Diabetes insipidus in children

Introduction to diabetes insipidus in children Diabetes insipidus (diabetesinsipidus) is caused by hypothalamic and pituitary causes of insufficient secretion and release of antidiuretic hormone (ADH), or renal polydipsia, polydipsia, polyurea and low specific gravity urinary clinical syndrome caused by defects in ADH. Patients with growth hormone deficiency have been reported with diabetes insipidus. basic knowledge The proportion of illness: 0.0005%-0.0007% Susceptible people: children Mode of infection: non-infectious Complications: renal insufficiency

Causes of diabetes insipidus in children

(1) Causes of the disease

Causes of diabetes insipidus is more common, generally divided into primary diabetes insipidus, secondary diabetes insipidus and hereditary diabetes insipidus, clinically according to the site of the disease can be divided into central diabetes insipidus and kidney There are two major categories of diabetes insipidus.

1. Central diabetes insipidus (ADH deficiency diabetes insipidus) Central diabetes insipidus caused by ADH deficiency, lesions in any part of the hypothalamus and pituitary can cause diabetes insipidus, which is due to hypothalamic supraoptic nucleus and paraventricular The most common cause of neuronal dysplasia or degenerative lesions in the nucleus, accounting for about 50% in previous reports. Some central diabetes insipidus is actually secondary to intracranial tumors, often with urinary collapse. Symptoms, tumor symptoms appear many years later, so must be highly vigilant, regular head imaging examination, hereditary (familial) diabetes insipidus is rare, only about 1%, usually autosomal dominant inheritance, some people think It is caused by the decrease or even the lack of cells producing ADH. Some of the central diabetes insipidus is caused by various intracranial lesions, such as tumors (more common craniopharyngioma and pineal tumors, accounting for 70%). %), granuloma, inflammation, craniocerebral trauma, cerebrovascular disease, surgery or cranial radiotherapy can cause diabetes insipidus, which is caused by tumors in children at least 30%, neonatal hypoxemia, lack Hypoxic encephalopathy can cause diabetes insipidus in childhood.

2. Nephrogenic diabetes insipidus Nephrogenic diabetes insipidus is a hereditary disease, X is associated with recessive inheritance, a few are autosomal dominant, because the centrally secreted ADH has no biological activity or abnormal ADH receptor ADH can not bind to renal tubular receptors or defects in renal tubules, etc., resulting in low sensitivity or resistance of distal renal tubules to ADH, resulting in diabetes insipidus. This type can also be caused by various diseases such as pyelonephritis and renal tubules. Acidosis, tubular necrosis, kidney transplantation and azotemia cause damage to the renal tubules.

(two) pathogenesis

The 9-peptide ADH was synthesized from the suprachiasmatic nucleus of the hypothalamus and the paraventricular nucleus. The neuropeptide secreted down the axon to the pituitary gland. The normal human ADH increased in the late night and morning, and was lower in the afternoon. The daily secretion of ADH is 20-100U/ml. The secretion of ADH is mainly affected by the osmotic pressure and blood volume of extracellular fluid. The normal human osmotic pressure is 50-1200mmol/L. The human body keeps the plasma osmotic pressure through the secretion of ADH. 280 ~ 290mmol / L, normal people in dehydration, plasma osmotic pressure increased, blood volume decreased, the former stimulated the osmotic pressure receptor located in the supraoptic nucleus, so that ADH secretion increased, urine output decreased, the latter caused hypothalamic thirst The center is excited, the amount of drinking water increases, and the plasma osmotic pressure returns to the normal state. On the contrary, when the body has too much water, the plasma osmotic pressure decreases, the blood volume increases, the secretion of ADH and the excitability of the thirst center are inhibited, and the amount of urine increases. Drinking water stops, plasma osmotic pressure returns to normal, and those with diabetes insipidus, due to insufficient secretion of ADH or renal tubular response to ADH, water can no longer be absorbed, so a large amount of urination, thirst, Xing The thirst center, a large amount of drinking water, so that the plasma osmotic pressure can basically maintain the high limit of normal osmotic pressure, the plasma osmotic pressure of most patients with diabetes insipidus is slightly higher than normal people, for premature infants with thirst center immature, newborn, Although infants and young children urinate a lot, but can not drink more, there is persistent hypernatremia, resulting in hypertonic dehydration.

