An 18-year-old man is brought to the emergency department because of acute onset of weakness and confusion. The accompanying family member found him on the floor at home mumbling incoherently and called 911. The patient is in good health, takes no medications, and has no previous history of a similar occurrence.
His temperature is 36.7 C (98 F), blood pressure is 110/70 mm Hg, pulse is 90/min, and oxygen saturation is 97% on room air. The patient is oriented only to person. His lungs are clear to auscultation. His abdomen is soft and non-tender. Cranial nerves are intact. There is flaccid weakness of all four extremities and absent deep tendon reflexes.
Laboratory results are as follows:

Which of the following is the most likely cause of this patient's condition?

Question

An 18-year-old man is brought to the emergency department because of acute onset of weakness and confusion.  The accompanying family member found him on the floor at home mumbling incoherently and called 911.  The patient is in good health, takes no medications, and has no previous history of a similar occurrence.
His temperature is 36.7 C (98 F), blood pressure is 110/70 mm Hg, pulse is 90/min, and oxygen saturation is 97% on room air.  The patient is oriented only to person.  His lungs are clear to auscultation.  His abdomen is soft and non-tender.  Cranial nerves are intact.  There is flaccid weakness of all four extremities and absent deep tendon reflexes.
Laboratory results are as follows:

Which of the following is the most likely cause of this patient's condition?

Quizplus · Accepted Answer

11ec193a_96a9_a3b5_853d_5d1bbe4f115f_MD0002_00 This patient's presentation of non-anion gap metabolic acidosis, marked hypokalemia, hypophosphatemia, and inappropriately high urine pH is consistent with distal renal tubular acidosis (RTA). The urinary anion gap (Na + K - Cl) is also positive, suggesting a renal acidification defect from decreased renal ammonium production. Distal RTA in adults is usually due to autoimmune diseases (e.g., Sjögren's, rheumatoid arthritis), drugs (e.g., amphotericin), or toxin ingestion (e.g., toluene). Toluene solvent inhalation can cause renal tubular acidosis with cognitive impairment. Toluene is inhaled and then converted by the liver to hippuric acid, which can cause an elevated anion gap metabolic acidosis in the early stages. However, hippuric acid is rapidly excreted by the kidneys along with sodium and potassium. There is also limited renal ammonium production and eventual distal RTA. The resultant serum hypokalemia leads to diffuse weakness, low level of rhabdomyolysis, and hypophosphatemia. Treatment is largely supportive with fluid and electrolyte repletion. (Choice A) Amphetamine abuse usually presents with increased alertness, euphoria, hypertension, tachycardia, hyperthermia, and hyponatremia (due to increased ADH release and water consumption). It is usually not associated with significant hypokalemia as seen in this patient. (Choice B) Guillain-Barré syndrome can produce flaccid quadriparesis, but it is not associated with the hypokalemia and non-anion gap metabolic acidosis seen in this patient. (Choice C) Severe diarrhea can produce a non-anion gap metabolic acidosis, hypokalemia, and hypophosphatemia. However, it is less likely to cause cognitive impairment in an otherwise healthy young individual. In addition, diarrhea usually causes a negative urinary anion gap instead of the positive urinary anion gap seen in this patient. (Choice E) Todd's palsy usually presents with focal weakness (e.g., hand, arm, or leg) after a seizure. Although the weakness may sometimes progress to paralysis, this patient's diffuse weakness and absent reflexes makes this unlikely. Educational objective: Sniffing toluene-containing solvents can result in renal tubular acidosis with marked hypokalemia and hypophosphatemia. The resultant electrolyte disturbances can produce life-threatening weakness. __________ References: Glue-sniffing and distal renal tubular acidosis: sticking to the facts. (http://www.ncbi.nlm.nih.gov/pubmed/1912400) Syndromes of toluene sniffing in adults. (http://www.ncbi.nlm.nih.gov/pubmed/7235417)

An 18-Year-Old Man Is Brought to the Emergency Department Because