Hypoplasia of the kidney

Hypoplasia of the kidney is a congenital anatomical pathology, when the organ is histologically normal, but its size is far from the norm. In addition to abnormal dimensions, the reduced kidney is no different from a healthy organ and even able to function within its miniature size.

[1], [2], [3]

Epidemiology

According to autopsy data, kidney hypoplasia occurs in 0.09-0.16% of cases.

[4], [5], [6], [7], [8], [9], [10]

Causes of the kidney hypoplasia

The cause of kidney hypoplasia is the insufficient mass of the metanephrogenic blastema with normal ingrowth and the inducing effect of the methanephros flow. Therefore, all nephrons have a normal structure and are functionally well-off, but their total number is less than normal by 50%. In essence, this is a miniature norm. The contralateral kidney has more nephrons. Therefore the summary function usually does not suffer.

It is believed that kidney hypoplasia, like any other hypoplasia, is a prerequisite of intrauterine development. Violation of intrauterine organ formation is closely related to external and internal factors affecting the organism of a pregnant woman. Hypoplasia of the kidney, the causes of which often lie in the underdevelopment of metanephrogenic blastema, which is the smallest of the nodes of specific blastema cells, can be a hereditary pathology. If the blood supply of the blastema nodules is disturbed, they are not able to activate the formation of the glomerulus and renal tubules, the organ can not develop and acquire normal dimensions. Hypoplasia of the kidney can be caused by the following reasons:

• Primary underdevelopment (hypogenesis) associated with a genetic predisposition.
• Pyelonephritis, which develops in utero or at the age of up to one year.
• Secondary inflammatory process in hypoplastic kidneys, which are vulnerable in the sense of inflammation of interstitial tissues.
• Intrauterine thrombosis of the renal veins, leading to underdevelopment of the organ.
• Drinking, insufficient volume of amniotic fluid.
• Anomalies of fetal position.
• Infectious disease of the mother - influenza, rubella, toxoplasmosis.

Some authors, specialists in nephropathology, believe that most often hypoplasia of the kidney causes an intrauterine inflammatory nature and is provoked by hidden pathologies in the rudiments of glomeruli and renal pelvis.

Also, hypoplasia can be triggered by external factors affecting the health status of a pregnant woman, they include the following reasons: 

• Ionizing irradiation.
• Injuries, including abdominal bruises.
• External hyperthermia - a long stay of a woman under the rays of the scorching sun, in abnormally hot conditions.
• Alcohol abuse, chronic alcoholism.
• Smoking.

[11], [12], [13], [14]

Pathogenesis

On the pathoanatomical section, the hypoplastic kidney has cortical, cerebral layers and a narrow thin-walled artery typical for renal tissue.

Almost half of children with diagnosed kidney hypoplasia have other anomalies - doubling of the solitary kidney (the only relatively healthy one), eversion (exstrophy) of the bladder, abnormal position of the urethra (hypospadias), narrowing of the renal artery, cryptorchidism.

[15], [16], [17], [18]

Symptoms of the kidney hypoplasia

If the pathology is one-sided, and the solitary (the only relatively healthy) kidney works normally, hypoplasia symptoms may not manifest throughout life. If the solitary kidney does not fully cope with the doubled function, the hypoplastic organ can become inflamed, pyelonephritis develops with a typical clinical picture typical of this disease. Often the cause of persistent arterial hypertension in a child is precisely the kidney hypoplasia. Chronic nephropathic hypertension often leads to the need to remove the hypoplastic kidney, because the renin-dependent form of the disease can not be medically supervised and becomes malignant.

The pathology of the organ's underdevelopment can manifest and is more pronounced in the clinical sense:

• Explicit lag of the child in physical and mental development.
• Pale skin, puffiness of face and limbs.
• Chronic diarrhea.
• Subfebrile temperature.
• Multiple signs similar to the symptoms of rickets - softening of the bone tissue, characteristic protruding frontal and parietal mounds of the skull, flat occiput, curvature of the legs, bloating, baldness.
• Chronic renal failure.
• Arterial hypertension.
• Constant nausea, vomiting is possible.

Bilateral hypoplasia has an unfavorable prognosis for children of the first year of life, because both organs are unable to function and are not subject to transplantation.

Unilateral kidney hypoplasia rarely manifests itself as a specific symptomatology and is randomly diagnosed during clinical examination or a comprehensive examination for a completely different disease.

Hypoplasia of kidneys in newborns

Congenital anomalies in the formation of the urogenital organs have recently been encountered, unfortunately, more and more often. Hypoplasia of the kidneys in newborns makes up almost 30% of all the identified congenital malformations of the fetus. Bilateral kidney hypoplasia in infants is detected in the first days or months of life after birth, since none of the kidneys is able to function normally. Clinical signs of general renal hypoplasia are as follows: 

• Lag in development, possible absence of congenital reflexes (reflex of support, protective reflex, Galant's reflex, others).
• Indomitable vomiting.
• Diarrhea.
• Subfebrile body temperature.
• Explicit signs of rickets.
• Intoxication due to poisoning products of their own metabolism.

