Childhood simple hematuria

　　1. Etiology

　　The source of hematuria can be classified into glomerular and non-glomerular hematuria (urinary tract bleeding).

　　1. Non-glomerular hematuria Urinary tract hemorrhage

　　(1) Urological malformations: Common ones include narrowing of the pelvi-ureteral junction, hydronephrosis, and polycystic kidney, etc.

　　(2) Urological tumors: The most common in pediatrics is Wilms tumor (nephroblastoma), when hematuria occurs, most cases can be palpated in the abdomen.

　　(3) Hypercalcemia: Primary hypercalcemia can account for 1/3 to 1/5 of asymptomatic hematuria. The diagnosis mainly relies on measuring the urinary calcium and creatinine (mg/dl) ratio. Since the incidence of renal calculi in families with idiopathic hypercalcemia is quite high, reaching 30% to 70%, it is necessary to consider the possibility of hypercalcemia when asking about a family history of renal calculi.

　　(4) Walnut phenomenon: The left renal vein runs through the angle between the aorta and the superior mesenteric artery. If the angle is too narrow, it can be compressed, leading to hematuria or proteinuria. The diagnostic criteria proposed by Itami are: ① Unilateral renal hemorrhage. ② Normal urinary calcium. ③ Uniform urinary red blood cells. ④ Minimal changes in renal biopsy. ⑤ Renal vein dilatation seen on ultrasound and CT. ⑥ Pressure difference between the left renal vein and the inferior vena cava of 5 cmH2O. In China, some considered that if the diameter of the distal left renal vein is more than three times larger than the proximal diameter on ultrasound or CT, it can be used as a diagnostic criterion, but later it was found that the detection rate of normal children can reach 10%, and the detection rate of children with glomerular diseases can also reach 30%, and most reports cannot determine whether the hematuria comes from the left ureter. Therefore, relying solely on the ultrasound or CT finding of left renal vein compression is difficult to be used as a diagnosis of the cause of hematuria. Currently, it is considered that the gold standard for the diagnosis of this disease is to measure the pressure difference between the left renal vein and the inferior vena cava, and the left renal venography shows the presence of collateral veins. Since ultrasound can confirm the dilatation of the left renal vein, whether it is indeed the cause of renal hemorrhage is uncertain, and other kidney diseases can also be associated with this phenomenon, the diagnosis should be cautious to avoid delaying the diagnosis of other diseases.

　　(5) Nephrolithiasis: Stationary calculi in the renal pelvis and calyces can only cause hematuria without abdominal pain or lumbar pain.

　　(6) Exercise-induced hematuria: It occurs after intense exercise and disappears within 48 hours of rest.

　　(7) Hyperoxaluria: Both primary and secondary hyperoxaluria are rare. In addition to hematuria, they can also be associated with renal calculi, renal calcification, and renal insufficiency.

　　(8) Other rare causes include renal angioma rupture, pelvovenous-renal pelvis fistula, and spontaneous (or due to renal puncture) arteriovenous fistula hemorrhage. The hematuria originates from one kidney and is quite severe. In addition, mild renal contusion and laceration, as well as renal arterial and venous thrombosis, can also cause hematuria. The diagnosis of the above hematuria is quite difficult, and sometimes renal resection is discovered due to severe hematuria that is difficult to stop.

　　2. Glomerular hematuria

　　In the early stage of acute glomerulonephritis and rapidly progressive glomerulonephritis, gross hematuria can be non-glomerular in nature, especially when using diuretics and in chronic renal failure. In a few cases of nephrolithiasis, glomerular hematuria can also be observed. IgA nephropathy presents with a biphasic pattern. Most cases are chronic diseases caused by glomerulonephritis, including the recovery period of acute glomerulonephritis, the recovery period of purpura nephritis, hereditary nephritis (Alport syndrome), familial hematuria, and solitary hematuria (benign recurrent hematuria). The diagnosis of the first two mainly relies on inquiring about the past history of acute illness and typical purpuric rash.

