Identify the clinical features and treatment of diabetes insipidus (DI).

Explanation:

DI is the lack of ADH from hypothalamus (central DI)  or lack of its effect on the kidney receptors (nephrogenic DI).

It presents as polyuria, polydipsia, thirst and dehydration. Patient’s serum sodium is typically high unless patient has been drinking huge amounts of water to compensate for the water losses.  Patient's urine is dilute (SG around 1.005) because ADH effect is missing (normally ADH helps the kidney to re-absorb free water by increasing inward permeability to water and not for electrolytes in the collecting ducts).

It can be treated by using Intranasal DDAVP.

Some other therapies that are useful are thiazide diuretics (paradoxically decrease the urine output - by reducing the water delivery to the distal nephron). Lithium induced DI can also be treated with Amiloride (Drug of choice) or by Indomethacin.