Tests Used to Diagnose Diabetes Insipidus

Some of the tests that are commonly used to determine the type of DI and/or look for its cause are:

In all cases, these tests should be performed only by a physician knowledgeable about their risks and interpretation. 

Once the type of DI has been established, the appropriate treatment can be selected. In the case of pituitary (central/neurogenic) DI, the treatment of choice is usually a synthetic form of antidiuretic hormone known as DDAVP. It can be taken by injection, by nasal spray or by tablet at whatever dose and/or frequency is necessary to completely eliminate the increase in urination, thirst and drinking without allowing periodic 'breakthrough" or 'escape'. The only 'toxic' side affect is water intoxication and it is rare provided the patient remembers to drink fluids only when he or she is truly thirsty.  Occassionally, other forms of treatment such as chlorpropamide may be used in preference to DDAVP.

Patients with dipsogenic DI or other forms of primary polydipsia cannot take DDAVP in the usual way because they invariably develop water intoxication during treatment. In this situation, the only thing that can be done is to voluntarily limit fluid intake as much as possible and, sometimes, to take a single small dose of DDAVP at bedtime to reduce the frequency of awakenings to urinate.

In patients with nephrogenic DI, treatment with DDAVP or chlorpropamide is ineffective. If the underlying cause of the DI cannot be eliminated, the signs and symptoms of DI usually can be reduced by decreasing the amount of salt in the diet and taking certain diuretics which have a paradoxical antidiuretic effect in this disease.

As in the case of the diagnostic tests, treatments should be undertaken only under the supervision of a physician knowledgeable about their use and potential side effects.