Diabetes insipidus in the elderly

Introduction to diabetes insipidus in the elderly Diabetes insipidus is caused by the lack of antidiuretic hormone (ADH) or the inability of the kidney to fight diuretic hormone, resulting in a decrease in the function of renal tubular reabsorption of water, which causes polyuria, polydipsia, polydipsia, low specific gravity urine and hypotonic urine. The majority of clinical syndromes are central diabetes insipidus caused by deficiency of vasopressin, part of the renal diabetes insipidus caused by renal tubular resistance to diuretic hormone reduction, and part of it is caused by excessive water intake. For primary polydipsia. basic knowledge The proportion of illness: 0.03% Susceptible people: the elderly Mode of infection: non-infectious Complications: hypothyroidism hyponatremia

The cause of diabetes insipidus in the elderly

Central diabetes insipidus (30%):

(1) Space-occupying lesions or invasive lesions in the hypothalamic-pituitary region: various benign or malignant neoplastic lesions, primary such as craniopharyngioma, germ cell tumor, meningioma, pituitary adenoma, glioma, Astrocytoma; secondary to lung or breast metastases, lymphoma, leukemia, etc., granulomatous or infectious or immune diseases such as sarcoidosis, histiocytosis, xanthoma, encephalitis or Meningitis (including tuberculosis, fungal), necrotic funnel-neurohypophysitis, etc., vascular or other diseases such as Sheehan syndrome, aneurysm, thrombocytopenic purpura, abnormal brain development or deformity.

These are the most important lesions in central diabetes insipidus, accounting for about one-third of central diabetes insipidus. More than 60% of these lesions are associated with varying degrees of pituitary function.

(2) Head trauma: Trauma is often accompanied by skull fracture, but there is also a history of not serious head trauma, and after the occurrence of urine collapse, MRI found that the pituitary stalk was interrupted, localized thinning, and diabetes insipidus occurred after foreign cranial injury. In a car accident, diabetes insipidus can occur several years later after a cranial trauma.

(3) iatrogenicity: surgery involving the hypothalamus is almost always complicated by different degrees of diabetes insipidus, and often has anterior pituitary dysfunction before surgery, in the case of Concord, the diabetes insipidus caused by pituitary tumor surgery is increasingly Increased, some reported that the diabetes insipidus caused by surgery has occupied the first place, more than half of patients with pituitary tumor surgery have transient temporary diabetes insipidus mostly disappear within 2 to 3 days, postoperative symptoms of diabetes incontinence do not reduce for more than 3 weeks It is likely to become a permanent diabetes insipidus.

Radiation therapy generally does not occur with clinical symptoms of diabetes insipidus, and more patients with radiation therapy are caused by tumor lesions of the pituitary-hypothalamus.

(4) Idiopathic: After careful examination, it was considered after excluding various intracranial lesions and systemic diseases. It has been found that there are paraventricular nucleus antibodies in the supra-nuclear and paraventricular nucleus neurons and circulating blood. Often onset in childhood, with less hypopituitarism.

(5) Familial: It is an autosomal dominant inheritance, and some genes that have been found to be mutated can have a family history.

Renal diabetes insipidus (20%):

(1) Familial: mostly sexually linked recessive inheritance, clinically occurring in male children, also have abnormal V2 receptor gene or aquaporin II gene or autosomal recessive inheritance.

(2) Acquired acquired: Many diseases or drugs in the clinic can affect renal tubular dysfunction, and diabetes insipidus disappears after the primary disease is cured, such as hypokalemia, hypercalcemia and diabetes. Such metabolic diseases; pyelonephritis, polycystic kidney disease and other kidney diseases; sickle cell disease or specific blood or blood vessel diseases; also lithium, dicycline and anesthetic methoxyflurane drugs.

Primary polydipsia (20%):

These patients are acquired for acquired reasons, such as habitual polydipsia or mental illness (schizophrenia or neurosis, decreased thirst threshold, etc.), in patients with abnormal thirst may have intracranial lesions, such as tuberculosis Sexual granuloma, sarcoidosis, tumor, vasculitis, etc., sometimes coincide with central diabetes insipidus.

