Pediatric renal diabetes
Introduction
Introduction to renal glycosuria in children Renal glucosuria refers to the presence of diabetes in the presence of normal or lower than normal renal glucose threshold. The patient's fasting blood glucose and glucose tolerance are normal, and various congenital or acquired causes (such as familial renal diabetes) Various renal tubular acidosis, etc.) cause renal proximal tubule damage, resulting in renal tubular reabsorption of glucose, and glomerular filtration rate is still normal, due to a decrease in renal sugar threshold, glycosuria, often accompanied by amino acids, Reabsorption disorders such as bicarbonate and uric acid. However, some patients with renal diabetes can be converted into true diabetes, which is divided into primary renal glucosuria and secondary renal glucosuria. basic knowledge The proportion of illness: 0.0035% Susceptible people: children Mode of infection: non-infectious Complications: malnutrition, dehydration
Cause
Pediatric renal diabetes
(1) Causes of the disease
Primary renal diabetic
Also known as familial renal glucocosuria (familialrenal glocosuria), mostly autosomal recessive genetic disease, and some are dominant inheritance, clinically rare.
(1) Type A: It is a true renal tubular dysfunction, which is rare. It is characterized by a decrease in the renal sugar threshold and the maximum absorption rate of renal tubular glucose. Even if the blood sugar is not high, the renal tubular absorption of glucose is lower than normal.
(2) Type B: It is because the reabsorption function of glucose in individual nephrons is reduced, and the blood glucose does not reach the maximum absorption rate of renal tubular glucose.
2. Secondary renal glycosuria
Less common, can be secondary to chronic interstitial nephritis, nephrotic syndrome, multiple myeloma or other kidney diseases, such as renal toxic substance damage, Fanconi syndrome.
(two) pathogenesis
Normal renal tubules have a strong reabsorption potential for sugar. Under physiological conditions, there is only a very small amount of glucose excretion in the urine (<1.0g/24h). Clinical routine examination of urine glucose is negative (2.22mmol/L or more positive), without interference When factors are involved, the ability of the kidney to resorb sugar depends on the number and capacity of the renal tubular epithelial cell reabsorption vector. The clinically often has the maximum tubular glucose reabsorption (MTG) and renal sugar. Threshold two indicators measure the reabsorption of glucose by the kidney. MTG actually refers to the total amount of glomerular filtration glucose per unit time (the glomerular filtration rate) when the blood glucose concentration is much higher than the renal glucose threshold. From the difference between the rate of urine glucose excretion (the product of urine sugar concentration and urine volume), MTG is the product of the maximum reabsorption rate of a single tubular glycoside and the total number of nephrons. Therefore, MTG is clearly affected by the total number of nephrons and individual tubular function.
In addition, the reabsorption rate of sodium ions can be used as an interference factor for MTG. The normal human MTG is 250-375 mg/min. Men are higher than females. Children are the same as adults after correction for body surface area, but the elderly are lower. The renal sugar threshold is Refers to the initial blood glucose concentration that can cause diabetes after the blood sugar gradually rises. The size of the renal sugar threshold is not only related to the ball-tube balance function of a single nephron, but also to the consistency of the sugar reabsorption threshold of each kidney unit of the whole kidney. The overall renal sugar threshold actually reflects the renal sugar threshold of the part of the nephron that has the worst re-absorption of sugar function. The normal human sugar threshold is 8.88 mmol/L (160-190 mg/dl), and the GFR is 125 ml/min. At this time, the sugar load in the filtrate is: (160 ~ 190) mg / dl × 125ml / min = 200 ~ 237mg / min, this value is obviously smaller than MTG, the phenomenon is related to the following factors: sugar and reabsorption Affinity of the carrier, heterogeneity of renal unit reabsorption capacity, decreased ratio of proximal tubule surface area to glomerular filtration membrane area, ball-tube imbalance; decreased number of renal retortors for glucose reabsorption transporters, or altered affinity Or gradient barriers. The accumulation of glucose in different concentrations of renal tubular cells is reduced; the permeability of the tubular membrane to glucose is reduced, and in addition, the intestinal absorption of glucose is also impeded.
