Mr. W. is а 50-yeаr-оld client with а histоry оf congestive heart failure who is being seen in the clinic today due to a weight gain of 4 lbs over the last 24 hours. Upon assessment, 2+ pitting edema is noted in both ankles. His blood pressure is currently 158/90. What is the underlying pathophysiology for decreased urine specific gravity in clients with fluid volume excess?