets is caused by insufficient or impaired intestinal Pi absorption or abnormal renal Pi excretion, which can occur alone or as a result of generalized tubular dysfunction (for example, Fanconi syndrome).
Reduced apoptosis of the hypertrophic chondrocytes in the growth plate and the resulting emergence of clinical and radiological rachitic changes are both directly caused by hypophosphatemia. Despite the different underlying mechanisms, Hypophosphatemia can be seen as the common factor connecting both calcipenic and phosphopenic rickets.
What Are the Signs and Symptoms of Infantile Rickets?
Bony Deformities: Rickets are characterized by abnormalities of the bones. The maximum frequency reported was between the ages of 4 and 12 months, and they typically manifest before 18 months. Long bone epiphyses and costochondral junctions are primarily affected, where bone growth occurs rapidly. The different types of bone deformities depend on the limb patterns of the child's weight bearing. Forearm deformities are common in crawling infants, whereas, in toddlers, bowlegs (genu varum) or knock knees (genu valgum) are more common.
Extraskeletal Symptoms: Additionally, there may be extra-skeletal manifestations such as proximal muscle weakness, hypotonia, agitation, hypocalcemic seizures, tetany, laryngospasm, and, very rarely, cardiomyopathy. These symptoms, typical of vitamin D deficiency rickets, are less common in people with hypophosphatemic rickets, particularly XLHR. On the other hand, patients with hypophosphatemic rickets may experience spontaneous dental abscesses and enamel defects. Patients with XLHR have reportedly presented with cranial synostosis, or the premature closing of cranial sutures, and Chiari I malformation.
Other Symptoms: Adolescents rarely show florid rickets symptoms. Instead, they typically present with generalized discomfort in the lower limbs and a headache. Due to the expansion of the costochondral junctions, severe rickets may also present with the rachitic rosary. There has also been evidence of frontal projection of the skull, slower growth rate, craniotabes (skull bones become soft), delayed eruption of teeth, broadened fontanelles, and increased susceptibility to fractures.
What Is the Diagnosis of Infantile Rickets?
The doctor will examine the child's bones during the examination by gently pressing them to feel for any anomalies. In particular, the doctor will focus on the child's skull, legs and chest for any abnormalities.
Skull: Infants with rickets frequently have softer skull bones and may experience a delay in the soft spots closure (fontanels).
Legs: Even healthy toddlers have slightly bowed legs, but rickets patients frequently have excessive bowing.
Chest: The rib cages of some rickets patients can become abnormal, flattening and causing the breast bones to protrude. ankles and wrists. Rickets patients frequently have larger or thicker-than-average wrists and ankles.
How Does Nutritional Rickets Affect Children?
Nutritional rickets are brought on by low calcium intake and a vitamin D deficiency. Although the prevalence of vitamin D deficiency has significantly decreased over the past century, it is the most widespread nutritional deficiency.
The age group of infants is particularly susceptible to vitamin D deficiency. Increased scientific evidence suggests that maternal hypovitaminosis D affects maternal and fetal health because fetal vitamin D stores are solely dependent on maternal vitamin D status during pregnancy.
Furthermore, due to the mineral fortification of these products, the risk of vitamin D deficiency is higher in breastfed newborns than in formula-fed neonates (especially preterms).
However, due to mineral deficiency in the third trimester in 80 % of cases, preterm infants, particularly those with birth weights under 1000 g, are at high risk for developing rickets.
It is possible to prevent vitamin D deficiency by getting enough sun exposure, taking vitamin D supplements, boosting the diet, and getting enough calcium. Infants should take 400 IU/day of vitamin D supplements regularly from birth until 12 months. It is recommended that older kids should get 600 IU of vitamin D per day from their diet or supplements.
Conclusion
Although rickets are typically classified as calcipenic or phosphopenic, hypophosphatemia is the common causative denominator of all rickets. Dietary, cultural, environmental, and genetic factors all play a role in the prevalence of nutritional rickets, which is still a significant global issue. By uncovering novel mutations responsible for heritable forms of rickets, researchers gain a deeper comprehension of the fundamental mechanisms underlying these conditions, thereby unlocking fresh therapeutic possibilities.
