Nephrogenic diabetes insipidus

Introduction to renal diabetes insipidus Renal diabetes insipidus (nephrogenicdiabetesinsipidus) is a disease of renal tubular dysfunction of water reabsorption, manifested by polyuria, polydipsia and persistent hypotonic urine. The cause may be hereditary and secondary, hereditary is a hereditary tubular disease, also known as hereditary or primary anti-pituitary vasospasm, also known as familial renal diabetes insipidus . Secondary can occur in a variety of chronic kidney diseases (such as obstructive nephropathy, interstitial nephritis, chronic pyelonephritis, hypercalcemia, potassium loss nephropathy, renal tuberculosis, renal medullary cystic disease, etc.), multiple Myeloma, renal amyloidosis, drug damage (such as dimecycline, methoxyflurane, vincristine). Acquired patients are also known as secondary or incomplete anti-ADH due to the anti-ADH effect of kidney and extra-renal diseases and/or the hyperosmotic state of the medullary fluid of the kidney, which affects the concentration of urine. Diabetes insipidus. basic knowledge The proportion of sickness: 0.00015% - 0.0002% Susceptible people: no special people Mode of infection: non-infectious Complications: chronic renal failure hyperosmolar dehydration hypernatremia

Cause of renal diabetes insipidus

(1) Causes of the disease

Renal diabetes insipidus is caused by abnormalities of congenital genetic factors and acquired, that is, acquired factors. Common secondary causes are:

Disease factors (55%):

Chronic renal failure, decreased concentrating function. Electrolyte disorder, hypokalemia, high blood calcium. Diuresis after urinary tract obstruction is relieved. Acute renal failure diuretic period. Paroxysmal hypertension. Systemic disease sickle cell anemia, Sjogren's syndrome, amyloidosis, Fanconi syndrome, sarcoidosis (sarcoidosis), renal tubular acidosis, light chain nephropathy.

Drug factors (35%):

Lithium drug, dexamethasone (nor-methanomycin), colchicine, vinblastine, methoxyfluoride, anesthetic, toluenesulfonamide, chlorpropamide, amphotericin B, gentamicin, furosemide, Etaniic acid, osmotic diuretics, angiographic contrast agents, cyclophosphamide, etc.

Other factors (5%):

Abnormal eating and drinking water, less sodium intake, less protein intake.

(two) pathogenesis

Renal diabetes insipidus is resistant to ADH (antidiuretic hormone) in the distal and collecting duct epithelium, and symptoms of diabetes insipidus appear. Plasma ADH levels are higher than normal. Injection of ADH does not increase urinary cAMP, so it is considered critical. In the renal tubular can not produce cAMP under the action of ADH, hereditary renal diabetes insipidus is sexually dominant, and the abnormal X chromosome is transmitted by the father, child health, female disease, XY xxXx Xx xY xY; Children can get sick, Xx xYXx XY xx xY, male children are more serious than females, because male patients do not have normal X chromosome, while female patients have an abnormal X chromosome but have a normal X chromosome. Against abnormal chromosomes, hereditary renal diabetes insipidus is caused by chromosomal abnormalities. The distal renal tubules and collecting ducts are not sensitive to vasopressin, resulting in insufficient cAMP in the renal tubular epithelial cells (or insufficient receptors, other substances and receptors). The body produces competitive inhibition and decreased affinity, or cAMP acts on the luminal side membrane, causing impaired function of water permeability. At present, molecular mechanisms for the occurrence of renal diabetes insipidus have been revealed at the genetic level. It is thought to be caused by a defect in the V2 receptor (V2R) defect on the pericardium of the renal collecting duct or a tubular water channel (a type of membrane glycoprotein selectively permeable to water). Secondary The primary disease destroys the hypertonic state of the renal medulla, causing dysfunction of the renal tubular urinary tract, but still has some response to vasopressin.

Renal diabetes insipidus prevention

Active treatment of primary disease, symptomatic treatment of complications, early diagnosis and early treatment for severe symptoms, to prevent electrolyte imbalance caused by acute dehydration, the disease focuses on the prevention of secondary NDI, because a considerable part of it is iatrogenic, clinical Be alert.

Renal diabetes insipidus complications Complications chronic renal failure hyperosmolar hypernatremia

1. Bladder bloating, ureteral dilatation and hydronephrosis and chronic renal failure, the cause of the above diseases is due to the long course of disease, caused by excessive urine output.

2. Hyperosmolar dehydration and electrolyte imbalance, such as hypokalemia or hypernatremia.

3. Growth and developmental disorders.

Symptoms of renal diabetes insipidus Common symptoms Urine collapse, hypernatremia, water loss, convulsions, polydipsia, dehydration, high fever, postpartum urination frequency or...

1. Polyuria and polydipsia: The clinical manifestation of this disease is that the congenital NDI can have polyuria and polydipsia symptoms at birth, and it is characterized by excessive amniotic fluid before birth.

2. hypotonic urine: the specific gravity of urine often lasts less than 1.005, or the urinary exudation is less than 200mOsm / (kg · H2O), given solute diuretic, can only reach 280 ~ 300mOsm / (kg · H2O) with plasma isotonic Degree.

3. Hyperosmolar dehydration and insufficient blood volume: Because infants and young children can not express thirst, prone to hyperosmolar dehydration and insufficient blood volume, can lead to central nervous system symptoms and infant mental development disorders, such as serious water loss can lead to death, When dehydration is caused by factors other than CDI and NDI, the urine should be concentrated urine. Therefore, infants with dehydration and dilute urine should be alert to the possibility of this disease. Adult patients are not restricted by water or have a central nervous system with osmolarity. Severe hypertonic dehydration can occur.

