Development of an objective tool for the diagnosis of myxedema coma.

Myxedema coma, a rare entity, with a reported 25%-65% mortality had no objective criteria for making the diagnosis when we began our study. We developed an objective screening tool for myxedema coma to more easily identify patients and examine the best treatment method in future prospective studies to reduce the mortality of this entity. We conducted a retrospective chart review to find all patients aged ≥18 years admitted with myxedema coma from January 1, 2005 through June 13, 2010 at Indiana University Health Methodist Hospital. On the basis of both our retrospective chart review and on literature accounts, we identified 6 criteria to diagnose myxedema coma. We identified 10 patients initially diagnosed with myxedema coma and established a control group consisting of 13 patients identified with altered mental status and increased thyroid-stimulating hormone (TSH) levels. The 6 variables we created for the screening tool were heart rate, temperature, Glasgow coma scale, TSH, free thyroxine, and precipitating factors. The screening tool has a sensitivity and specificity of about 80%. We ran a logistic regression model using the 10 study patients and 13 controls with the 6 variables. No variables alone significantly contributed to the model. However, the overall model was highly significant (P = 0.012), providing strong support for a scoring system that uses these variables simultaneously. This screening tool enables physicians to rapidly diagnose myxedema coma to expedite treatment. A more refined diagnostic tool may be used in future clinical studies designed to determine the optimal treatment.

Streptozotocin is equally diabetogenic whether administered to fed or fasted mice.

Streptozotocin (STZ) is a selective pancreatic ß cell toxin used to generate experimental hyperglycemia in rodent models. Several laboratory animal protocols suggest that STZ be administered to fasted rodents to minimize competition between STZ and glucose for low affinity GLUT2 transporters on ß cells. However, whether the diabetogenic effects of multiple low dose (MLD)-STZ administration are enhanced by fasting has not been addressed. Given that repeated bouts of fasting can cause undue metabolic stress in mice, we compared the efficacy of MLD-STZ injections (50 mg/kg body weight daily for 5 days) to induce experimental hyperglycemia in both NOD/SCID/γchain(null) and C57BL/6J mice that were either ad libitum fed (STZ-Fed) or that had been fasted for 6 h (STZ-Fasted) prior to the time of STZ administration. Both STZ-Fed and STZ-Fasted mice had significantly worse glucose tolerance than vehicle-treated control mice 10 days after initiation of the MLD-STZ regimen. In C57BL/6J mice, fasting glucose levels, serum insulin levels, ß cell mass, and glucose disposal during intraperitoneal glucose tolerance tests (IPGTTs) were indistinguishable between STZ-Fed and STZ-Fasted mice 20 days after MLD-STZ. The glucose intolerant phenotypes persisted for 20 weeks thereafter, irrespective of whether C57BL/6J mice were fed or fasted at the time of STZ injections. However, STZ-Fasted C57BL/6J mice experienced significant weight loss during the repeated bouts of fasting/re-feeding that were required to complete the MLD-STZ protocol. In summary, induction of experimental hyperglycemia can be achieved using the MLD-STZ protocol without repeated bouts of fasting, which have the potential to cause metabolic stress in laboratory mice.