A 41-year-old man is evaluated in the emergency department for a 2-day history of profound, generalized muscle weakness that has progressed to the point where he cannot stand unassisted. He reports no recent illnesses, trauma, diarrhea, or vomiting. His medical history is notable for recurrent calcium phosphate kidney stones over the past three years. He takes no prescription medications but occasionally uses ibuprofen for back pain. He works as a software engineer but spends his weekends restoring antique wooden boats in an enclosed, poorly ventilated workshop. His social history includes drinking 1-2 glasses of wine on weekends; he denies illicit drug use but admits to frequently using industrial degreasers and paint thinners without a respirator. Vital signs are within normal limits. Physical examination reveals symmetric 2/5 muscle strength in the proximal and distal lower extremities, with diminished deep tendon reflexes.
Laboratory studies reveal:
| Laboratory Parameter | Value | Reference Range |
|---|---|---|
| Sodium | 138 mEq/L | 136-145 mEq/L |
| Potassium | 2.1 mEq/L | 3.5-5.0 mEq/L |
| Chloride | 116 mEq/L | 95-105 mEq/L |
| Bicarbonate | 12 mEq/L | 22-28 mEq/L |
| Blood urea nitrogen | 14 mg/dL | 7-18 mg/dL |
| Creatinine | 0.9 mg/dL | 0.6-1.2 mg/dL |
| Urine pH | 6.8 | 4.5-8.0 |
| Urine sodium | 40 mEq/L | variable |
| Urine potassium | 15 mEq/L | variable |
| Urine chloride | 30 mEq/L | variable |
Which of the following elements from the patient's history is the most likely primary etiology of his presentation?
- Inhalation of volatile hydrocarbon solventsAnswer
- BOccult systemic absorption of heavy metals
- CIntermittent ingestion of nonsteroidal anti-inflammatory drugs
- DUnreported excessive consumption of ethanol
- EUnderlying metabolic derangements from recurrent nephrolithiasis