Nephrogenic Diabetes Insipidus.

Nephrogenic Diabetes Insipidus

What is nephrogenic diabetes insipidus?

Nephrogenic diabetes insipidus (NDI) is a rare disease. It is either inherited or acquired. This happens when the kidneys cannot concentrate the urine. The body balances the urine excreted from the body with the fluid we eat. However, people with NDI produce excessive amounts of urine. This condition is called polyuria and causes excessive thirst or polydipsia.

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What is the difference between diabetes insipidus and diabetes mellitus?

Nephrogenic diabetes insipidus is different from conventional diabetes mellitus. In diabetes mellitus, the body either cannot produce or use insulin properly. On the other hand, kidney resistance against arginine vasopressin (AVP) is the cause and characteristic of NDI. Vasopressin (a type of antidiuretic hormone) maintains the body's water balance. An excessive amount of urine production (polyuria) and dehydration are associated with excessive thirst (polydipsia) from NDI.

What are the specific classifications and features of NDI?

Inherited NDI: It is inherited as an X-linked recessive disorder. This rare form of inheritance is found as an autosomal recessive or dominant disorder. Two different genes are blamed for genetic NDI.

Acquired NDI- This occurs when there is a blockage in the use of drugs (such as lithium therapy), kidney disease, and in the tube carrying urine from the kidneys to the bladder. It is also caused by a long-term lack of metabolic balance, such as low potassium (hypocalcemia) or high calcium (hypercalcemia) in the blood.

What are the signs and symptoms of diabetes insipidus?

The symptoms of NDI vary from person to person. Some, however, may be more severely affected than others. Obtained type but less severe than hereditary type. Hereditary NDI symptoms usually appear after birth and most babies are diagnosed within a year of birth. The NDI obtained is mostly in the case of adults and the symptoms appear very slow.

The main symptoms of NDI:

• Frequently excessive thirst (polydipsia)
• Excessive urine production (polyuria)
• Excessive urination at night (Nocturia)
• Symptoms may vary with age. Some common symptoms are weakness, hesitation, dry mucous membranes, dry skin, and weight loss due to repeated dehydration.
• Severe problems with excessive urination can lead to an abnormal amount of urine in the kidneys (hydronephrosis), bedwetting at night (nocturnal aneurysm), swelling of the urethra due to obstruction (distances), abnormally large bladder (megacystis). Some people have an extended urinary tract.
• Vomiting
• Frequent fever for unknown reasons
• Constipation
• Laziness
• Discomfort or annoyance

What causes nephrogenic diabetes insipidus?

Obtained or inherited nephrogenic diabetes insipidus impairs kidney response to vasopressin. In this condition, depending on the gene, the kidney responds partially or completely to vasopressin. It reduces the ability of the kidneys to concentrate urine and as a result, changes the water balance in various ways. There are many causes of secondary nephrogenic diabetes insipidus, which are:

• Kidney cyst
• Obstruction of the outlet tube coming out of the kidney
• Kidney infections
• High levels of calcium in the blood
• Rare conditions include Sjogren's syndrome, amyloidosis, and Bardet-Baidel syndrome.
• Some cancers
• Low levels of potassium in the blood cause chronic hypocalcemic nephropathy, kidney disease.
• Cardiopulmonary bypass, which affects vasopressin levels and may require treatment with desmopressin

How is nephrogenic diabetes insipidus diagnosed?

To avoid life-threatening complications, NDI needs to be diagnosed early. This test shows whether the kidneys can retain the right amount of water in the body to maintain the concentration and mass of urine. NDI symptoms are diagnosed in childhood problems. Doctors usually do urine and blood tests to diagnose the disease.

Test:

• Polyurea test (24-hour urine output)
• The first urine test of the day checks for specific gravity or density and even chemicals.
• Measurement tests are performed to measure the concentration and pH of the urine. It even measures the levels of sodium, potassium, chloride, and creatinine 
• Other NDI tests include:
• MRI to measure kidney size and anatomical abnormalities
• Blood tests to measure the amount of potassium, sodium, chloride, creatinine, and urea in the blood
• Renal sonography to look for renal disorders and long-term damage
• The doctor also recommends a water dehydration test

How is nephrogenic diabetic insipidus treated?

First-line treatment:

Dietary changes: Often the first line of treatment is dietary changes. In general, doctors recommend low-protein for adults, sodium-rich foods. This change reduces the amount of urine excreted.

Second-line treatment:

• Medicine
• The synthetic type of ADH
• Thiazide diuretics
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Intravenous hydration