Prevention of diabetes insipidus in children

The cause of this disease is primary and secondary. The cause of primary disease is unknown. The common causes of secondary disease are tumor, trauma, infection, etc. Therefore, it is very important to prevent the cause of secondary diabetes insipidus. Discovered, early treatment related causes.

Focus on the prevention of secondary NDI, because a considerable part of it is iatrogenic, clinical should be vigilant. For the prevention of CDI, it is necessary to refer to other birth defects. In order to reduce the incidence of this disease, prevention should be carried out from pre-pregnancy to prenatal, and strengthen the consultation of genetic diseases.

Pre-marital medical examination plays an active role in preventing birth defects. The size of the effect depends on the examination items and contents, including serological examination (such as hepatitis B virus, treponema pallidum, HIV), reproductive system examination (such as screening for cervical inflammation), General physical examination (such as blood pressure, electrocardiogram) and ask about the family history of the disease, personal medical history, family history and so on.

Pregnant women should avoid harmful factors as much as possible, including away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile harmful gases, toxic and harmful heavy metals. Systemic birth defect screening is required during antenatal care during pregnancy, including regular ultrasound, serological screening, and, if necessary, chromosomal examination. Once an abnormal result occurs, it is necessary to determine whether to terminate the pregnancy; the safety of the fetus in the uterus; whether there is sequelae after birth, whether it can be treated, and how the prognosis is. Take practical and feasible treatment measures.

Before the drug treatment, supply sufficient water, especially newborns and small babies, to avoid dehydration and hypernatremia. Tumor patients should decide on surgery or radiotherapy according to the nature and location of the tumor. For those with mental polydipsia syndrome, look for the mental factors that lead to polydipsia and polydipsia, and provide symptomatic guidance for psychotherapy.

Pediatric diabetes insipidus complications Complications, renal insufficiency

Failure to drink water properly can cause hypertonic dehydration symptoms such as fever, constipation, and weight loss. In severe cases, convulsions or coma can occur. It is still possible to have growth disorders, hydronephrosis, ureteral dilatation, and even renal insufficiency. There are complications such as renal ureteral hydrops and bladder dilatation.

1. Diabetes insipidus with hypopituitarism

Surgery, tumor and inflammation in the hypothalamus or pituitary can cause diabetes insipidus and pituitary dysfunction, vascular lesions of postpartum pituitary necrosis, and can also damage the supra-nucleus pituitary system and cause diabetes insipidus and mat Han syndrome, diabetes insipidus and pituitary dysfunction, polyuria symptoms, urine osmolality is higher; because glucocorticoids and vasopressin antagonism, so when glucocorticoid deficiency, vasopressin deficiency The condition will be alleviated. In addition, when glucocorticoids and thyroxine are reduced, the excretion of urinary solute is reduced, and the symptoms of polyuria can be alleviated.

2. Diabetes insipidus with thirst sensation syndrome

This syndrome is a deficiency of vasopressin, and the feeling of thirst also decreases or disappears. The patient's kidney can not regulate the excretion of water normally. The patient does not have the thirst, and cannot increase the amount of drinking water at any time for the needs of the human body. Drink more, have severe dehydration and high blood sodium, body fluids are hypertonic, accompanied by hyperosmotic signs, headache, myalgia, tachycardia, personality changes, irritability, confusion, paralysis and even coma, with vasopressin The dosage is not easy to adjust during treatment, and it is easy to overdose and cause water retention. It is hypotonic or water poisoning. It can be treated with chlorpropamide, 250mg/d, the urine volume can be reduced, and the function of thirsty center can be improved.

