In recent years, with the popularity of routine urine tests in children’s physical examinations for admission to schools, more and more children are being seen because they are found to have occult blood in their urine. Seeing the innocent and ridiculous smiles of children and the anxious and worried faces of parents, as a nephrologist, I feel it is necessary for parents to understand and know about hematuria so as not to delay their children’s condition but also to avoid unnecessary fears.
What is hematuria?
Hematuria includes both visual hematuria and microscopic hematuria. The so-called visual hematuria means that there is more than 1ml of blood in 1000ml of urine, and the urine can be in the color of strong tea-like, washed water-like, etc. By microscopic hematuria, it means that the sediment of fresh urine after centrifugation is examined microscopically and exceeds 3 red blood cells per high magnification. In addition, red urine does not necessarily mean hematuria, but we should pay attention to any other causes, such as blood stool or menstrual blood contamination, red urine caused by food or drugs (rifampin, phenytoin sodium), hemoglobinuria caused by hemolysis, myoglobinuria caused by muscle lysis, and red diapers due to uric acid salts in the urine of newborns. Therefore, when you see red urine, you cannot immediately diagnose hematuria, but you have to do a microscopic examination to confirm that there are indeed red blood cells in the urine before you can make a diagnosis.
Microscopic examination of red blood cells is quite important for the diagnosis of hematuria. How should a urine specimen be properly collected?
Firstly, fresh urine, meaning urine that has been solved within an hour, because the cells in the urine will be destroyed if left for too long; secondly, urine that has been left in the middle after cleaning the urethra to prevent contamination of the urine by dirt from the urethra; and again, urine that has been solved by the child under normal conditions, not diluted urine that has been solved after drinking a lot of water, as overly diluted urine can affect the test results.
What are the conditions that can cause hematuria?
Abnormalities of the entire urinary system including the kidneys, ureters, bladder and urethra can cause hematuria. There are also blood system disorders including clotting abnormalities such as hemophilia, thrombocytopenic purpura, and DIC that can also cause hematuria.
The cause of hematuria varies depending on the age of the child.
The more common causes of hematuria in infants and children are urinary tract infections and urinary stones due to anatomical or metabolic abnormalities, etc.
The more common causes of hematuria in preschool children are primary glomerular disease, hereditary glomerular disease, urinary tract infections, etc., and
The more common causes of hematuria in school-age children are primary glomerular disease, secondary glomerular disease, urinary stones, and left renal vein compression syndrome.
In children with urinary tract infections, leukocyturia is predominant and may be accompanied by varying degrees of hematuria, including children with cystitis who may present with significant carnal hematuria. Most abnormalities of the urinary tract anatomy and kidney stones can be detected by ultrasound. Left renal vein compression syndrome tends to occur in children with long, lean bodies and has a good prognosis, but it is important to exclude the presence of other causes of hematuria.
What is known to be closely related to the long-term quality of life and renal function of the child is hematuria due to various glomerular diseases.
What are the glomerular diseases?
Primary glomerular diseases include glomerulonephritis after various pathogenic infections, IgA nephropathy, primary membranoproliferative glomerulonephritis, etc. Secondary glomerular diseases include lupus nephritis, purpura nephritis, hepatitis B virus infection-associated nephritis, hemolytic-uremic syndrome, pulmonary hemorrhage-nephritis syndrome, hepatomegaly, etc. Congenital hereditary Glomerular diseases include thin basement membrane disease, Alport syndrome, etc.
Depending on the specific cause, the clinical manifestations of children with hematuria caused by glomerular diseases vary in severity, and the prognosis also varies.
What factors are associated with the prognosis of children with hematuria?
Blood pressure, urine protein and renal function are the main factors affecting the long-term prognosis of children with hematuria. If abnormalities in these indicators are detected early, early intervention can be made to improve the prognosis. In addition, for children with a family history of hematuria, especially those with relatives who have abnormal renal function and severe proteinuria, the frequency of follow-up is increased compared with those without a family history because the probability of exacerbation is significantly greater in these children than in those without a family history of hematuria, and their follow-up time is increased from once every 6 months to once every 3 months. It is hoped that through close follow-up, changes in the condition can be detected early, and then further tests such as blood tests, renal pathology and genetic tests can be performed to determine the child’s condition and give appropriate treatment to improve the child’s prognosis and prevent or delay the onset of renal insufficiency as much as possible.
Since proteinuria is one of the main factors affecting the prognosis of children with hematuria, what is proteinuria?
Those who meet any of the following.
(1) 3 positive urine tests for protein within 1 week.
(2) 24-hour urine protein quantification >150 mg.
(3) Urine microalbumin/Cr higher than normal 3 times in 1 week.
Anyone with any of the above conditions should seek prompt medical attention.
What are the causes of proteinuria?
The various glomerular diseases mentioned earlier that can cause hematuria, including primary, secondary, and congenital hereditary glomerular diseases, can cause proteinuria to varying degrees, and primary nephrotic syndrome is the most common cause of massive proteinuria in childhood, with clinical manifestations of varying degrees of edema, massive proteinuria, hypoproteinemia, and hyperlipidemia. Children often present with swollen eyelids and lower extremities and decreased urine output after respiratory tract infections or gastrointestinal infections.
Proteinuria often looks frothy, so does frothy urine necessarily mean there is protein?
Not necessarily. The normal human urine is a light yellow transparent liquid, the urine surface tension is low to form fewer bubbles, the urine contains some organic or inorganic substances, it will be enhanced urine tension and appear foam, so the appearance of foam urine does not necessarily mean that there is protein urine, you need to pass a urine examination to clarify.
Should I pay attention to the diet of a child with proteinuria?
A low-salt, high-quality, low-protein diet should be given. Low salt means giving 0.1 grams of salt per kilogram of body weight per day, depending on the child’s weight. By high quality protein, it means animal protein with high biological potency, such as dairy, eggs, fish, lean meat, etc. Give 1.5~2.0g per kg of body weight per day.
Nephritis and kidney disease can cause swelling, so swelling must be a kidney disease?
Not necessarily, such as liver disease to hypoproteinemia, heart disease to sodium retention can cause swelling, in addition to various causes of swollen lymph nodes in the neck to compress the venous return can also cause eyelid swelling, conjunctivitis can also cause eyelid swelling, so when there is swelling, you should check the urine, but still pay attention to the presence of diseases other than kidney.
Finally, I want to tell all parents and friends that both domestic and foreign data have told us that more than 90% of children with submicroscopic hematuria have mild renal lesions and a good prognosis, and the vast majority of them can live a completely healthy life, so for those children with submicroscopic hematuria found by physical examination, parents need not worry too much, otherwise the child will cause unnecessary psychological burden, the main thing is to do a good job The main thing is to do a good job of long-term follow-up work, so that care is not a worry. For children with proteinuria, because urine protein is closely related to the long-term prognosis of the kidneys, it is important to consult the doctor and intervene as early as possible to control the urine protein to a normal level.