　　(1) Hereditary肾炎: There is hematuria, small amount of proteinuria, patients may have neural hearing loss, intraocular lesions, and family history.

　　(2) Familial hematuria: Hematuria often occurs after respiratory tract infection, and there is similar hematuria in the family.

　　(3) Isolated hematuria: Persistent microscopic intermittent gross glomerular hematuria. After excluding hereditary glomerulonephritis and familial recurrent hematuria, isolated hematuria, or recurrent hematuria, can be diagnosed clinically. Clinically, it can be divided into two types: ① Recurrent gross hematuria. ② Persistent microscopic hematuria.

　　(4) Portal vascular disease: It is only manifested as hematuria.

　　Mechanism of Disease

　　Pathological changes reported by different experts vary, which may be related to the inconsistency of renal biopsy indications and detection methods. Cubler and Habib reported the histological findings of 245 renal tissues, of which 65% were IgA nephropathy; among the 85 cases examined by electron microscopy, 37 were Alport syndrome, 16 had diffusely thin glomerular basement membranes, and 32 showed normal or mild nonspecific changes. S. Turi of Hungary reported that among 47 cases, 17 had mesangial proliferation, 14 had Alport syndrome, 5 had focal proliferation, 3 had membranous nephritis, 3 had IgA nephropathy, 2 had minimal change and membranous nephropathy, and 1 had focal segmental sclerosis. The results of 50 biopsies at Shanghai Children's Hospital in China showed mesangial proliferative glomerulonephritis in 27 cases (54%), IgA nephropathy in 7 cases (14%), minimal change in 7 cases (14%), focal segmental glomerulonephritis in 6 cases (12%), and IgM nephropathy in 3 cases (6%). This suggests that in China, simple hematuria is more common with mesangial proliferative lesions. Familial hematuria: Glomerular lesions are characterized by thinning of the glomerular basement membrane (〈250nm), and therefore, it is suggested to name this disease as thin basement membrane nephropathy (thinbasementmembranenephropathy). However, in recent years, it has been found that the basement membranes of many non-familial hematuria and some hereditary glomerulonephritis patients are also significantly thinned. Portal vascular disease: In recent years, pediatric reports from abroad have found that some cases show C3 deposition in the walls of the glomerular arterioles entering and exiting the glomerulus in renal biopsy pathological examination of asymptomatic hematuria children, and some may also have IgM and C4 deposition. The lesions are similar to the adult loin pain-hematuria syndrome (loinpainhematuriasyndrome). The glomerular mesangium may show mild proliferation, focal sclerosis, hyalinosis of the arteriolar wall, and fibrous intimal thickening, etc. The pathogenesis is unclear, and it may be related to increased local coagulation activity and platelet activation. In adults, there may be prolonged heparin thrombin time and increased serotonin (serotonin) in the blood. The pathogenesis of exercise-induced hematuria may be related to friction between the posterior wall and the base of the bladder or changes in hemodynamics. Isolated hematuria is a general term for a group of glomerular diseases with different lesion properties but common clinical manifestations. Renal biopsy glomerular lesion types include: normal, mild changes, mesangial proliferative glomerulonephritis (focal, segmental, or diffuse). Immunofluorescence examination may be negative, with slight deposition of immunoglobulins and/or C3, IgA nephropathy, and IgM nephropathy, occasionally showing anti-glomerular basement membrane nephropathy.

　　1. Anemia

　　A condition where the number of red blood cells, hemoglobin content, and hematocrit in a certain volume of circulating blood are all below the normal standard is called anemia. Among them, hemoglobin is the most important. In adult males, it is considered anemia if it is below 120g/L (12.0g/dl), and in adult females, it is considered anemia if it is below 110g/L (11.0/dl). Generally, anemia can be considered. Anemia is one of the most common clinical manifestations, but it is not an independent disease. It may be an important clinical manifestation of a basic or sometimes more complex disease. Once anemia is found, it is necessary to investigate the cause of its occurrence.