3. Diabetes insipidus combined with pregnancy

Diabetes in patients with diabetes insipidus with pregnancy, the condition of diabetes insipidus can be aggravated, because the secretion of adrenal cortex hormone in pregnant women increases, it can antagonize the antidiuretic effect of vasopressin, or inhibit the secretion of vasopressin, in addition, pregnancy Adrenal cortex hormones and thyroid hormones increase, urinary solute excretion increases, so that the amount of urine increases, throughout the pregnancy, especially in the middle, the patient's need for vasopressin increased, often also make the condition of diabetes insipidus worse. Diabetes insipidus is relieved after childbirth.

Symptoms of diabetes insipidus in children Common symptoms Urine collapse, polyuria, polydipsia, increased intracranial pressure, irritability, urinary constipation, ureteral dilatation, dehydration, hydronephrosis

Patients with diabetes insipidus have more men than women, and can develop from any number of months after birth to any age in adolescence. It is more common in childhood, and more sudden onset in older children, but also progressive.

1. Polyuria or enuresis is often the earliest symptom found by parents. The number of urination and urine output is increased. The daily urine volume is more than 4L, and more than 10L (more than 300~400ml/kg per hour or hourly). 400ml/m2, or more than 3000ml/m2 per day), morning urine color can also be light as water.

2. Drinking more in the baby's performance like drinking water than eating milk, children generally like to drink cold water, even in the winter also love to drink cold water, drinking water is roughly equal to the amount of urine, if you do not drink water, polydipsia is unbearable, but the amount of urine does not decrease .

3. Other children have no other symptoms because they can drink enough water. If the baby can't drink water properly, they often have irritability, restless sleep, fever, constipation, weight loss and dry skin. In severe cases, convulsions can occur. , coma, long-term polydipsia can lead to growth disorders, hydronephrosis, ureteral dilatation, and even renal insufficiency, intracranial tumors cause secondary diabetes insipidus, in addition to diabetes insipidus may have increased intracranial pressure, such as Headache, vomiting, visual impairment, etc. Renal diabetes insipidus is mostly male, with a family history, and the age of onset is earlier.

Examination of diabetes insipidus in children

1. Urine specific gravity The urine specific gravity of patients with diabetes insipidus is more than 1.001 to 1.005.

2. Blood and urine osmotic pressure The urine osmotic pressure of patients with diabetes insipidus is 50-200mmol/L, and the blood osmotic pressure is normal or increased.

3. Blood and kidney function and electrolyte examination If there is kidney involvement, there may be different degrees of renal dysfunction. People with diabetes insipidus usually have normal urine routine, urine sugar is negative, and blood sodium is normal or slightly higher.

4. ADH measures the concentration of ADH in the blood of patients with central diabetes insipidus. Because the measurement method is complex, the specificity and sensitivity are not high, so it is necessary to observe the dynamics, the concentration of ADH in blood circulation is generally 10U/ml.

5. Special laboratory examination of diabetes insipidus

(1) water-deprivation test: mainly used to identify diabetes insipidus and mental polydipsia, starting at 8 am, urinating before the test, measuring body weight, urine volume, urine specific gravity and urine osmotic pressure, Blood sodium and plasma osmotic pressure were measured. Drinking water was 20ml/kg within 1h, then banned for 6-8h, urine was collected every hour, urine volume, urine specific gravity and urine osmotic pressure were collected. A total of 6 times were collected. At the end of the experiment Blood sampling, blood sodium and plasma osmotic pressure, if the patient urinates a lot, although the ban is less than 6h, and the weight has decreased by 3% to 5%, or the blood pressure is significantly reduced, immediately stop the test, normal people do not ban water Severe dehydration symptoms, blood osmotic pressure changes little, urine output decreased significantly, urine specific gravity exceeded 1.015, urine osmotic pressure exceeded 800mmol / L, urine osmotic pressure and plasma osmotic pressure ratio was greater than 2.5; urine volume in patients with complete diabetes insipidus No significant reduction, specific gravity <1.010, urine osmotic pressure <280mmol/L, plasma osmotic pressure>300mmol/L, urine osmotic pressure is lower than blood osmotic pressure; and partial urinary insipidus plasma osmotic pressure highest value <300mmol/L; The specific gravity is up to 1.015, the urine osmotic pressure is up to 300mmol/L, or urine infiltration The ratio of transfusion to blood osmotic pressure is greater than or equal to 2, indicating that the amount of ADH secretion is normal and is mentally polydipsia.

