Ms. HG is 20 yo, 5’8” (172.7 cm), and currently weighs 135 lbs(61.3 kg).  She is experiencing fever, increased thirst, and polyuria; in addition, she suspects a urinary tract infection and thus made an appointment to see her primary care physician. She reported no recent change in appetite but reported losing a few pounds over the past month with no particular effort. Following a medical history/physical exam, the physician ordered a comprehensive metabolic panel, complete blood count, and urine culture.  A subset of these lab tests are reported below.

Plasma osmolality 325 mOsm/L (normal: 300 mOsm/L)

Serum albumin 3.1 g/dl (normal 3.5 -5 mg/dL)

Plasma glucose 410 mg/dl (normal (70 – 100 mg/dL)

Serum sodium 127 mEq/L (135 – 145 mEq/L)

Serum potassium 3.2 mEq/L (normal (3.5 – 5 mEq/L)

Hemoglobin A1C 13%

1. Explain why this patient’s blood (serum) osmolality iselevated.

2. Explain why this patient is experiencing polyuria?

3. What does the level of hemoglobin A1C indicate?

4. What are possible reasons that the electrolytes are low?