A 39-year-old previously healthy woman found to have the following Chem-6 lab results in a routine check-up: Na 121; K 4.3; Cl 103; Glucose 223; Urea 8; Creatinine 0.8. Her physical exam is normal apart from the fundoscopic finding below.
1- Which of the following is the most appropriate next step?
- a- Order blood gases (ABG)
- b- Order serum and urine ketones
- c- Order serum osmolality
- d- a and b
- e- All of the above
2- Which of the following is most likely in this patient?
- a- Abnormal thyroid function tests
- b- Urine osmolality < 100
- c- Dyslipidemia
- d- a and c
- e- All of the above
3- What is the most appropriate treatment for her hyponatremia?
- a- Control her diabetes mellitus
- b- Restrict free water intake
- c- Infuse intravenous saline
- d- Thyroxine
- e- None of the above
The resolution of the case:
A case of pseudohyponatremia due to hyperlipidemia.
Serum osmolality establishes the diagnosis as it it normal in the setting of hyponatremia (isotonic hyponatremia).
The fundi show the characteristic l Lipemia Retinalis appearance
The serum sodium should not be treated in this condition as it is a false result (in vitro).