You interview Professor Purple and collect blood and urine specimens to be sent off to the lab for analysis. The lab reports that the urine osmolality 150 mOsm/kg, which means that the urine is overly dilute (too much water in the urine). The blood osmolality is 300 mOsm/kg, meaning that the blood is overly concentrated (too little water in the blood). The lab also reports that his blood glucose is completely normal. What is the significance of these clues?

1) Retaining too much water
2) Not retaining water
3) retaining too much fat
4) retaining too much fat