The expressed bilateral hypoplasia of kidneys in newborns is characterized by the rapid development of renal failure, which often leads to the death of the baby in the first days after childbirth. If hypoplasia affects from one to three segments of the organ, the child can be viable, but he develops persistent hypertension.

For unilateral hypoplasia, the low concentration ability of a competent organ is characteristic, but when carrying out biochemical analyzes, blood values are within the normal range. Arterial hypertension can develop at a later age, usually in the puberty period.

Hypoplasia of kidneys in newborns is a congenital anomaly due to external or internal effects on the fetus. That is why prospective mothers, pregnant women need not just learn this information, but also do everything possible to maximally neutralize the harmful factors affecting the fetus.

[19], [20], [21]

Hypoplasia of the kidney in a child

Hypoplasia of the kidney in a child aged one year or more may not appear for a long time and is found during examination for an acute form of pyelonephritis or persistent increase in blood pressure. Also, the basis for a comprehensive nephrological examination can be a long pyuria (pus in the urine) or hematuria (blood in the urine). Parents should be alerted to the following manifestations, possibly indicating a pathological condition of the kidneys of the child: 

• Dysuria - retention of urine, polyuria (profuse urination) or frequent urination with small portions of urine.
• Painful urination.
• Enuresis.
• Convulsive syndrome.
• Change in color and structure of urine.
• Complaints of pain in the lower abdomen or pain in the lower back.
• Swelling of the face and extremities (pastoznost).
• Periodic increase in blood pressure.
• Permanent thirst.
• Lag in physical development, weakness.

Hypoplasia of the kidney in a child can be clinically manifested by the following symptoms: 

• Dryness of the skin.
• Pale, earthy skin color.
• Swelling of the face in the preorbital zone (around the eyes).
• A common puffiness is limbs, trunk.
• Persistent hypertension and headache.
• Pathological generalized edema - anasarca (edema of intermuscular tissue and cellulose), characteristic of nephrotic syndrome.
• Piuria, hematuria.
• In boys - cryptorchidism (undescended testicle in the scrotum).

Hypoplasia of the kidney in the child is described in some detail by the Swedish urologist Ask-Upmark as a segmental congenital organ pathology, in which the hypoplastic parenchymal parts of the organ are combined with the underdevelopment of the arterial kidney branches. According to the Swedish doctor, this pathology most often "starts" clinical symptoms in the age of 4 to 12 years in the form of hypertension, visible on the study of changes in the vessels of the eye day, indomitable thirst (polydipsia).

A congenital anomaly is most often determined in the course of medical examinations regarding the registration of a child in a kindergarten or school, less often when examining for existing diseases that are not related to the kidneys.

Forms

In nephrological practice, kidney hypoplasia is divided into three types: 

1. Hypoplasia of the kidney is simple, when an insufficient number of nephrons and calyxes is determined in the anomalous organ.
2. Hypoplasia in combination with oligonephronia (bilateral hypoplasia with a small number of nephrons, glomeruli and enlarged connective tissue, dilated tubules).
3. Hypoplasia of the kidney with dysplasia (malformations of renal tissue - embryonic glomeruli with unformed mesenchymal tissue, often with zones of cartilaginous tissue).

Hypoplasia of the right kidney

Hypoplasia of the right kidney practically does not differ in any way from hypoplasia of the left kidney, at least in the clinical sense or in the functional, the two anomalies are indistinguishable. Hypoplasia of the right kidney can be diagnosed both randomly, and at the intrauterine stage of fetal development or during a primary examination of a newborn baby.

Differentiation of the hypoplastic organ is difficult, since hypoplasia on the echography is extremely similar to another pathology - a wrinkled organ, dysplasia, which is a separate disease. Insufficient quantity of renal glomeruli and calyx is the only difference between the abnormal kidney and the healthy one, the structure and functional capabilities of the underdeveloped organ are preserved. The deficiency of the hypoplastic kidney is compensated by a solitary, that is, a kidney that remains relatively healthy. Hypoplasia of the right kidney indicates some hypertrophy of the left kidney, which increases, trying to perform additional work. The anatomically right kidney should be located slightly lower than the left, because it contacts a fairly large right-sided organ - the liver. It is noticed that hypoplasia of the right kidney is most often found in female persons, which is most likely due to anatomical features of the structure of the female body. Hypoplasia of the right kidney, as a rule, does not require special therapy provided normal compensatory work of the left kidney. If there are no physiological abnormalities other than hypoplasia, there is no infection of the urinary system, there is no nephropathy, there is no urinary reflux (urine throwing), treatment is not required. Of course, if hypoplasia of the right kidney is detected, the left one needs to be protected in order to prevent its disease, which can lead to aggravated complications.

