Treatment of severe metformin-associated lactic acidosis with renal replacement therapy and tris-hydroxymethyl aminomethane: a case report.

BACKGROUND: Type B lactic acidosis is a rare but serious side effect of metformin use. The risk of metformin-associated lactic acidosis is elevated in renal or liver impairment, heart failure and in metformin overdose. Metformin-associated lactic acidosis is treated with renal replacement therapy although this can be limited by metformin's large volume of distribution and a patient's hemodynamic instability. Tris-hydroxymethyl aminomethane is a buffer that rapidly equilibrates in liver cells and increases the intracellular pH of hepatocytes. Intracellular alkalosis increases lactate uptake by the liver and can promote gluconeogenesis which results in increased lactate metabolism and decreased lactate production. Unlike intravenous bicarbonate which can worsen acidosis due to carbon dioxide retention and hypocalcemia, tris-hydroxymethyl aminomethane does not generate large amounts of carbon dioxide and can improve cardiac contractility in experimental models. CASE PRESENTATION: We present a case of a 43-year-old African American male who intentionally ingested 480,000 g of metformin. He developed severe metformin-associated lactic acidosis that was refractory to 21 hours of high flux hemodialysis. This was followed by an additional 12 hours of high flux hemodialysis augmented by continuous intravenous infusion of tris-hydroxymethyl aminomethane. After initiating tris-hydroxymethyl aminomethane, the patient had rapid reversal of lactic acidosis and was weaned off vasopressors and mechanical ventilation. CONCLUSIONS: While metformin-associated lactic acidosis can be treated with renal replacement therapy, severe cases of lactic acidosis may not be amenable to renal replacement therapy alone. Through its unique buffer mechanisms, tris-hydroxymethyl aminomethane can be used in conjunction with dialysis to rapidly improve acidosis associated with metformin.

HIV Testing Correlates: U.S. and Foreign Born High-Risk Black Heterosexual Men.

In the U.S., Black men are disproportionately affected by HIV, with some of the highest HIV incidence rates and lowest rates of HIV testing. We examined correlates of HIV testing and knowledge among participants of the Barbershop Talk with Brothers (BTWB) project, an HIV prevention program targeting high-risk sexual behaviors among Black heterosexual men in Brooklyn, New York. Specifically, we examined differences between U.S. vs. foreign-born status and HIV testing rates, HIV knowledge, and socio-demographic factors. Of the 855 men included, the mean age was 33 years and 35.0% were foreign-born. Lifetime HIV testing was reported at 84%, with greater proportion of U.S. vs foreign-born men reporting lifetime (88.6% vs. 75.0%) and recent testing (68.6% vs. 51.0%), p < 0.001. Among foreign-born men, recent HIV testing was associated with lower stigma and greater HIV transmission knowledge than those un-tested. The authors recommend tailored approaches to increasing HIV testing in Black communities, based on nativity and social factors.