In the modern world, almost all parents know about a disease such as rickets. Every pediatrician from the first months of the baby's life warns of the need to prevent this pathology. Rickets refers to acquired diseases that develop as a result of cholecalciferol deficiency, a substance known as vitamin D.
However, in some cases, young children experience symptoms of pathology, despite the observance of preventive measures. In such a case, a disease such as phosphate diabetes should be suspected. Unlike rickets, this ailment belongs to genetic pathologies. Therefore, it is a more serious disease and requires long-term comprehensive treatment.
What is phosphate diabetes?
This is the name of the group of genetic diseases associated with impaired mineral metabolism. In another way, the pathology is called vitamin D-resistant rickets. The dominant type of phosphate diabetes is found in approximately 1 child out of 20 thousand newborn babies. The disease was first described in 1937. Later it turned out that there are other genetic forms of pathology. Phosphate diabetes is most commonly found in early childhood. The attention of parents is attracted by impaired gait and curvature of the bones.
Some forms of pathology are accompanied by other metabolic disorders. Sometimes the disease is asymptomatic, and it can only be detected by laboratory tests. The disease is classified with acquired rickets, hypoparathyroidism and other endocrine pathologies. Treatment should be comprehensive from an early age.
Causes of the disease
The main reason for the development of phosphate diabetes is a violation in the genetic structure. Mutations are inherited. Bearers of the pathological gene can be both women and men. Mutation occurs on the X-linked chromosome, which is dominant. In rare cases, phosphate diabetes can be acquired. It develops against the background of tumors of the mesenchymal tissue, which form even in the prenatal period. In this case, the pathology is called "oncogenic rickets."
The disease belongs to the group of tubulopathies - impaired renal function. Due to the fact that reduced reabsorption of minerals in the proximal tubules, phosphorus deficiency develops in the body. In addition, the intestinal absorption capacity is impaired. As a result, changes in the mineral composition of bone tissue are observed. Often there is a violation of the function of osteoblasts. Men pass the pathologically altered gene only to their daughters, and women - to children of both sexes. As a rule, in boys the disease is more severe than in girls.
Classification of Phosphate Diabetes in Children
There are several forms of the disease that differ in genetic and clinical criteria. Most often, X-linked hypophosphatemic rickets is diagnosed, which has a dominant type of inheritance. However, there are other varieties of pathology. The classification includes the following forms of the disease:
- X-linked dominant type of phosphate diabetes. It is characterized by changes in the PHEX gene, which encodes endopeptidase. This enzyme is responsible for the transport of various minerals through the ion channels of the kidneys and small intestine. Due to a gene mutation, this process slows down, which causes a deficiency of phosphate ions in the body.
- X-linked recessive type. It is characterized by a mutation of the CLCN5 gene, which encodes a protein responsible for the work of chloride ion channels. As a result of the defect, the transport of all substances through the membrane of the renal tubules is disrupted. Bearers of this type of pathology can be both women and men. However, the disease develops only in boys.
- Autosomal dominant type of phosphate diabetes. It is associated with a genetic mutation on chromosome 12. Due to the defect, osteoblasts secrete a pathological protein that promotes enhanced excretion of phosphates from the body. Pathology is characterized by a relatively mild course, in contrast to X-linked forms.
- Autosomal recessive type. It is rare. It is characterized by a defect in the DMP1 gene located on chromosome 4. It encodes a protein responsible for the development of bone tissue and dentin.
- Autosomal recessive type, accompanied by the excretion of calcium in the urine. It occurs due to a defect in a gene located on chromosome 9 and responsible for the operation of sodium-dependent renal channels.
In addition to the listed forms of phosphate diabetes, there are other types of pathology. Some varieties of the disease have not yet been studied.
Differences between Rickets and Phosphate Diabetes
Rickets and phosphate diabetes in children are not exactly the same thing, although the clinical picture of the disease is almost identical. Differences between these pathologies in the etiology and mechanism of development. Ordinary rickets is an acquired ailment associated with a lack of cholecalciferol. This substance is formed in the skin under the influence of sunlight. The diagnostic dose of vitamin D is taken daily for all children from 1 month to 3 years, excluding the summer period. Due to cholecalciferol deficiency, the process of calcium absorption is disrupted. As a result, bone deformity develops.
The difference between phosphate diabetes is that it refers to congenital diseases. With this pathology, the absorption of minerals in the kidneys, in particular phosphates, is impaired. In some cases, calcium deficiency is noted. Due to a violation of the mineral composition of bone tissue, the symptoms of pathologies are similar. The difference between them can be established only after laboratory diagnostics.
Hypophosphatemic rickets in infants: symptoms of the disease
Symptoms of the disease are usually diagnosed in the second year of life. In rare cases, hypophosphatemic rickets in infants are observed. Symptoms that can be diagnosed in infancy are muscle hypotension and shortening of the limbs. The main clinical manifestations are:
- Deformation of the joints of the legs.
- O-shaped curvature of the lower extremities.
- Growth retardation in children - becomes noticeable after 1 year.
- Thickening of the wrist joints and costal cartilage - "rickety bracelets and rosary."
- Pain in the pelvic bones and spine.
- Damage to tooth enamel.
Most often, the main complaint of parents is that the baby has bent legs. When the disease progresses, bone softening occurs - osteomalacia.
Diagnosis of phosphate diabetes and rickets
To identify the pathology, a study of the biochemical composition of the blood is carried out. In this case, hypophosphatemia is noted. The calcium level in most cases is normal, sometimes it is reduced. During the height of rickets, an increase in alkaline phosphatase is noted . Radiography reveals osteoporosis and a violation of bone growth zones. Urine contains a large amount of phosphate. Calciuria is sometimes observed.
Treatment of rickets and phosphate diabetes
Large doses of cholecalciferol are used to treat phosphate diabetes. In some cases, calcium preparations are indicated. Be sure to use medicines containing phosphorus. To improve the condition, vitamin and mineral complexes are prescribed. These include preparations "Vitrum", "Duovit", "Alphabet", etc.
With severe curvature of the bones, physiotherapeutic treatment, exercise therapy and surgical intervention are indicated. Consultation with an orthopedic surgeon is required.
Preventive measures and prognosis
The preventive measures include examinations of a pediatrician and surgeon, walks in the fresh air, the appointment of vitamin D from the first month of life. If there are phosphate-diabetes patients in the family, a genetic study should be performed during fetal development. The prognosis is most often favorable with timely treatment.