　　2. Urinary tract infection

　　It refers to the growth and reproduction of pathogens in the urinary tract, and the invasion of the mucosa or tissue of the urinary tract, causing inflammation. It is the most common type of bacterial infection. Urinary tract infection is divided into upper urinary tract infection and lower urinary tract infection. Upper urinary tract infection refers to pyelonephritis, and lower urinary tract infection includes urethritis and cystitis. Pyelonephritis is further divided into acute pyelonephritis and chronic pyelonephritis, which are more common in women.

　　3. Urinary incontinence

　　It is due to the loss of urinary self-control ability caused by bladder sphincter injury or neurological dysfunction, resulting in involuntary urine leakage.

　　1. Simple hematuria

　　Clinically, there are two forms of manifestation, namely recurrent and persistent, both of which do not have changes such as edema, hypertension, and renal insufficiency.

　　1. Recurrent

　　Between two episodes of recurrent gross hematuria, routine urine tests are normal or show microscopic hematuria. The triggers for hematuria episodes include respiratory tract infections, intense physical activity, etc. The main manifestation is recurrent gross hematuria, with each episode lasting generally not more than 2 to 5 days; the interval between two episodes may vary from several months to several years. During the interval, routine urine tests are normal or show microscopic hematuria. Usually, there is a history of infection or intense exercise 1 to 3 days before the onset of gross hematuria. In a few children, abdominal pain or lumbar pain may accompany the onset of gross hematuria. Renal calyces and renal pelvis static calculi may only present with hematuria without abdominal pain or lumbar pain. Generally, X-ray abdominal films and B-ultrasound can detect them.

　　2. Persistent

　　Persistent microscopic hematuria is often discovered during physical examinations or routine urine tests for other diseases, with urinary protein not exceeding 1g/d. The number of red blood cells in the urine may fluctuate, without other symptoms or signs. Since it is often discovered accidentally, it is difficult to determine the onset date and course of the disease.

　　2. Disease characteristics

　　1. Hereditary nephritis

　　Persistent or recurrent microscopic or gross hematuria, with hematuria being intermittent at onset, accompanied by微量proteinuria, which gradually changes to persistent microscopic hematuria. Hematuria worsens during upper respiratory tract infections, leading to gross hematuria, and urinary protein levels may also increase (usually not exceeding 1g/24h). 30% to 40% of patients have neurosensory hearing loss, and 15% to 20% have intraocular lesions (such as cataracts, astigmatism, and fundus lesions), and chronic kidney disease, deafness, and intraocular diseases may be present in the family.

　　2, Familial hematuria

　　Also known as familial benign hematuria, the clinical manifestations are persistent microscopic hematuria, intermittent gross hematuria, and gross hematuria often occurs after respiratory tract infection. Blood pressure and renal function are normal, and there is no proteinuria. The main basis for diagnosis is the presence of similarly性质的 hematuria in the family, and the presence of hematuria in one of the parents is very helpful for diagnosis. Examination of hematuria in family members should be done multiple times, at least 3 to 4 times, as a single urine test is not enough to exclude the disease.

　　3, Gate血管病

　　In clinical practice, there are no severe lumbar pain symptoms in adults, but only hematuria, including recurrent gross hematuria and recurrent gross hematuria with persistent microscopic hematuria.

　　4, Hypercalciuria

　　Hematuria is the most common symptom of hypercalciuria, usually asymptomatic microscopic hematuria, but can also be transient gross hematuria, and occasionally it can last for several days. Some children may have dysuria or suprapubic pain during gross hematuria. The red blood cells in the hematuria are non-glomerular. In addition to hematuria, this condition can also cause various urinary tract symptoms, such as dysuria, frequency, urgency, daytime urinary incontinence, enuresis, pyuria, and recurrent urinary tract infections.

