A 54-year-old man is brought to the emergency department by emergency medical services after his wife found him unresponsive in their garage. She reports that he has a history of major depressive disorder and alcohol use disorder. An open, half-empty bottle of engine antifreeze was found nearby. Vital signs show a temperature of (), pulse of /min, blood pressure of mm Hg, and respirations of /min. Physical examination reveals a comatose patient with no focal neurological deficits.
Laboratory studies reveal the following:
| Parameter | Value |
|---|---|
| Sodium | mEq/L |
| Potassium | mEq/L |
| Chloride | mEq/L |
| Bicarbonate | mEq/L |
| Blood urea nitrogen | mg/dL |
| Creatinine | mg/dL |
| Glucose | mg/dL |
| Ethanol | Undetectable |
| Measured serum osmolality | mOsm/kg |
Arterial blood gas on room air:
pH:
: mm Hg
: mm Hg
Urinalysis reveals the presence of envelope-shaped crystals.
Based on the provided laboratory values, what is the patient's serum osmolar gap in mOsm/kg ?
Cevap: 36 mOsm/kg
Cevap
36
The patient's osmolar gap is mOsm/kg . This is obtained by first finding the calculated serum osmolality using the formula: . Substituting the provided values yields mOsm/kg . Subtracting this calculated value from the measured osmolality ( mOsm/kg ) gives a gap of mOsm/kg .
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Anahtar Kavram
The serum osmolar gap is calculated by subtracting the calculated serum osmolality () from the measured serum osmolality. A gap mOsm/kg suggests the presence of unmeasured osmotically active agents such as toxic alcohols (e.g., ethylene glycol, methanol).