Electrocardiogram after 2 weeks of diarrhea.

A 41-year-old man, known to be HIV positive for at least 3 years (CD4 count on this admission, 134/mm3; reference, 228–2290), presented with a 2-week history of sore throat, dysphagia, odynophagia, change in his voice, fatigue, and exertional dyspnea. Only later did he admit to having 4 to 6 large watery stools per day for the same length of time. An electrocardiogram (ECG) recorded on admission showed sinus rhythm, sagging ST segments, and giant U waves, with the T waves appearing as slight protuberances on the upslopes of the U waves near their apices (Figure). The repolarization pattern is typical of severe hypokalemia, and a serum potassium level obtained at the time of the ECG was 1.2 mmol/L (reference, 3.6–5.2). Diarrhea, the major cause of the hypokalemia, was due primarily to Clostridium difficile colitis, and the patient’s stool also was positive for Cryptosporidium antigen. Dysphagia and odynophagia, due to thrush and mediastinal and cervical emphysema, led to decreased oral intake that also played a role in causing both hypokalemia and the dehydration that was manifested by admission hypotension (blood pressure, 91/57 mm Hg), hemoconcentration (hemoglobin, 17.9 g/dL; hematocrit, 49%), and kidney failure (serum creatinine, 2.8 mg/dL; blood urea nitrogen, 66 mg/dL). With potassium and fluid replacement and appropriate antimicrobial therapy, the