Pathogenesis

Antidiuretic hormone, also known as arginine vasopressin (AVP), is a 9-peptide amino acid substance with a molecular weight of 1084. ADH is mainly secreted by the supra-nucleus, and is also secreted by the paraventricular nucleus, and then stored along the descending cellulose pathway to the neurohypophysis. When it is needed, it is released into the blood. ADH is bound to the distal renal tubules and collecting ducts, binds to the cell membrane receptor, activates adenylate cyclase, increases cAMP, activates protein kinase, and promotes membrane protein phosphorylation on the lumen. The membrane protein model is changed, and the pores of the cell membrane on the inner side of the lumen are enlarged, the number of pores is increased, the water permeability is enhanced, and the water absorption is promoted.

The role of ADH:

1. Regulate water metabolism: When the plasma osmotic pressure is increased, the release of ADH can be increased, and the far-curved tubules and collecting ducts can be absorbed to absorb water, thereby reducing the amount of urine; on the contrary, the release of ADH is reduced and the amount of urine is increased.

2. Contraction of peripheral and visceral arterioles: leading to increased blood pressure, decreased blood flow to the heart, decreased blood output, coronary artery involvement, myocardial ischemia.

Patients with central diabetes insipidus have partial or complete destruction of vasopressin secretion, resulting in a lack or severe deficiency of ADH secretion, while plasma ADH levels in patients with renal diabetes insipidus are normal or slightly elevated, but the kidney does not affect ADH. Sensitive and resistant, both of which lead to inability to concentrate urine, increased urine output, dehydration, loss of body water, plasma osmotic pressure, mild rise in plasma sodium, stimulation of thirst center caused by thirst and water intake To prevent further dehydration, therefore, in the case of free drinking water, no dehydration occurs in patients with central diabetes insipidus or renal diabetes insipidus unless the patient has damage to the thirst mechanism or other reasons are not enough to drink water. Compensate for the loss of water in the urine.

The primary polydipsia patient is different from the above two. It is due to the patient's habitual polydipsia, or due to mental illness, neurosis, or abnormal thirst mechanism, excessive intake of water, expansion of body fluids, and The plasma osmotic pressure and the blood sodium level are slightly reduced, so the release of ADH secretion is inhibited, causing the dilution of urine and the increase of urine output to prevent further increase of body water, so the patient's low plasma osmotic pressure and low blood sodium level are not It will be further aggravated, and after limiting water intake, it can relieve the inhibition of ADH secretion in patients with mental polydipsia.

Diabetes insipidus prevention in the elderly

The prevention of diabetes insipidus can be divided into 3 levels.

Primary prevention

To avoid the onset of diabetes insipidus, the causes of various types of diabetes insipidus are different. For the cause of the disease, some intervention measures are taken to avoid or reduce the onset of diabetes insipidus. For example, for mental illness, neurosis, strengthen Nursing, limit the amount of water per day, measure the amount of intake, can prevent the occurrence of diabetes insipidus, for hypokalemia, hypercalcemia, diabetes, pyelonephritis and other diseases, early effective treatment, can also be used as a prevention of renal diabetes insipidus An attempt has occurred. Some cases of renal diabetes insipidus are caused by drugs. Weighing the pros and cons, reducing the amount of drugs or stopping drugs, can also prevent the occurrence of diabetes insipidus, and actively control the infection of tuberculosis, syphilis, meningitis and so on. Disease, pay attention to self-safety, avoid the occurrence of head trauma, and reduce the chance of inducing diabetes insipidus.

2. Secondary prevention

Early detection of diabetes insipidus and active treatment, in the actual work, central diabetes insipidus is the most common, more than 90% of which are idiopathic, postoperative or traumatic and intracranial space-occupying lesions or invasive disease, so for Brain surgery, brain trauma, brain tumor patients, should be followed up regularly to early detection of diabetes insipidus, regular follow-up of family history of diabetes insipidus, early detection and treatment of polyuria, patients with multiple drinking, can achieve urine collapse Early detection and treatment of the disease.

