Complete heart block during potassium therapy in thyrotoxic periodic paralysis.

BACKGROUND: Although cardiac dysrhythmia is common in patients with thyrotoxic periodic paralysis (TPP), high-degree atrioventricular (AV) block complicated by cardiogenic shock, even under KCl supplementation, is rarely described. OBJECTIVES: To present a case of TPP in a patient who developed complete AV block with severe consequences due to paradoxical hypokalemia during KCl therapy. In addition, the management of acute hypokalemia in TPP is reviewed. CASE REPORT: A 41-year-old Chinese man with TPP presented to the Emergency Department with a 2-day history of paralysis in the extremities. He developed complete AV block with cardiogenic shock and respiratory failure, necessitating ventilatory support when plasma K(+) level decreased from 1.7 mmol/L to 1.3 mmol/L during KCl replacement of 30 mmol in 2 h. The administration of another 60 mmol KCl over 3 h achieved a plasma K(+) level of 2.1 mmol/L, resulting in the resolution of AV block and successful weaning. However, rebound hyperkalemia (K(+) 5.6 mmol/L) upon recovery was evident and uneventfully corrected. CONCLUSION: A paradoxical fall in serum K(+) concentration with potentially life-threatening complication is still underappreciated in patients with TPP on KCl supplementation. Early recognition and prompt therapy prevent untoward consequences.

Fasting plasma lactate concentrations in ambulatory elderly patients with type 2 diabetes receiving metformin therapy: a retrospective cross-sectional study.

BACKGROUND: Metformin is a worldwide accepted biguanide antidiabetic agent, and its effectiveness and benefit have already been well established. Among the side effects of metformin, lactate acidosis is the most problematic because of a high mortality rate, which impedes its use in clinical practice, especially in elderly patients with type 2 diabetes. Aging is associated with a decreased renal function and increasing comorbidities, but few data are available regarding plasma lactate levels in this unique population. In this study, we assessed fasting plasma lactate levels in ambulatory, elderly Taiwanese patients with type 2 diabetes, who were taking the drug, metformin, to identify independent risk factors for hyperlactemia in this group. METHODS: Sixty-six ambulatory type 2 diabetic patients, > 80 years of age (mean, 83.6 years; range, 80-90 years), receiving metformin therapy, were enrolled, from January 2005 to September 2009, in the Diabetes Case Management Program. A further 79 younger patients (also type 2 diabetics on metformin) served as controls (mean age, 59.9 years; range, 37-79 years). Fasting serum electrolytes, creatinine, bicarbonate, glycated hemoglobin, plasma glucose and lactate levels were determined. RESULTS: Lactate levels did not differ between the elderly and control groups (13.2 +/- 5.2 mg/dL and 13.5 +/- 4.8 mg/dL, respectively). None of the patients fulfilled the lactic acidosis criteria. Patients in the elderly group had a significantly lower daily metformin dose, higher creatinine levels, and lower estimated creatinine clearance, compared with the control group (all p < 0.05). Estimated creatinine clearance was negatively associated with lactate levels in the elderly group (p < 0.05, r = -0.27), but not in the control group. Patients with fasting plasma glucose levels > 130 mg/dL had a 2.8-fold increased risk of developing hyperlactemia. CONCLUSION: Plasma lactate levels in ambulatory elderly patients with type 2 diabetes receiving metformin therapy did not differ from those in a younger age group. Patients with fasting plasma glucose levels > 130 mg/dL had a 2.8-fold risk of developing hyperlactemia, but none of them developed lactate acidosis.

Pituitary apoplexy after thyrotropin-releasing hormone stimulation test in a patient with pituitary macroadenoma.

Pituitary apoplexy is a rare complication of pituitary tumors. We report a case of a 41-year-old female with acromegaly due to a pituitary macroadenoma, who developed pituitary apoplexy after a thyrotropin-releasing hormone (TRH) 200 microgram intravenous injection stimulation test. Neither emergency computed tomography (CT) scans nor magnetic resonance imaging (MRI), performed 6 hours and 12 hours, respectively, after the active episode, disclosed the evidence of acute hemorrhage or infarction. Two days later, the pituitary mass, removed by transsphenoidal approach, showed ischemic necrosis and acute hemorrhage. The TRH test is generally safe for evaluating pituitary function, but pituitary apoplexy may occur after the procedure. CT and MRI may miss the diagnosis of pituitary apoplexy, especially if performed immediately after the acute episode.