Congenital renal hypoplasia

　　The etiology of the disease is unclear, and it may be caused by the influence of various physical and chemical factors and toxins at a certain stage of renal growth and development. An important pathological feature is the discovery of primitive renal tubules, which are surrounded by renal parenchymal tissue at different differentiation stages. The tubular epithelial cells are cuboidal or columnar, sometimes flagellated, and in an immature state. Primitive or fetal glomeruli and renal tubules may show chondromatous metaplasia. Cysts originate from collecting ducts, and may also originate from glomeruli, with great variation in size and shape, and sometimes may be absent. The size of the kidney depends on the stage of growth and development involved. Some renal hypoplasia lesions are focal.

　　Depends on the extent of involvement. Congenital renal hypoplasia often leads to death in neonates due to bilateral renal involvement. Unilateral involvement may present without symptoms, and may be discovered incidentally in later years. The affected kidney often shows renal ectopia, such as kidneys located in the pelvis. The contralateral healthy kidney is prone to hydronephrosis, kidney stones, and urinary tract infections. Some cases of renal hypoplasia may be asymptomatic, and occasionally, there may be manifestations of a giant ureter or a giant cyst. This disease often accompanies other vascular developmental abnormalities.

　　In addition to its clinical manifestations, renal hypoplasia can also cause other diseases. Renal hypoplasia often easily complicates with hypertension and other symptoms. In some cases, the malformed kidney can be associated with ectopic ureteral orifice, ureteral diverticulum, urethral obstruction, and pelvic syndrome.

　　1Depends on the extent of involvement:Congenital renal hypoplasia often leads to death in neonates due to bilateral renal involvement. Unilateral involvement may present without symptoms, and may be discovered incidentally in later years. The affected kidney often shows renal ectopia, such as kidneys located in the pelvis. The contralateral healthy kidney is prone to hydronephrosis, kidney stones, and urinary tract infections. Some cases of renal hypoplasia may be asymptomatic, and occasionally, there may be manifestations of a giant ureter or a giant cyst. This disease often accompanies other vascular developmental abnormalities.

　　2Common congenital renal hypoplasia in clinical practice includes polycystic, obstructive renal hypoplasia, and renal developmental abnormalities related to genes:The important histopathological feature is the appearance of primitive renal tubules and metaplastic cartilage. Complete unilateral renal hypoplasia can be asymptomatic. In most cases of hypoplasia, renal defects are bilateral, suggesting that gene mutations play an important role in normal renal development. Unilateral diseases may be caused by an acquired injury that destroys the normal expression of genes, thereby affecting the production of proteins that are important for renal maturation.

　　3The renal volume is 50% to 70% smaller than normal:The characteristic is that it contains normal renal cortex and medulla, normal differentiation and development of renal units and ducts, but the number is reduced. Unilateral congenital renal hypoplasia can only be diagnosed when a compensatory hypertrophied kidney is palpated during physical examination, or when an excretory urography is performed due to concurrent hypertension, or when the cause of hypertension is investigated. Chronic renal insufficiency in children is often caused by bilateral renal hypoplasia, and in patients with severe hypertension in the late stage, only kidney transplantation treatment is available. In recent years, with the popularization of prenatal diagnostic methods such as B-ultrasound, there has been an increasing number of prenatal diagnoses of fetal oligohydramnios with unilateral or bilateral renal hypoplasia. After birth, regular monitoring is carried out, and children with unilateral lesions who show an increase in blood pressure early can be considered for unilateral nephrectomy of the hypoplastic kidney if the contralateral side is functionally and anatomically normal and the diagnosis is confirmed.

　　4. The normal mammalian kidney is located in the intermediate mesoderm:The mesoderm differentiates into the pronephric duct before the formation of the mesonephric duct to the ureteric bud. Under the induction of the ureteric bud, the nephrotomes on both sides of the embryo tail differentiate into metanephric buds, and the embryonic development of the kidney is completed by the ureteric bud and metanephric bud. The former gradually develops into the renal pelvis, renal calyx, and collecting duct, and the latter develops into renal tubules and glomeruli. Finally, the renal tubules and collecting ducts are connected to form a normal renal unit. If the two parts of the ureteric bud and metanephric bud cannot develop and connect normally, it will cause renal hypoplasia. Renal hypoplasia can be partial or complete. Most types of renal hypoplasia are accompanied by cysts, suggesting that there is a common mechanism in the formation of various forms of developmental abnormalities.

　　I. Treatment:

　　Children with bilateral renal hypoplasia or unilateral renal hypoplasia with severe contralateral renal disease may experience renal failure, dehydration, and developmental disorders. In cases where unilateral renal hypoplasia is present with the contralateral kidney being normal, no symptoms may be present. Asymptomatic individuals may not require treatment, but dietary guidance, dialysis, or kidney transplantation can be considered if renal insufficiency is present.

　　Segmental renal hypoplasia often manifests as hypertension symptoms, and if unilateral, nephrectomy or partial nephrectomy can be performed. If bilateral lesions and renal insufficiency are present, drug control should be considered. Hemodialysis and kidney transplantation may be used in some cases. Controlling reflux can prevent further renal damage, but it may be ineffective in controlling blood pressure.

　　For renal hypoplasia with ectopic ureteral orifice, urethral obstruction, or pelvic outlet syndrome, small renal resection or corresponding reconstruction surgery can be performed according to specific conditions.

　　Second, prognosis:

　　In the case of good contralateral renal function, the affected kidney can be removed, and the blood pressure can usually return to normal immediately after surgery, and generally within a short period of time. Vision also usually recovers within a short period of time after surgery. According to clinical observations, the younger the age, the faster the postoperative recovery, and the better the prognosis.

　　1. Due to renal artery variation leading to secondary hypertension, renin and angiotensin values can be found to be above normal. For patients with bilateral renal hypoplasia, creatinine and urea nitrogen can be found to be abnormal.

　　2. Ultrasound examination can show one or both kidneys significantly smaller than normal. Radionuclide renal imaging can show one or both renal functions impaired and delayed excretion.

　　3. KUBIVU examination can show significant reduction in one or both renal shadows, poor renal imaging. CT examination can detect significant reduction in renal volume.

　　4. Renal arteriography can show small renal arteries, a narrow renal vascular network range, and sparsity.

　　1. Limit protein intake

　　This is a rather contradictory matter. Protein is the most important nutrient for the growth and development of children, and if it is restricted too early or too strictly, it is harmful to growth. Therefore, the timing should be grasped according to clinical symptoms and blood urea nitrogen levels. The restriction of protein intake mainly involves restricting plant protein (which has a low biological value). High-quality animal protein should be provided in moderate amounts. For moderately decreased renal function, 1 to 2 grams of protein per kilogram of body weight per day (2 to 3 grams per normal child is appropriate). For severely decreased renal function, 0.6 to 1 gram per kilogram of body weight per day should be provided.

　　2. Ensure sufficient energy and carbohydrate intake

　　Congenital renal hypoplasia, bilateral renal involvement often leads to death in neonates. Unilateral involvement may be asymptomatic and may be discovered incidentally in later years. There is no special method for the treatment of renal hypoplasia. Symptomatic treatment includes controlling infection, treating kidney stones, and managing renal failure.