A 49-year-old alcoholic man is admitted for diarrhea and generalized abdominal pain. His blood pressure is 134/80 mm Hg, pulse is 90/min, respirations are 16/min, and oxygen saturation is 97% on room air. He is disheveled and looks chronically ill. He is oriented to person and place. His mucous membranes are dry. His abdomen is soft and mildly tender in the epigastric region. He has no focal neurologic findings.
An electrocardiogram and chest x-ray is unremarkable. Stool samples are sent for culture and microscopic examination.
Laboratory results are as follows:

He is given thiamine and a multivitamin intravenously along with three liters of normal saline with 5% dextrose. He also receives intravenous potassium and magnesium supplementation. Thirty-six hours after admission, he complains of severe weakness. His oxygenation has decreased and he appears agitated.
Repeat laboratory results are as follows:

Which of the following is the most likely cause of this patient's new-onset weakness?

Question

A 49-year-old alcoholic man is admitted for diarrhea and generalized abdominal pain.  His blood pressure is 134/80 mm Hg, pulse is 90/min, respirations are 16/min, and oxygen saturation is 97% on room air.  He is disheveled and looks chronically ill.  He is oriented to person and place.  His mucous membranes are dry.  His abdomen is soft and mildly tender in the epigastric region.  He has no focal neurologic findings.
An electrocardiogram and chest x-ray is unremarkable.  Stool samples are sent for culture and microscopic examination.
Laboratory results are as follows:

He is given thiamine and a multivitamin intravenously along with three liters of normal saline with 5% dextrose.  He also receives intravenous potassium and magnesium supplementation.  Thirty-six hours after admission, he complains of severe weakness.  His oxygenation has decreased and he appears agitated.
Repeat laboratory results are as follows:

Which of the following is the most likely cause of this patient's new-onset weakness?

Quizplus · Accepted Answer

11ec193a_98fd_3093_853d_257c841881d8_MD0002_00 This chronically malnourished patient likely developed severe hypophosphatemia due to intravenous dextrose. Chronic alcoholics often have hypophosphatemia due to malnutrition, vitamin D deficiency, and diarrhea. When these patients are hospitalized, refeeding or hydration with glucose-containing fluids stimulates insulin release and drives phosphorus into cells. The phosphorus can drop to severe levels (< 1.0 mg/dL) 12-36 hours later, which further depletes ATP and causes symptoms (e.g., decreased diaphragmatic strength, cardiac function, and neurologic function). Alcohol can also cause decreased renal phosphate absorption in the proximal tubules and further worsen hypophosphatemia. Patients with phosphorus < 2.0 mg/dL may be treated with oral phosphates, while levels < 1.0 mg/dL require intravenous phosphate. However, dextrose-containing fluids should not be given to patients with hypophosphatemia at presentation (such as this patient) unless there is a clear indication for these fluids (e.g., hypoglycemia). (Choice A) Alcohol withdrawal may present with agitation, but usually presents with tachycardia, hypertension, and eventual delirium. In addition, this patient's generalized weakness makes alcohol withdrawal less likely. (Choice B) Hypomagnesemia is usually associated with hypokalemia, which is consistent with this patient's initial laboratory findings. Since magnesium repletion restores potassium to normal levels, this patient's repeat normal potassium level makes hypomagnesemia unlikely. (Choice D) Rhabdomyolysis can occur in alcoholics with severe hypophosphatemia who receive hyperalimentation without phosphate repletion, usually within the first 72 hours. However, these patients tend to have more biochemical abnormalities (e.g., elevated CK) and are usually not this symptomatic. (Choice E) Wernicke's encephalopathy typically presents with acute encephalopathy, oculomotor defects, and gait ataxia. This patient's normal neurological examination makes this less likely. Educational objective: Refeeding or giving dextrose-containing fluids to nutritionally depleted individuals (e.g., alcoholics) can lead to severe hypophosphatemia and resultant multi-organ dysfunction. __________ References: Refeeding syndrome and hypophosphatemia. (http://www.ncbi.nlm.nih.gov/pubmed/15888903) Severe hypophosphatemia: pathophysiologic implications, clinical presentation and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/10670405) Renal tubular dysfunction in chronic alcoholism-effects of abstinence. (http://www.ncbi.nlm.nih.gov/pubmed/8247056)

A 49-Year-Old Alcoholic Man Is Admitted for Diarrhea and Generalized