3. Three levels of prevention

Prevention of serious complications, diabetes insipidus long-term polyuria, bladder expansion, ureter, hydronephrosis, some patients due to limited drinking water or lack of thirst, can occur dehydration, central nervous system damage, due to pituitary-hypothalamic In patients with diabetes mellitus with tumor or invasive disease, in addition to dehydration, there are still hypogland hypofunction, tumor compression symptoms, increased intracranial pressure, etc., high mortality, diabetes insipidus combined with anterior pituitary dysfunction, often Can cause infections, diarrhea, vomiting, loss of water, hunger, cold, heat stroke, surgery, trauma, anesthesia, alcoholism and taking sedative sleeping pills, hypoglycemic drugs to induce pituitary crisis, abnormal body temperature (high body temperature or hypothermia), low Blood sugar, circulatory failure, respiratory failure, water poisoning, etc., severe cases can also occur coma and convulsions, life-threatening, so early detection of diabetes insipidus and early anti-diuretic treatment, treatment of primary disease, treatment of various diseases, control of various Predisposing factors can reduce the occurrence of these complications, improve the quality of life, and prolong the life of patients.

4. Community intervention

In the community, strengthen the promotion and education of diabetes insipidus, strengthen the screening of diabetes insipidus, can find diabetes insipidus early, in community health care, through the understanding of the cause of diabetes insipidus, you can see the habitual polydipsia, brain Department of trauma and tumor or invasive diseases, surgery, infectious diseases, drugs affecting renal tubular function, electrolyte disorders, etc., can lead to the occurrence of diabetes insipidus, through detailed medical history, early detection of suspected diabetes insipidus patients, through the measurement of plasma Osmotic pressure, urine osmotic pressure, urine specific gravity, can basically diagnose diabetes insipidus, if necessary, guide it to the higher level hospital for further examination, can further determine the type of diabetes insipidus, the cause, reasonable drinking water guidance for patients, and then disable it Drugs that affect kidney function, correct electrolyte imbalance, can prevent the occurrence of diabetes insipidus, in addition, strengthen safety education, prevent the occurrence of head trauma, actively control infectious diseases such as tuberculosis, can also prevent the occurrence of diabetes insipidus, such as tumors Early detection, early treatment can also alleviate the symptoms of diabetes insipidus and prolong the life of patients. For patients with diabetes insipidus, guide , And promptly correct dehydration, prevent the occurrence of water intoxication, infection, can prevent serious complications and further to a higher level hospital to gain time and opportunity.

Elderly diabetes insipidus complications Complications hypothyroidism hyponatremia

Can be complicated by hypothyroidism, renal insufficiency, pyelectasis, hypokalemia, hyponatremia, water poisoning.

Symptoms of diabetes insipidus in the elderly Common symptoms Loss of polydipsia, polyuria, weakness, urine, urine, osmolality, diabetes, renal urinary disintegration, increased intracranial pressure, deafness

The main clinical manifestations are polyuria, polydipsia, and polydipsia. The common urine volume is 5-10L in 24h. In severe cases, the urine volume can reach 16~24L per day and night. It is also reported that it reaches 40L/d, and the urine is clear and colorless. Day and night urine volume is similar, regardless of day or night, every 30 to 60 minutes need to urinate and drink water, urine specific gravity is low, below 1.008, closer to 1.001, urine osmotic pressure is lower than plasma osmotic pressure (<300mmol / kg H2O), mild patients, Urine osmotic pressure can exceed plasma osmotic pressure, but even in the water-free test, urine can not be fully concentrated, the osmotic pressure is below 600mmol/kg H2O, due to the discharge of a large amount of hypotonic urine, low specific gravity urine, plasma osmotic pressure is slightly elevated Stimulating thirst, the amount of drinking water per day and night is equivalent to the amount of urine, and the amount is quite stable. The patient likes to eat half-flow food, like cold drink. If there is enough water supply, the patient's health is generally unaffected, and dehydration will not occur. Children who are fully drinking water or are forcibly restricted to water, especially those who cannot get active water, are prone to dehydration.

Examination of diabetes insipidus in the elderly

1. Determination of urine specific gravity: Take any urine to measure urine specific gravity, central and renal diabetes insipidus urine specific gravity <1.005.

2. Determination of plasma and urine osmotic pressure: central diabetes insipidus and renal diabetes insipidus, plasma osmotic pressure may be higher than normal, urine osmotic pressure is less than plasma osmotic pressure, partial urinary insipidus urine osmotic pressure may exceed plasma Osmotic pressure, but <600mmol / L, and mental polydipsia, its plasma osmotic pressure may be slightly lower.

