A 28 year old male complained of excessive thirst and anincrease in urinary volume. Lab results showed the following
urine specific gravity (relative density) was less than 1.005(normal: 1.040 - 1.050)
urine osmolarity (concentration) was less than 200 mOsm/L(normal: 500 - 800 mOsm/L)
urinary volume was 15 L/day (normal: 1.5 to 3.0 L)
serum sodium was 145 mEq/L (normal: 136 - 145 mEq/L)
serum potassium was 2.8 mEq/L (normal: 3.6-5.1 mEq/L)
Water deprivation and hypertonic saline infusion did not causea significant reduction in urinary volume or urinaryosmolarity:
a urine specific gravity (relative density) of 1.009
a urine osmolarity (concentration) of 225 mOsm/L
However, there was a significant increase in the concentrationof the urine and decrease in urinary output followingadministration of ADH.
1)What condition is the patient suffering from
2)Why did the water deprivation and hypertonic saline infusionnot result in a concentrated urine?
3)Describe the location of the disorder in this individual. Isthe defect related to the lack of receptors or the lack of hormone;explain your answer?
4)How might the patient be treated for his condition, explainyour answer
5)Draw out the negative feedback pathway for the hormoneinvolved