(2) banned drink combined with vasopressin test: for the identification of central diabetes insipidus and renal diabetes insipidus, first water ban, urine once every hour, urine specific gravity and osmotic pressure, two consecutive urine infiltration When the pressure difference is <30mmol/L, the water-soluble vasopressin is injected 0.1U/kg, and the urine specific gravity or urine osmotic pressure is measured every hour after injection for 2 to 4 times. After the injection of vasopressin in normal people, the urine osmotic pressure Can not be increased after the ban, a small increase of no more than 5%, and sometimes a little lower, the central dialysis syndrome, banned drink, urine osmotic pressure can not be significantly increased, but after injection of vasopressin, urine osmotic pressure Increase, and exceed the plasma osmotic pressure, urine output is significantly reduced, the specific gravity of 1.015 or more even 1.020, urine osmotic pressure of more than 300mmol / L; partial central diabetes insipidus patients, urine osmotic pressure can be increased after drinking, can be Exceeding the plasma osmotic pressure, the osmolality can be further increased after the injection of vasopressin; if the vasopressin is poorly reacted, the urine volume and specific gravity, and the urine osmotic pressure have no significant change, it can be diagnosed as renal diabetes insipidus.

Head MRI examination can understand the morphological changes of the hypothalamus and pituitary, exclude intracranial tumors, and those with dwarfism can find that the pituitary volume becomes smaller. If necessary, the head MRI should be repeated regularly. After the skull MRI nerve pituitary is destroyed, the image is in the image. The highlight of the pituitary gland disappears, and the high signal area of the pituitary gland disappears in general patients with diabetes insipidus.

Diagnosis and diagnosis of diabetes insipidus in children

diagnosis

For children with polydipsia and polyuria, it is very important in the medical history to drink water at night. The amount of intake and output should be recorded. When drinking more than 2L/m2 per day, it is a pathological phenomenon. Learn about other disease history, family history, growth. History, central nervous system symptoms and signs, etc., to suggest possible causes of the disease.

Pathological polydipsia and urine should be measured plasma osmotic pressure and blood Na, K, Cl, Cr and BUN and urine analysis, urine osmotic pressure, urine specific gravity, urine sugar, plasma osmotic pressure> 300mOsm / kg, urine osmotic pressure <300mOsm /kg, can be diagnosed as diabetes insipidus, when the plasma osmotic pressure is >270mOsm/kg, the water limit test should be carried out, such as plasma osmotic pressure>300mOsm/kg, urine osmotic pressure above 10h and always <600mOsm/kg should be considered Diabetes insipidus, such as urine osmotic pressure > 600mOsm / kg and stable for more than 1h can rule out diabetes insipidus, such as weight loss in the water limit test, more than 5%, blood Na > 150mmol / L, there is significant dehydration and blood volume reduction and When the blood pressure drops, the water restriction test should be terminated. After subcutaneous injection of pituitin 1U/m2 (1ml=5U), the urine is discharged every 15 minutes. The urine volume is obviously reduced, the urine specific gravity and urine osmotic pressure are increased. Can be more than doubled in 1h, can be diagnosed as central diabetes insipidus.

After the diagnosis of central diabetes insipidus, the cause should be further investigated. It is necessary to perform MRI examination of the hypothalamus and pituitary to exclude intracranial lesions.

For the partial AVP deficiency, the tolerance to water limitation is better. Although the urine osmotic pressure can rise more than >600mOsm/kg, the urine osmotic pressure/plasma osmotic pressure is still >1, when it is differentiated from renal diabetes insipidus. The latter has no response to pituitary vasopressin, and can also measure plasma AVP concentration, which is low in partial central diabetes insipidus and high in renal diabetes insipidus.