Prevention
Pediatric renal diabetes prevention
There is nothing that needs to be paid too much attention, mainly prevention, and timely detection of timely treatment.
Complication
Pediatric renal diabetes complications Complications malnutrition dehydration
Can be complicated by dehydration and malnutrition, hypoglycemia and so on. Other secondary renal glycosuria may have different complications depending on the primary disease. Childhood cases also have hypoglycemia symptoms due to excessive urine sugar, but generally do not change to metabolic diabetes. In a few cases, there may be more than three symptoms, such as polydipsia, polyuria, and more food. The sugar is often continued, and the amount of urine sugar is generally <30g. /24h, while fasting blood glucose is normal, glucose tolerance test is normal, urinary glucose loss can occur ketosis, urinary ketone positive, easily misdiagnosed as diabetes, but it should be noted that renal glucosuria can be a prelude to diabetes, in renal glucosuria Based on the development of true diabetes.
Symptom
Renal glucosuria symptoms in children Common symptoms Kidney glucosuria Fasting hypoglycemia Diarrhea Dehydration Kidney damage Appetite abnormality
Generally asymptomatic, occasionally functional hypoglycemia, mostly found during routine examinations.
1. Primary renal glucosuria
It is a genetic reversal of renal tubular obstruction caused by genetic factors. There are two clinical diseases: intestinal glucose-galactose malabsorption syndrome and benign familial renal benign familial renal. Glucosuria), no specific clinical manifestations of primary renal glucosuria, occasionally found in urine test, fasting blood glucose is normal, glucose tolerance test is also normal, children generally have no significant effect on growth and development, may be due to compensatory appetite hyperactivity , added to the loss of urine sugar.
(1) Small intestine glucose-galactose malabsorption syndrome
It is a congenital defect of galactose and glucose transport in jejunum and renal tubular epithelial cells. It is mainly caused by intestinal malabsorption, watery diarrhea in primary children, dehydration and malnutrition. A large amount of galactose can be detected in the stool. Healing, kidney disease is mild, and only seen in homozygous zygotes.
(2) benign familial renal glycosuria
For autosomal dominant hereditary diseases, it can be divided into two types: type A is a decrease in renal sugar threshold and MTG, and can have Fanconi syndrome; type B only has a decrease in renal sugar threshold, and the degree of diabetes Depending on the person, the most severe cases have almost no absorption of glucose in the renal tubules. O-type renal glucosuria is the most serious condition in type A, and the above two indicators vary in mild to moderate patients. Therefore, it is not necessary to For type A and type B, Oemar first reported a case of type O renal glucosuria in 1987. The daily urine glucose excretion was as high as 136-160 g/1.73 m2, and the blood glucose was 75-105 mg/dl (4.16). ~5.83mmol/L), the glomerular filtration rate of inulin removal rate was 148-153ml/(min·1.73m2), when the blood glucose concentration was maintained at 72-82mg/dl (4.00~4.55mmoL/L), glucose The clearance rate was 112-160ml/(min·1.73m2), and the sugar clearance rate was almost equal to the glomerular filtration rate. After intravenous glucose administration, the blood glucose concentration was increased to 261-342mg/dl (14.4818.98mmol/L). The blood glucose clearance rate is unchanged. Bagga is equal to another O-type renal glucosuria reported in 1991. The younger brother of the family members is a severe type A kidney. Urine, mother type A mild renal diabetes, father renal tubular reabsorption of glucose normal.
