Tubulopathies are a heterogeneous group of diseases of the urinary system associated with impaired reabsorption processes localized in the renal tubules. The clinical picture of tubulopathy in children is extremely diverse. Diseases are manifested by symptoms of a deficiency of a certain trace element: weakness, muscle hypotension, dehydration, polyuria, symptoms of rickets, changes in blood pressure in any direction. Urine tests, kidney function, laboratory and radiological diagnostics, and pedigree analysis are carried out by specialists. Treatment of tubulopathy in children is often symptomatic, aimed at normalizing the level of potassium, sodium, calcium and other trace elements. In this article, you can familiarize yourself with the symptoms and features of the treatment of this disease.
Tubulopathy in children
Ignoring the fact that tubulopathies are considered diseases with the development of which there are impaired renal tubule function, some of the nosologies of this group are actually enzymopathies - they are based on disturbances in the structure of the so-called carrier proteins.
In practice, the incidence of tubulopathy in children varies greatly. For example, in medicine, Bartter’s syndrome is extremely rarely diagnosed, but the frequency of renal glucosuria reaches almost 6% among newborn babies (given the family form).
The relevance of this problem is extremely high in pediatrics. Firstly, renal tubulopathy in children often proceeds in the guise of other diseases, which is why they are diagnosed already at the stage of a chronic form of renal failure, and it is practically untreatable. Secondly, the causes of the main number of primary tubulopathies remain not fully understood, which means that only supportive therapy is possible. The clinical recommendations of tubulopathy in children, however, should not be ignored.
Causes of tubulopathy
Almost all tubulopathies occur due to a genetic defect. Mutations can occur in genes that encode the synthesis of proteins that transport various trace elements through the membrane of the cells of the tubules of the kidneys.
There is also a lack of reactions to hormones that regulate the reabsorption of sodium, potassium, bicarbonates, as well as other compounds, and this is due to defects in the development of receptors for these hormones on the cell membrane.
In the protocol of tubulopathy in children, it is said that dysplastic change in the kidneys is considered a possible cause - improper laying of tissue in utero, due to which the very structure of the membranes of tubulocytes changes.
All of the above factors can lead to violations of the reabsorption of various compounds, as well as trace elements from urine. But the same thing can happen in the renal tubule after poisoning with heavy metal salt, drugs, and diseases of accumulation (for example, mucopolysaccharidosis, sphingolipidoses, etc.), when there is also a genetic defect that is located outside the kidneys and urinary system .
Any disease that can lead to impaired functioning of the renal tubule can provoke tubulopathy. This should also include a severe burn, blood diseases, as well as other conditions during which the load on the kidneys increases significantly.
Classification of tubulopathies
The division into primary and secondary tubulopathy in children is based on etiological principles. In the first situation, we are talking about a hereditary and congenital pathology in the renal tubule system, and secondary tubulopathies are directly related to external influences: diseases of another organ and system, blood diseases, burn disease, tumors, etc.
In addition, there is a clinical classification, which is based on the leading ailment syndrome: skeletal deformities, polyuria, nephrolithiasis and other signs. In practice, a classification is often used according to the level of lesion of the tubular apparatus. The following tubulopathies are distinguished:
- with severe damage to the proximal tubule (cystinuria, renal glucosuria, de Tony-Debre-Fanconi disease, etc.).
- with severe damage to the distal tubule (pseudohypoaldosteronism, renal tubular acidosis of the first type).
- with violations of reabsorption at the level of the collecting duct (Liddle syndrome, hyperaldosteronism, Bartter syndrome).
- with total damage to the entire tubular apparatus (nephronophysis).
Symptomatology
So, we have sorted out that most often in practice there are hereditary tubulopathies in children. But what are their symptoms?
Clinical manifestations will depend on the transport of which particular compound is impaired. For example, with hypophosphatemic diabetes, excessive excretion of calcium in the urine will be observed, due to which the symptoms of rickets, highly resistant to treatment with vitamin D, prevail in the clinic.