4. Growth retardation: seen in congenital NDI.

5. Mental retardation and psychological abnormalities: It is generally believed that mental retardation is one of the main complications of congenital NDI. Less than half of the patients have varying degrees of IQ, distraction and psychological disorders. Most patients' IQ can be normal. Level.

6. urinary tract water: patients with this disease due to long-term urinary flow, no urinary tract obstruction can also occur urinary tract water, long-term urinary tract water can induce or aggravate chronic renal failure.

7. Brain tissue calcification: This disease is often accompanied by intracranial calcification, and its incidence increases with the prolongation of the disease course. It is related to the quality control of polyuria and polydipsia, which can cause seizures.

8. Hyperprostaglandin E syndrome: The excretion of urinary prostaglandin E is significantly increased, both congenital and acquired. Controlling this phenomenon can alleviate the clinical manifestations of NDI.

9. The manifestations of primary disease: the clinical manifestations of acquired NDI with underlying diseases and the corresponding renal pathological changes, some patients with mild symptoms, incomplete NDI, drug-induced NDI in addition to patients who have long-term use of lithium salts, Other drugs cause NDI to be seen mainly in critically ill patients in the ICU who receive multiple drug treatments, especially antibiotics and antineoplastic agents.

10. Hereditary: About 90% occur in males, usually in the short after birth, and only after the age of 10, the main symptoms are polyuria (low specific gravity urine), polydipsia, polydipsia, growth and development disorders, etc. Neonates or critically ill patients often have high fever, convulsions, hypernatremia and other clinical symptoms due to dehydration. This type of symptoms can be gradually reduced with age, such as long-term dehydration, extracellular fluid infiltration, damage to brain cells, Cause mental retardation.

11. Secondary: First, the symptoms of the primary disease will be manifested. After the occurrence of polyuria, polydipsia, dehydration, blood concentration and other symptoms and signs, laboratory tests may have hypernatremia, hyperchloremia and urine permeation. Pressure drop (less than 200mmol / L) and so on.

Examination of renal diabetes insipidus

1. Urine examination: daily urine volume increased significantly, and the urine specific gravity decreased (1.001 ~ 1.005), urine osmotic pressure was more than 150 ~ 180mmol / L, vasopressin test did not respond ("incomplete performance" can be There is a partial reaction).

2. Blood test: due to blood concentration, plasma osmotic pressure increases, extracellular fluid is hyperosmotic. When plasma osmotic pressure is >280mOsm/L, hemoglobin and hematocrit increase, blood sodium, blood chlorine rise, blood sodium >150mmol / L, late urea hydrogen and creatinine can be increased.

3. Exogenous injection of vasopressin is ineffective, urinary cAMP solution does not increase, hypertonic saline test does not respond, water-free test can be used to distinguish between heavy, mental, and renal diabetes insipidus.

Routine imaging and B-ultrasound can be found, too much amniotic fluid at birth, hydronephrosis, hydronephrosis, ureteral hydrops, bladder dilatation, etc. Brain CT can be found in brain CT examination, EEG can be detected Abnormal waves or epileptiform discharges were found.

Diagnosis and diagnosis of renal diabetes insipidus

diagnosis

1. Typical cases: According to the positive family history and laboratory examination and clinical manifestations can be diagnosed, the main symptoms of congenital renal diabetes insipidus such as polydipsia, polydipsia, polydipsia, low urine, no response to ADH, young children such as Repeated symptoms such as polydipsia, vomiting, fever, water loss and growth and development disorders. After other reasons are excluded, the disease may be considered. In the case of water loss, the urine is still in a low-tension state and has obvious value for diagnosis.

2. Atypical cases: congenital male symptoms are more common, female patients generally have no obvious symptoms or only varying degrees of urinary concentrating dysfunction, such as repeated dehydration, polydipsia, vomiting, fever, convulsions and developmental disorders, Especially in the case of water loss, urine is still low-tension, which has certain value for diagnosis. Patients with secondary diabetes insipidus often have clinical manifestations of primary disease, and symptoms of diabetes insipidus are mild, which can be diagnosed according to medical history. .

Differential diagnosis

Renal diabetes insipidus needs to be differentiated from pituitary diabetes insipidus, neurological polydipsia and diabetes.

1. Pituitary diabetes insipidus:

The disease is caused by the lack of antidiuretic hormone, low blood ADH level, low urinary cAMP, significant improvement in polydipsia after injection of vasopressin, increased urinary cAMP, increased osmolality, and pituitary diabetes insipidus more than youth. The onset of the disease, sudden onset, polyuria, heavier symptoms of polydipsia, may have signs of hypothalamic-neuronal pituitary damage, good response to vasopressin test.

2. Spiritual polydipsia, polyuria:

Neurogenic polydipsia, polyuria occurs mostly in adult women, often has a history of trauma, first polydipsia after polydipsia and polydipsia, large fluctuations in urine volume and close relationship with mental factors, responding to vasopressin experiments The reaction to hypertonic saline is rapid, the plasma osmotic pressure is slightly reduced, and the urine volume can be naturally reduced without drinking water at night.

3. Diabetes:

Drinking too much, polyuria can also occur, but its elevated blood sugar and abnormal glucose tolerance can be identified with this disease.

For polydipsia, pituitary diabetes insipidus or renal diabetes insipidus or neuropathic polydipsia can be identified by measuring the urine osmotic pressure after water inhalation or injection of vasopressin.

The above test results showed that there was no significant change in urine osmotic pressure after normal blood test in patients with neurological polydipsia and renal diabetes insipidus and after injection of vasopressin, and urine penetration of two test results in patients with pituitary diabetes insipidus. There was a significant change in pressure, the latter being significantly larger than the former. Renal diabetes insipidus and neurological polydipsia were significantly different in urine osmotic pressure after water cessation. The former was low and the latter was high.

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