3. Water vasopressin test

(1) Principle: After the water is banned, the urine volume of normal people and mental polydipsia decreases, the urine osmotic pressure and urine specific gravity increase, central diabetes insipidus is lack of AVP secretion, or renal diabetes insipidus does not respond to AVP. After the water is forbidden, a large amount of low osmotic pressure is still discharged, and low specific gravity urine, the body's plasma osmotic pressure and plasma sodium level increase due to dehydration. When the urine is concentrated to the maximum osmotic pressure and can no longer rise, the vasopressin is injected, and the normal person is forbidden. A large amount of AVP has been released from the body after water. After injection of exogenous AVP, urine osmotic pressure is no longer elevated, while AVP is absent in patients with central diabetes insipidus. After injection of exogenous AVP, urine osmotic pressure is further increased. Patients with diabetes insipidus still have no response after injection of vasopressin.

(2) Method: This experiment should be carried out under close observation. Before weighing the water, the body weight, blood pressure, urine volume and urine specific gravity, urine osmotic pressure, water-blocking time are 10~14h, and urination is performed once every 2 hours during the water-free period. Measure urine volume, urine specific gravity, urine osmotic pressure, hourly weight and blood pressure, when the urine osmotic pressure reaches the peak flat top, that is, the difference between two consecutive osmotic pressures <30mmol/L, blood is taken to measure plasma osmotic pressure, and then Subcutaneous injection of vasopressin 5U, urine osmotic pressure 1h after injection, compared with urine osmotic pressure before and after injection, such as patients with more urination, weight loss of 3% to 5%, or blood pressure decreased significantly, should immediately stop the test, let The patient has water.

(3) Results and analysis:

1 Normal people have a significant reduction in urine output after water ban, urine specific gravity exceeds 1.020, urine osmotic pressure exceeds 800mmol/L, and there is no obvious dehydration. After injection of vasopressin, urine osmotic pressure generally does not increase, only a few people increase slightly. But no more than 5%.

2 Mentally annoying people are close to or similar to normal people.

3 Central diabetes insipidus and renal diabetes insipidus patients still have more urine after water ban, urine specific gravity generally does not exceed 1.010, urine osmotic pressure does not exceed plasma osmotic pressure, partial urine insipidus can exceed the urine specific gravity after water ban 1.015, but less than 1.020, the urine osmotic pressure can exceed the plasma osmotic pressure, but <6mmol / L.

4 After injection of vasopressin, the urinary osmotic pressure of patients with central diabetes insipidus increased further, at least 9% more than before injection, the more severe the AVP deficiency, the greater the percentage increase.

5 patients with renal diabetes insipidus, after injection of vasopressin, still no response.

This method is simple and reliable, and is the most practical and convenient method for diagnosing diabetes insipidus.

4. Hypertonic saline test

(1) Principle: Rapid infusion of hypertonic saline to increase osmotic pressure and stimulate endogenous AVP secretion.

(2) Method:

1Carter-Robbins method: prepare 2.5% hypertonic saline with normal saline or water for injection, 10% NaCl, prepare 10U pituitrin, drink 20ml/kg body weight, drink well within 1h, start at 30min after drinking, every 15 1 minute to stay in the urine, 5 ml/min or more after 2 consecutive urine, 2.5% hypertonic saline 0.25ml / (min·kg) drip 45min, every 15 minutes after the start of the drip, 1 time, high permeability saline drip After 30 minutes, when there was no significant reduction in urine output, 5 U of pituitrin can be injected subcutaneously, and urine is given twice every 15 minutes after injection.

25% hypertonic saline test: 5% hypertonic saline was prepared by diluting 10% NaCl with normal saline or water for injection, and the method was the same as Carter-Robbins method, but 5% hypertonic saline 0.05 ml/(min·kg) was instilled for 2 hours. .

(3) Analysis of results: normal people and mentally irritated people, after infusion of hypertonic saline, urine output decreased, urine concentration, after injection of vasopressin, urine is no longer concentrated, central diabetes insipidus The reaction to hypertonic saline was defective. After the addition of vasopressin, the urine was concentrated. Renal diabetes insipidus did not respond to hypertonic saline and exogenous AVP.

Because hypertonic saline can expand blood volume, increase intracranial pressure and cardiac burden, it is now rarely used.

5. Nicotine test

(1) Principle: Nicotine directly promotes the secretion of AVP in the hypothalamus-pituitary lobes. This effect is sometimes strong, but individual differences are large.