2. Secondary renal glucoseuria
Secondary patients are mainly primary manifestations, more common than primary renal glucosuria, secondary to chronic interstitial nephritis, multiple myeloma and other organic kidney damage, most tetanus patients have a sexual Renal glucosuria, Rezaian reported that 63 of 63 patients with normal blood glucose had renal glucosuria (52%). All patients had disappeared during the recovery period of primary disease. Renal glucosuria in pregnant women is another common clinical phenomenon. Drexel et al found that 234 (66%) of 352 pregnant women had renal glucose urinary dysfunction, and they also found that the mechanism of renal glucosuria in pregnant women was the same as that of familial renal glucosuria type A, and the MTC decreased to normal levels. About half, and the renal sugar threshold was also significantly reduced. Chen et al found that there were 291 cases of renal glucosuria among 17229 single-pregnant women, of which the incidence of non-maternal renal glucosuria was 2.8%, and the maternal rate was 1.1%. There is a significant difference between the two groups. The incidence of precocious puberty in patients with persistent renal glucosuria is as high as 25.0%. It is worth noting that women with late pregnancy and childbirth are accompanied by varying degrees of lactoseuria, which is a physiological phenomenon and renal grape. There is a qualitative difference in urine, some secondary renal glucosuria with other renal tubular dysfunction, urine glucose positive, glucose, can be slightly increased after meals, daily urine sugar <20 ~ 30g; normal or low blood sugar; The glucose tolerance curve is normal and may have a positive family history; no history of diabetes and kidney disease.
Examine
Pediatric renal diabetes test
Urine test
Urinary glucose excretion can be significantly increased.
2. Blood sugar
Fasting blood glucose was normal 75 ~ 105mg / dl (4.16 ~ 5.83mmol / L), glucose tolerance test is also normal.
3. Glomerular filtration rate
The inulin clearance rate is increased, and even the sugar clearance rate is almost equal to the glomerular filtration rate.
4. stool examination
Small intestine glucose-galactose malabsorption syndrome In the stool of newborn children, a large amount of galactose can be detected, and the feeding of fructose can be cured. B-ultrasound and X-ray examination are routinely performed.
Diagnosis
Diagnosis and diagnosis of renal glycosuria in children
diagnosis
1. Qualitative diagnosis
First, we should rule out the overflowing diabetes and non-glucose glucosuria caused by hyperglycemia, urinary resorcinol test positive in fructose, urinary urinary dihydroxytoluene hydrochloride positive, lactose urinary, galactose urinary and mannose glucoside Paper chromatography can be determined.
2. Judgment of the severity of renal diabetes
The usual practice is to determine the amount of urine glucose excretion in 24h. When the blood glucose is at physiological concentration, the more urine glucose excretion in 24h, the worse the reabsorption of renal tubular sugar; but the amount of urine glucose excretion per unit time is also affected by glomerular filtration. The effect of over-rate, so in the case of renal dysfunction, 24h urinary glucose excretion can not reflect the severity of renal glucosuria, a more reasonable way to determine the glomerular filtration rate and glucose clearance rate, and then calculate glucose clearance The ratio of the rate to the glomerular filtration rate, the higher the ratio indicates that the renal tubular glucose reabsorption function is worse, and the ratio is close to 1.0 in O-type renal glucosuria.
3. The cause diagnosis of renal diabetes
Secondary renal diabetes, such as Fanconi syndrome, Löwe syndrome and other clinical manifestations of kidney disease, the characteristics of the underlying disease provide an important basis for clinical diagnosis, primary renal The small intestine glucose-galactose malabsorption syndrome in diabetes can also be diagnosed according to its unique clinical manifestations. The diagnosis of benign familial renal diabetes is important for family history investigation.
Differential diagnosis
Need to be differentiated from kidney disease such as diabetes, Fanconi syndrome, Lowe syndrome, and non-glucose diabetes (glucoseuria, fructoseuria, lactoseuria, galactoseuria).
Diabetic nephropathy
It is a specific change of glomerular sclerosis on the basis of diabetes glucose metabolism disorder. In addition to the characteristics of diabetes such as polyuria, polydipsia, polyphagia, hyperglycemia, urine glucose positive, and impaired glucose tolerance, it also has protein. Urine, edema, hypertension and renal insufficiency, poor prognosis.
2. Steroid diabetes
It is due to the long-term use of adrenocortical hormone-induced secondary glucose metabolism abnormalities (hyperglycemia, urinary glycemic patients) renal function deterioration, reduction or discontinuation of corticosteroids, glucose metabolism returns to normal, prognosis is related to the nature of renal pathological changes Diffuse type of diabetic nephropathy is more likely to progress to uremia.
