Diabetes insipidus: diagnosis and medical treatment

2021-07-26 12:52 AM

Diabetic insipidus without thirst is rare, caused by dysfunction of the hypothalamic-pituitary thirst center or in patients with loss of consciousness such as surgical anesthesia, traumatic brain injury.

Diabetes insipidus is a group of disorders of water balance characterized by the urinary frequency of more than 3 liters per day due to decreased ability of the kidneys to reabsorb water, which is caused by deficiency of secretion or resistance to antidiuretic hormone ADH) of the posterior pituitary gland.

The disease usually begins at a young age and is more common in men than in women. The etiology of diabetes insipidus is very complex, often divided into two types: central diabetes insipidus and peripheral diabetes insipidus.

Definite diagnosis

Clinical symptoms

Depending on the cause, the onset of the disease is sudden or gradual.

Frequent urination: > 3 days, up to 40 days, nocturia, clear urine.

Thirst, drink a lot: patients always feel thirsty, drink a lot of water, especially cold water. When water intake is not enough for water loss, the patient will develop dehydration.

Severe dehydration can cause hypernatremia and increased blood osmolality, collapse, and death.

Diabetic insipidus without thirst is rare, caused by dysfunction of the hypothalamic-pituitary thirst center or in patients with loss of consciousness such as surgical anesthesia, traumatic brain injury.

Symptoms of the causative agent, as in hypothalamic-pituitary tumors, manifest with hypersecretion or failure of the glands. When both ACTH and ADH deficiency is combined, the symptoms of diabetes insipidus may be masked (because glucocorticoids help the kidneys to excrete free water).

Subclinical symptoms

Normal or elevated blood sodium.

Urine density is less than 1.006.

Normal or high blood osmolality (290 - 300mosmol/kg).

Urinary osmolality is disproportionately low (<300mosmol/kg).

Blood osmolality and osmolarity must be measured at the same time.

The water restriction test did not respond.

Differential diagnosis

Need to distinguish

Diabetes: because the patient also has symptoms of frequent urination, thirst, drinking a lot. Lead requires a blood glucose test to be easily differentiated. In diabetes, urine density and urinary osmolality are normal or elevated.

Potomanie: Because the patient has a habit of drinking a lot of water, causing a lot of urine. Tests also showed low urine density and low urinary osmolality. The differential diagnosis is based on a well-responsive water restriction test.

Use an osmotic diuretic such as mannitol.

Tests for differential diagnosis

Water restriction test (fasting test):

This is a highly reliable method, conducted in a hospital at a specialized facility, and is indicated on patients with normal blood osmolality and blood sodium tests, and low urinary osmolality. This test is used for the purpose of distinguishing true diabetes insipidus from binge drinking.

The vasopressin or desmopressin test:

The purpose of the test is to help differentiate central diabetes insipidus from nephrogenic diabetes insipidus.

How to conduct the water restriction test and the vasopressin (or desmopressin) test

Prepare the patient:

Before the test, drink water freely during the night if urinating more than 2 times/night.

From midnight, do not drink if urinating 1 time/night.

Do not drink alcohol, tea, or coffee. Do not smoke for 12 hours before the test.

The patient had the following tests: urine density, osmolarity pressure, blood electrolytes, a blood protein.

Perform:

Fasting lasts 8-10 hours, starting at 5 am.

Check pulse, BP, weight every hour.

Measure urine output, urine osmolality, urine density every 1 hour. When urinary osmolality increases not more than 30 mmol/kg, then:

Take blood to test electrolytes, blood osmotic pressure, blood ADH quantification.

Minirin 2μg intramuscular injection or Minirin 30μg nasal spray.

Continue to monitor pulse, blood pressure, weight, urine volume, density, urinary osmolality every 1 hour within 2 hours after injection.

Stop testing when:

Weight loss > 5%.

Manifestations of severe dehydration.

When urine output is <30ml/hour and urine density is>1.015.

Evaluate test results.

Table of  Evaluate test results

Tests

Central diabetes insipidus

nephrogenic diabetes insipidus

Drunk mania

Blood sodium / ALT* any blood

Normal**/ increase

Normal/ increase

Decrease/normal

Any urinary ALTT

Low

Low

Low

Urinary ALTT after stopping the water restriction test

no change / little increase

No change or increase<9%

No change/increase<9%

Urinary ALTT after vasopressin injection or desmopressin spray

Increase>50%

No change <50%

No change/ tang<9%

ADH

low

Normal/ increase

Low

*ALTT: penetrating pressure; ** BT: normal.

Hypertonic sodium infusion test: combined with quantitative determination of blood osmolality, urinary osmolality, ADH is significant in distinguishing partial central diabetes insipidus from oral tics.

Quantification of ADH:

When the results of the water restriction test are clinically uncertain, ADH should be measured at the start of the test and before the administration of ADH.

Diagnose the cause

Central diabetes insipidus

Damage to the hypothalamus causes deficiency of the antidiuretic hormone ADH.

Definitive diagnosis is based on vasopressin test with good response.

Low ADH quantification.

When the diagnosis of central diabetes insipidus is confirmed, magnetic resonance imaging (MRI) of the hypothalamus is required to look for lesions (tumors...). In addition, due to surgical causes, hypothalamic radiation ...

Renal (peripheral) diabetes insipidus

Due to deficiency of ADH receptors in renal tubular cells or due to decreased sensitivity of receptors to ADH in cases of hypercalcemia or hypokalemia.

Serum calcium levels may be increased.

Serum potassium levels may decrease.

Renal ultrasound looks for lesions in the renal parenchyma - calyx of the kidney.

Treatment

Central diabetes insipidus

If there is a cause that requires combined treatment, for example, a hypothalamic-pituitary tumor, surgery may be required.

Rehydration: drink filtered water, hypotonic fluids if dehydration is a lot.

Vasopressin: 10 - 20 UI daily, 3 - 6 hours of action, can be injected subcutaneously from 5 -1 0UI/time, inject 3 -4 times/day, the drug is usually applied to cases Severe cases or cases of diabetes insipidus with other diseases such as coma due to traumatic brain injury, surgery.

Desmopressin (Minirin): easy to use, duration of action from 12-24 hours, causes vasoconstriction.

Nasal spray: 10μg desmopressin spray each time, 1-4 times/day depending on clinical response.

Subcutaneous injection form: 1μg - 2μg injected 1-2 times/day.

Oral form Minirin 0.1 mg or 0.2 mg oral dose: 0.05mg - 1.2mg/day.

Note: start at a low dose and increase gradually according to clinical response. Use the lowest dose that the patient has no symptoms of, need to monitor the amount of urine, blood sodium, to avoid water poisoning.

Nephrogenic diabetes insipidus

Renal diabetes insipidus so far has no specific treatment, commonly used drugs are thiazide preparations and salt-reducing diuretics, these drugs have the effect of reducing glomerular filtration rate and increasing reabsorption. water collection in the renal tubules.

Hydrochlorothiazide: 25mg tablets, 1-2 tablets per day.

It is possible to combine indomethacin + hydrochlorothiazide.

Prognosis

Depends on the cause of diabetes insipidus.

Central diabetes insipidus occurs after anterior pituitary surgery or craniocerebral surgery, the disease may resolve on its own after a few weeks. The disease may appear permanent with resection of the pituitary tail or necrosis of the pituitary tail.

Diabetes insipidus due to Ca++ and K+ disorders, after correcting for electrolyte disturbances, diabetes insipidus will be gone.