An elderly client admitted with new-onset confusion, headache, and bounding pulse has been drinking copious amounts of water and voiding frequently. The nurse reviews the lab results (see chart)....

An elderly client admitted with new-onset confusion, headache, and bounding pulse has been drinking copious amounts of water and voiding frequently. The nurse reviews the lab results (see chart). Which of the abnormal lab values is consistent with the client's symptoms?

1. Serum osmolality.

2. Platelet count.

3. Serum sodium.

4. Urine specific gravity.