Differential diagnosis

Those with diabetes insipidus should actively seek the cause and observe whether there are other hormone deficiency in the pituitary.

1. syndrome of inappropriate antidiuretic hormone (SIADH) SIADH is often iatrogenic in children, some due to improper infusion, excessive hypotonic fluid input, SIADH can occur in intracranial lesions such as Meningitis, brain tumors, head trauma, etc., children with tuberculous meningitis may have increased AVP secretion with hyponatremia, indicating a serious condition and poor prognosis, when the second stage of hypothalamic and pituitary surgery can occur increased AVP secretion Children with dDAVP in the treatment of central diabetes insipidus or enuresis may also occur, other rare causes can be seen in lung disease, lung obstruction, mechanical hyperbaric ventilation and some drugs such as carbamazepine and chemotherapy drugs.

The main clinical manifestations of SIADH are central nervous system symptoms such as vomiting, headache, etc., which may be fatigued at an early stage, mainly due to excessive water reabsorption of kidney water, excessive fluid volume, water and hyponatremia, plasma infiltration. The pressure is reduced, and the hypertonic urine and urinary sodium excretion are increased. When SIADH is chronically hyponatremia, there is no obvious symptom. The blood Na<120mmol/L. If the hypotonic fluid is not properly input, the blood sodium is faster. Below 130 mOsm/kg, convulsions and coma occur, especially in children of small age, with normal renal function.

2. Renal diabetes insipidus Renal diabetes insipidus is caused by AVP resistance, hereditary and acquired, hereditary disease is less and the condition is heavier, and children are more common than adults.

(1) Congenital X-linked renal diabetes insipidus: is a dominant hereditary, mostly a boy's disease, the disease is AVP V2 receptor gene mutation, V2 receptor is activated in the kidney adenyl cyclase, its receptor The defect is abnormality of G protein- unit. Because AVP resists the kidney to produce a large amount of hypotonic urine, the urine osmotic pressure is often 50-100 mOsm/kg. This disease often occurs during weaning after birth, and there is obvious polydipsia. Urine, thirst is difficult to meet, fever, vomiting and dehydration, often misdiagnosed as infection, children prefer to drink water and refuse to eat high-calorie solid food, such as failure to timely diagnosis and treatment, children with growth disorders, inadequate feeding often repeated Dehydration occurs, causing different degrees of intelligent backwardness. X-ray skull slices often show calcification of the frontal lobe and basal ganglia. The cause of calcification is related to severe dehydration. It may also be due to AVP resistance, blood AVP concentration, AVP V1. And V3 receptors are normal, causing brain calcification through some unique effects. Larger children automatically reduce food intake due to excessive nighttime urine, leading to malnutrition causing growth disorders, and due to long-term heavy drinking and discharge. Urine, renal pelvis and ureter obvious expansion of hydrocephalus and bladder may occur.

(2) Congenital autosomal recessive renal diabetes insipidus: This disease is aquaporin-2 gene mutation in the protein of the renal tubule epithelial cells in the water channel, this mutation damages the permeability of the luminal membrane to water, making the kidney The filtrate in the small tube can not be reabsorbed, causing polyuria. An aquaporin-2 in the urine of aquapolin-2 mutant has been reported to increase, and aquaporin-2 can be used for the identification of central diabetes insipidus.

(3) Acquired diabetes insipidus: more common, mostly due to the effect of lithium or tetracycline on the stimulation of cAMP by AVP. About 50% of patients receiving lithium can damage the urine concentration function, and 10% to 20% develop clinical diabetes insipidus. And often accompanied by decreased glomerular filtration rate, lithium may damage AVP stimulate adenosine cyclase production, so that the aquaporin gene mRAN expression in the renal collecting duct, resulting in polyuria.

Tetracycline is used to treat the renal water transport function of renal tubular epithelial cells. Other polycystic kidney disease and sickle cell disease also impair kidney enrichment. Reduced protein and sodium intake can also cause diabetes insipidus.

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