(2) Method: Drink 20ml/kg body weight on an empty stomach in the morning, drink as much as possible within 20min, and leave urine every 15min after drinking water. If the urine volume is more than 5ml/min for 2 consecutive times, there will be 3 smokers and 2 non-smokers. Cigarettes were smoked within 30 minutes. After smoking, the urine was continuously administered 4 times. The urine volume, urine osmotic pressure, blood collection before and after smoking, plasma osmotic pressure, plasma AVP.

(3) Analysis of results: The urine volume of normal people decreased to less than 25% of the control after smoking, the urine osmotic pressure exceeded the plasma osmotic pressure, and the individual differences of the reaction were large. The plasma AVP concentration slightly exceeded 50 pg/ml, but some patients did not respond. In patients with complete diabetes insipidus, the urine volume is not significantly reduced, the urine osmotic pressure is lower than the plasma osmotic pressure, the urine osmolality of the mental polydipsia can exceed the plasma osmotic pressure, and the adrenal insufficiency is the same as the hypertonic saline test. The first 4 hours, after oral administration of 30 mg of hydrocortisone acetate, the test was carried out.

Nicotine can directly stimulate the release of AVP from neurons. In theory, it can distinguish between osmotic receptor damage or neuron damage, but it has no practical significance, and it has nausea, vomiting, dizziness, paleness, blood pressure drop, and decreased glomerular filtration rate. Such side effects are no longer needed.

6. Determination of vasopressin: The level of plasma can be measured by radioimmunoassay, which can be measured at any time or after ban. The plasma AVP (random drinking water) of normal people is 2.3-7.4 pmol/L, which can be significantly increased after water ban. In patients with central diabetes insipidus, plasma vasopressin levels did not increase when water was absent, while plasma vasopressin was significantly elevated in patients with mental polydipsia and renal diabetes insipidus (Table 1).

After the diagnosis of diabetes insipidus is determined, the cause must be as clear as possible. SARA X-ray, visual field examination, CT or MRI should be performed to confirm or exclude the presence or absence of pituitary or nearby tumors. The MRI of the pituitary-hypothalamic region Diagnosis has provided help, and it is possible to observe a space-occupying lesion as small as 3 to 4 mm. It is also possible to see thickening, tortuosity, interruption or sectional change of the pituitary stalk, and in the centralized diabetes insipidus on a T1-weighted image. The high signal of the normal existence of the pituitary gland disappears, and renal diabetes insipidus and primary polydipsia still exist during polydipsia. Although some normal healthy people may also have this sign, it is not difficult to distinguish with clinical symptoms and other examinations. MRI examination of the sellar region in patients with central diabetes insipidus is superior to CT scan in the observation of the presence or absence of microscopic lesions. When it is difficult to judge the nature of the small lesions in the sellar region and determine whether surgery or radiation therapy is needed, it must be strict. Follow-up observation, review MRI, some tumor lesions may increase rapidly within a few months, or the progress may be very slow, it is necessary to pay attention to the small body lesions found in the pituitary, not necessarily diabetes insipidus the reason.

Diagnosis and diagnosis of diabetes insipidus in the elderly

Differential diagnosis

Diabetes insipidus should be differentiated from polyuria caused by other common medical diseases.

1. Diabetes: This disease often has more food, weight loss, polydipsia, blood sugar, urine sugar positive, easy to identify, need to pay attention to individual cases of diabetes insipidus, diabetes.

2. Hypercalciuria: seen in parathyroidism, sarcoidosis, vitamin D poisoning, multiple myeloma, cancer bone metastasis, etc., with primary symptoms, to identify.

3. Hyperuricemia: seen in primary aldosteronism, congenital nephropathy, potassium loss nephropathy, renal tubular acidosis, Liddie syndrome, Bartter syndrome.

4. Hyperosmotic polyuria: urine specific gravity>1.020, urine osmotic pressure>300mOsm/kg, seen in: 1 urine sugar increased; 2 urea increased (high protein, high energy nutrition); 3 increased urine sodium (adrenal cortex) Decrease).

5. hypotonic polyuria: urine specific gravity <1.006, urine osmotic pressure <280mOsm / kg, seen in: 1 renal dysfunction; 2 potassium loss nephropathy; 3 renal diabetes collapse; 4 hypercalciuria; 5 central urine Insufficiency; 6 mental polydipsia.

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