Case Study

Describe the mechanism by which normal fluid regulation in the body occurs.

-The kidneys act to regulate the volume of water in the plasma by producing less urine to conserve water when the body is approaching dehydration, and by removing extra water from the plasma when the body is in a state of over-hydration. This extra water is stored prior to excretion in the bladder as urine. The rate of fluid intake is controlled by the thirst mechanism, and the rate of fluid excretion is controlled by antidiuretic hormone.

What is considered to be excessive thirst and urination in an adult?

An adult who urinates more than 50mL/kg body weight per 2 hours and an adult who drinks more than 1 gallon or about 12 glasses of beverages per day.

List and briefly describe the four types of diabetes insipidus.


Neurogenic DI- is caused by a deficiency of antidiuretic hormone

Nephrogenic DI- is caused by insensitivity of the kidneys to effect the antidiuretic hormone

Dispogenic DI- is caused by being really thirty and drinking way too much liquid of any kind.



Gestagenic DI- is only during pregnancy and it is causd by a deficiency of the antidiuretic 

How is pituitary diabetes insipidus diagnosed?

It is diagnosed with a urinalysis, a urine deprivation test and an MRI.

5. In what ways is diabetes insipidus similar to diabetes mellitus? In what ways do they differ?

Diabetes mellitus differs because it results from the body not being able to produce insulin. They are similar because they have some of the same symptoms, for example excessive thirst and urination.

6. How does the mechanism by which diuresis occurs with diabetes insipidus differ from that which occurs in diabetes mellitus?

7. How does diabetes insipidus compare with a condition called syndrome of inappropriate anti- diuretic hormone (siadh)?

8. What other conditions result in polyuria and polydipsia (pu/pd)?

9. What is ddavp and how is it administered?

10. Why should a person who has...