Will NDI ever go away?

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Topic: NDI: An Overview
Author: Bichet, Daniel G.
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Nephrogenic diabetes insipidus (NDI) can either be acquired or inherited. If a person has inherited NDI, that means one of two genes, either his vasopressin-2 gene or his aquaporin-2 gene, is mutated and as a result his kidneys cannot reabsorb the body water flowing through his kidney collecting ducts. This type of NDI will not go away because the mutated gene responsible for disrupting the water reabsorption process will not go away. Most acquired forms of NDI, however, can be healed.

Researchers have learned a great deal about the molecular sequence underlying the water reabsorption process and a great deal about the nature of the mutations that result in NDI. Their knowledge gives them ground to speculate that the means for reversing NDI - making it go away - might be discovered one day in the next decade. The cure may come through genetic therapy, manipulating the mutated gene responsible for inherited NDI so that the protein it encodes and helps create will be able to function properly. Or the cure may come through a more complete knowledge of the molecular sequence involved in the water reabsorption process and the cellular mechanics supporting it. Some researchers suggest there may be other molecular sequences involved in the water reabsorption process. If this proves true, then one day researchers might be able to discover how the alternative molecular sequence can more fully take over for the disrupted molecular process that results in NDI. But for now, inherited NDI can only be managed, not cured.

Sometimes NDI occurs as a result of a more basic, underlying systemic disorder such as sickle cell anemia. If the systemic disorder or disease cannot be reversed, then the resulting NDI cannot be expected to stop.

Acquired NDI, however, can go away. Lithium-induced NDI, the most common form of acquired NDI, can slowly reverse itself once lithium is discontinued. This may take many weeks or months, and in some cases, does not go away at all. But in most cases, the NDI does stop. The benefits of lithium to control certain psychiatric diseases might be superior to the symptoms and signs of lithium-induced nephrogenic diabetes insipidus.

Sometimes the NDI-inducing underlying systemic disorder may be an electrolyte disturbance such as abnormally high levels of plasma calcium (hypercalcemia) or abnormally low levels of plasma potassium (hypokalemia). These disorders are sometimes more easily correctable. And as they are corrected, the NDI is reversed.

NDI that occurs after unilateral or bilateral ureteral obstructions have been reversed will also go away on its own after several weeks. Occasionally, NDI occurs during pregnancy. This too, is transient and will reverse itself after the pregnancy. NDI caused by dietary abnormalities is reversible once the diet becomes balanced again.