Testosterone, Dihydrotestosterone, Sex Hormone-Binding Globulin, and Incident Diabetes Among Older Men: The Cardiovascular Health Study.

Context: Although sex hormone-binding globulin (SHBG) and testosterone (T) have been inversely associated with risk of diabetes, few studies have examined dihydrotestosterone (DHT), a more potent androgen than T, in older adults, whose glycemic pathophysiology differs from younger adults. Objective: To determine the associations of SHBG, T, and DHT with insulin resistance and incident diabetes in older adult men. Design: In a prospective cohort study, we evaluated baseline levels of SHBG, T, and DHT using liquid chromatography-tandem mass spectrometry among 852 men free of diabetes and cardiovascular disease in the Cardiovascular Health Study in 1994. Main Outcome: Insulin resistance estimated by Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and insulin sensitivity estimated by the Gutt index in 1996, and incident diabetes (n = 112) ascertained over a mean follow-up of 9.8 years. Results: In linear regression models adjusted for demographics, alcohol consumption, current smoking, body mass index, and other androgens, SHBG [HOMA-IR 0.30 units lower per doubling; 95% confidence interval (CI), 0.08 to 0.52; P = 0.01] and total DHT (HOMA-IR 0.18 units lower per doubling; 95% CI, 0.06 to 0.30; P = 0.01), but not free T (P = 0.33), were inversely associated with insulin resistance. In corresponding Cox proportional hazards models, total DHT was again inversely associated with risk of diabetes (adjusted hazard ratio per doubling, 0.69; 95% CI, 0.52 to 0.92; P = 0.01), but SHBG (hazard ratio, 1.09; 95% CI, 0.74 to 1.59; P = 0.66) and free T (hazard ratio, 1.15; 95% CI, 0.92 to 1.43; P = 0.23) were not. Conclusions: Among older men, higher levels of DHT were inversely associated with insulin resistance and risk of diabetes over the ensuing 10 years, whereas levels of T were not. Future studies are still needed to clarify the role of SHBG in risk of diabetes in this population.

Extracorporeal Membrane Oxygenation Support for Hypokalemia-induced Cardiac Arrest: A Case Report and Review of the Literature.

BACKGROUND: Hypokalemia is a reversible cause of cardiac arrest in patients presenting to the emergency department (ED). Extracorporeal membrane oxygenation (ECMO) is an established technology for cardiopulmonary support with emerging roles in resuscitation. Here, we review the literature of hypokalemic-induced cardiac arrests and discuss one such case successfully managed with ECMO. CASE REPORT: A 23-year-old Central American man who presented to a community ED under federal custody with several days of nausea and vomiting was found to have a serum potassium level of 1.5 mEq/L. Repeat serum potassium level was 1.1 mEq/L upon arrival to our facility. Within 2 h of arrival, despite electrolyte repletion, he suffered cardiac arrest. Advanced cardiac life support was performed for 45 min. ECMO was initiated while active chest compressions were performed. After aggressive potassium repletion, return of spontaneous circulation was achieved and ECMO was eventually discontinued. Further investigation ultimately confirmed the presence of a potassium-wasting nephropathy, for which the patient had been treated with chronic potassium supplementation prior to entering federal custody. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: ECMO is a well-established modality for cardiopulmonary support, with an emerging role for patients in undifferentiated cardiac arrest presenting to the ED. There is a growing interest in the utility of ECMO in these circumstances. This report highlights hypokalemia as an important cause of cardiac arrest, reviews the treatment and causes of hypokalemia, and demonstrates a potential role for ECMO as a critical temporizing measure to provide time for potassium repletion.