Regular check-ups, observance of a gentle salt-free diet, some restriction of physical exertion, avoidance of hypothermia, viruses and infections are quite sufficient measures for a full-fledged qualitative life with one functioning kidney. If a severe condition develops accompanied by nephroptosis of the sole organ, hypertension or pyelonephritis in acute form, nephrectomy is possible.

[22], [23]

Hypoplasia of the left kidney

Anatomically, the left kidney should be located just above the right one, so the hypoplasia of the left kidney may appear more symptomatic in the clinical sense.

As signs indicating the underdevelopment of the left kidney, there may be aching pain in the lower back. In addition to periodic pain of other signs, hypoplasia of the left kidney, as a rule, does not show. Sometimes a person can live a lifetime with a hypoplastic left kidney, even without knowing it, especially if the right kidney fully provides homeostasis, although hypertrophied due to vicar (substitution) function. It should be noted that the absence of pathological symptoms with underdevelopment of the body is not a guarantee of safety in the future: any infection, hypothermia, trauma can provoke pyelonephritis, the formation of persistent arterial hypertension and a significant decrease in the collateral working kidney activity. It is believed that the hypoplasia of the left kidney is most often defined as a congenital pathology in males, although there is no precise statistical information confirmed by the international medical community.

It should be noted that hypoplasia of the left kidney, as well as underdevelopment of the right kidney, have not been fully studied, so there are still disagreements in the field of therapy standards for this anatomical pathology. Hypoplasia of the left kidney, under the condition of normal right operation, does not require treatment. The patient needs only regular examinations, it is necessary to periodically give blood and urine for laboratory tests and undergo an ultrasound examination.

Diagnostics of the kidney hypoplasia

At present, it is sufficient to carry out MRI or MSCT, if necessary - in combination with dynamic nephroscintigraphy. Clinically, with this defect, the condition of the contralateral kidney is of great importance, since its disease or trauma can lead to kidney failure.

A dysplastic kidney or true kidney hypoplasia is characterized by a decrease in this organ with a general underdevelopment of its structure, vessels and this type of anomaly can be bilateral. The cause of dysplasia of the kidney is insufficient induction of the methanephros flow pathway to differentiation of the metanephrogenic blastema after their fusion. Clinically, most often this defect of kidney development is manifested by arterial hypertension and symptoms of chronic pyelonephritis, which is associated with an abnormal structure of both the intraorganic vasculature, the main vessels, and the bowl-and-pelvis system. A two-pronged process is characterized by renal failure. Differential diagnosis of dysplastic kidney is carried out with a dwarf and shriveled kidney.

[24], [25], [26], [27], [28], [29]

Differential diagnosis

Differential diagnosis of kidney hypoplasia is performed with kidney dysplasia and wrinkled kidney. Proof of hypoplasia is the normal structure of the renal vessels, the calyx and pelvic system, the ureter, which could previously be established with excretory urography, retrograde ureteropyelography, renal angiography, and dynamic nephroscintigraphy.

Treatment of the kidney hypoplasia

If the cause of arterial hypertension is in the kidney dysplasia or against the background of this anomaly, pyelonephritis is diagnosed, then the following kidney hypoplasia treatment is indicated: nephrectomy.

Underdevelopment of one or two kidneys is a complex pathology, due to late detection and diagnosis. Hypoplasia of the kidney treatment involves a variable, depending on the type of hypoplasia and on the state of the solitary, functioning kidney.

The tactics of treatment of unilateral hypoplasia are developed taking into account the individual characteristics of the patient's state of health. Most often, therapeutic measures are similar to treatment of patients with one kidney.

If the collateral kidney performs a doubled function in its entirety, no special treatment is required. Therapeutic actions are possible only if there is a suspected pyelonephritis of the hypoplastic kidney. Some experts recommend performing a nephrectomy of an underdeveloped organ, even if the collateral kidney is healthy. This is explained by the fact that an underdeveloped organ is a potentially dangerous hotbed in the infectious and immune sense and can affect a healthy kidney.

Also kidney hypoplasia treatment also suggests in the case of persistent hypertension, not amenable to standard drug therapy. The removal of the hypoplastic kidney is generally indicated in adults. Children who have a hypoplastic kidney capable of working for at least 30% of the prescribed volume, are shown dispensary records, observation, regular examinations and symptomatic treatment with suspicion of the slightest functional abnormalities.

If severe bilateral hypoplasia of the kidney is detected, the treatment should be surgical, usually both abnormal kidneys are removed. The patient is transferred to hemodialysis and he is undergoing a donor kidney transplant.

Forecast

If the anomaly is determined at an early age and is diagnosed as bilateral hypoplasia, attempts may be made to restore and correct the water-electrolyte balance, neutralize azotemia (intoxication of blood with nitrogenous products). However, with pronounced bilateral hypoplasia, the child most often dies from uremia and heart failure (decompensation). The prognosis is usually unfavorable, children with such severe pathology live from 8 to 15 years.

[30], [31]