　　5, Walnut Clamp Phenomenon

　　Also known as left renal vein compression syndrome (left renal vein entrapment syndrome), during puberty, when body length increases rapidly, vertebral bodies are excessively extended, and body shape changes abruptly, the angle formed by the abdominal aorta and superior mesenteric artery (usually 45° to 60°) narrows, and the left renal vein in between is compressed, causing hemodynamic changes. One of the important consequences is left renal hemorrhage (there may also be congestion of the testicular vein or ovarian vein draining into the left renal vein, or varicocele of the spermatic cord), and the proportion of patients with hematuria caused by this syndrome is unknown in patients with hematuria. However, some reports indicate that in 31 patients with non-glomerular hematuria (excluding stones, hypercalciuria, tumors, infection), 15 cases are caused by this syndrome. The characteristics of this type of hematuria are unilateral (left-sided) renal hemorrhage, the red blood cells in the urine are non-glomerular, the degree of hemorrhage varies, and it can be asymptomatic hematuria detected in urine screening, or it can be obvious gross hematuria, and it can recur. Sometimes it is triggered by exercise, and some are accompanied by discomfort or pain in the left lumbar region or abdominal pain. Children may complain of abdominal pain and often prefer to lie on their stomach.

　　Simple hematuria refers to the condition where the number of red blood cells in the urine exceeds the normal level without clear systemic and urinary tract diseases and their symptoms (such as edema, hypertension, renal function impairment, etc.).

　　Currently, there is no effective preventive method, but preventing infection, avoiding overexertion and intense exercise can alleviate and reduce the occurrence of hematuria. Specific dietary recommendations should be consulted with a doctor based on symptoms, and a balanced diet should be maintained to ensure comprehensive and balanced nutrition. The diet should be light, with an emphasis on vegetables and fruits, and smoking and alcohol should be avoided. Do not eat spicy and刺激性 food.

　　1. Hematuria (hematuria)

　　It refers to the excretion of red blood cells in urine exceeding the normal, which is only found under a microscope as an increase in red blood cells, and is called microscopic hematuria; if visible to the naked eye, the urine appears as 'meat water' color or blood-like, even with clots, it is called 'gross hematuria'. The color of gross hematuria is related to the acidity or alkalinity of the urine, neutral or weak alkaline urine is bright red or 'meat water' like, acidic urine is like strong black tea or soot water. The examination methods and diagnostic criteria for microscopic hematuria are currently not unified, and common criteria include:

　　2. Urinary calcium

　　The diagnosis of hypercalciuria mainly relies on the measurement of urinary calcium, when the amount of calcium excreted in the urine exceeds the normal (the normal upper limit is 0.8 per day, >0.6 for 6-12 months), it indicates hyperuricemia and can be diagnosed as hypercalciuria. The confirmation of hypercalciuria requires two or more 24h urinary calcium determinations, if ≥4mg/(kg·d) can be diagnosed, and it should also be referred to medical history, examination (such as blood calcium, phosphorus, blood pH, parathyroid hormone, etc.) to distinguish between secondary and idiopathic, the diagnosis of hyperoxaluria is based on the determination of urinary oxalate, the normal range is 10-50mg/d.

　　3. Urinary protein

　　With微量proteinuria, the increase in urinary protein generally does not exceed 1g/24h.