It should also be noted that rickets-like change also develops with de Tony-Debre-Fanconi disease, but in this case it is combined with multiple bone deformities, as well as pathologies from any other organ (heart and blood vessels, eyes, ENT organs and others).
Pseudohypoaldosteronism is determined by the excessive excretion of sodium chloride from the patient’s body, with urine, feces, and also saliva, so patients have signs of dehydration.
Deficiency in blood glucose with tubulopathy manifests itself in the form of weakness, hunger, polyuria, polydipsia, which is why renal glucosuria is accompanied by signs resembling diabetes mellitus.
Reducing potassium reabsorption with hypokalemia can cause muscle hypotension, as well as the development of paralysis. Violations of the membrane renal transport of amino acids provoke their deficiency, which is manifested by certain signs. For example, with cystinuria, renal colic appears, with Hartnap disease - symptoms of cerebellar ataxia, as well as pellagra. This group of tubulopathies often leads to nephrolithiasis.
As you can see, the symptoms of tubulopathy in children can be completely different.
Diagnostics
If tubulopathy is suspected, pediatricians prescribe a comprehensive examination of urine and the functions of the urinary system. Also, it will be mandatory to determine the level of calcium, sodium, potassium, chlorine in the urine, a glucose test.
Amino acids can be detected in the analysis using chromatography. The calculi will be examined visually using a microscope or detected by x-ray and ultrasound.
Ultrasound diagnostics often confirm abnormalities of the kidneys, ureters, as well as other departments in the urinary system. For most primary tubulopathies, the type of inheritance, the localization of defects in the chromosome, is established, which is why an analysis of the entire pedigree is necessary.
The content of various trace elements is established in the urine, in the blood. With increased excretion, their deficiency is noted. Biochemical blood tests allow you to evaluate glucose. With tubulopathy, the quantitative content of hormones in the blood is also determined. Attention is paid to thyroid hormone and adrenal hormone.
Tubulopathy treatment
Since pathology is most often caused by genetic defects, etiotropic therapy has not yet been developed. The exception is only secondary tubulopathy.
In such cases, the correction of predisposing factors leads to an improvement in the condition. With severe burns, hemodialysis is performed, with lysosomal storage diseases, enzyme replacement therapy methods are indicated that prevent the deposition of various compounds in the renal tubule. Regardless of the main cause of tubulopathy, the doctor prescribes the so-called alkalizing diet, which includes dairy products, potatoes, cabbage and fruits.
Therapy of primary tubulopathies
Therapy of primary tubulopathies is aimed at normalizing the indicator of trace elements that are excreted intensely in the urine. The deficiency is corrected by the introduction of an intravenous solution of sodium chloride, potassium preparations, as well as citrate mixtures.
In the treatment of rickets, a high amount of vitamin D, bisphosphonates, which contribute to the retention of calcium, phosphorus in the patient's body, are used. Severe bone deformity is an indication for surgical intervention. Since tubulopathies often have a delay in physical development, a course of synthetic growth hormone is prescribed.
Prevention
What will be the prevention of tubulopathy in children? It consists in medical genetic counseling by a specialist of future parents. To avoid tubulopathy in children, the doctor's recommendations should be strictly observed.
The result of the disease
Forecasts are not always positive, they depend on the etiology of the occurrence of the ailment. The formation of diabetes insipidus in children leads to rapid death. There is dehydration, which is the cause of death. With de Toni-Debre-Fanconi syndrome, renal failure appears, which requires replacement therapy.
But not everything is so pessimistic. Most tubulopathies are treatable. However, some diseases are asymptomatic. That is why it is important to regularly examine the child.
Conclusion
According to statistics, primary tubulopathy is more difficult, the prognosis for cure is unfavorable, pathologies often lead to death. This is due to the inability to carry out etiotropic therapy, which helps to eliminate the root cause of the development of the disease. With secondary tubulopathies, the prognosis is more favorable.