　　4. Renal biopsy

　　The types of glomerular lesions include normal, mild changes, membranous proliferative glomerulonephritis (focal, segmental, or diffuse), immunofluorescence examination may be negative, with small amounts of immunoglobulin and/or C3 deposition, IgA nephropathy and IgM nephropathy, occasionally presenting as anti-glomerular basement membrane nephropathy, glomerulonephritis in children with portal vein disease can be detected by renal biopsy pathological examination, where C3, IgM, and C4 are deposited in the walls of the efferent arterioles of the glomeruli, the glomerular mesangium may slightly proliferate, have focal sclerosis, and the walls of the small arteries may undergo hyaline change with fibrous intimal thickening, etc. Various imaging examinations are performed to clarify the etiology of hematuria, generally X-ray abdominal films and B-ultrasound can detect static calculi in the renal pelvis and calyces, urinary tract tumors are easily detected by imaging, non-glomerular hematuria such as urinary tract malformations often occurs due to narrowing of the renal pelvis-ureteral junction, leading to hydroureteronephrosis and polycystic kidneys, etc. Imaging examinations, such as B-ultrasound, can often make a diagnosis, walnut phenomenon: B-ultrasound and CT can see the expansion of the left renal vein, in China, it was believed that a B-ultrasound or CT examination showing the distal diameter of the left renal vein to be more than three times larger than the proximal diameter could be used as a diagnostic criterion, but later it was found that the detection rate of normal children could reach 10%, and the detection rate of children with glomerular diseases could also reach 30%, and most reports could not determine whether the hematuria came from the left ureter, therefore, relying solely on B-ultrasound or CT to find compression of the left renal vein is difficult to be used as a diagnosis of the etiology of hematuria. Currently, it is considered that the golden standard for the diagnosis of this disease is to measure the pressure difference between the left renal vein and the inferior vena cava, left renal venography can find the existence of collateral veins, although ultrasound examination can confirm the expansion of the left renal vein, whether it is indeed the cause of renal hemorrhage is uncertain, and other kidney diseases can also be associated with this phenomenon, so the diagnosis should be cautious to avoid delaying the diagnosis of other diseases. In addition, mild renal contusions and lacerations, and renal arterial and venous thrombosis can cause hematuria, diagnosis is quite difficult, angiography can be used to diagnose.

　　1. Avoid eating spicy and刺激性 foods such as scallions, garlic, ginger, chili, and alcohol, and smoke less or not at all.

　　2. Avoid eating fried and greasy foods, and avoid eating roasted and grilled foods. Eat less warm and hot foods, and eat more foods that cool the blood and stop bleeding.

　　3. Avoid eating foods that are likely to cause heat, such as shrimp, crab, beef, mutton, dog meat, and eat less seafood, soy products, animal internal organs, and skin.

　　4. For those with edema, low-salt diet is recommended.

　　1. Treatment

　　It varies with the cause, generally no treatment is required, usually symptoms can be relieved as children grow older or collateral circulation is established, and in some severe cases, vascular reimplantation can be performed. The timely treatment of idiopathic hypercalciuria not only helps to alleviate and eliminate the symptoms caused, but also prevents the occurrence of stones later. Such children should be given sufficient fluid intake and appropriate restriction of sodium salt intake. Avoid eating juices, chocolates, and other foods high in oxalic acid to prevent the formation of calcium oxalate crystals in the urine. For those with gross hematuria, severe frequency, and urgency, appropriate restriction of calcium intake is recommended. Thiazide diuretics, such as hydrochlorothiazide (dihydrochlorothiazide) 1mg/(kg·d), can be given for 4-6 weeks. For those with low blood phosphorus levels, oral inorganic phosphorus (sodium or potassium salt) 1-3g/d can also be used, or ion exchange resin phosphocellulose sodium can be used to prevent intestinal calcium absorption.

　　2. Prognosis

　　Most have a good prognosis. Glomerular hematuria, except for hereditary nephritis, has a good prognosis most of the time. Timely treatment of idiopathic hypercalciuria not only helps to alleviate and eliminate the symptoms caused, but also prevents the occurrence of stones later. The timely treatment of idiopathic hypercalciuria not only helps to alleviate and eliminate the symptoms caused, but also prevents the occurrence of stones later. Such children should be given sufficient fluid intake and appropriate restriction of sodium salt intake. Avoid eating juices, chocolates, and other foods high in oxalic acid to prevent the formation of calcium oxalate crystals in the urine. For those with gross hematuria, severe frequency, and urgency, appropriate restriction of calcium intake is recommended. Thiazide diuretics, such as hydrochlorothiazide (dihydrochlorothiazide) 1mg/(kg·d), can be given for 4-6 weeks. For those with low blood phosphorus levels, oral inorganic phosphorus (sodium or potassium salt) 1-3g/d can also be used, or ion exchange resin phosphocellulose sodium can be used to prevent intestinal calcium absorption.