title: The effect of long-term storage on measured plasma lactate concentrations and prospective lactate results from a multicenter trial of antiretroviral therapy.
abstract: Plasma lactate measurements are typically performed in real time, limiting their usefulness in multicenter or longitudinal studies. To determine the stability of lactate specimens, blood was drawn in sodium fluoride/potassium oxalate tubes from 13 volunteers before and after 5 min of handgrip exercise to intentionally increase lactate concentrations. Plasma was stored at -70 degrees C. Aliquots were assayed in real time and after 1, 3, 6, 9, 12, 18, and 24 months. Real-time lactate concentrations measured at baseline ranged from 0.52 to 2.23 mmol/L before and from 2.91 to 11.04 mmol/L after handgrip exercise. Using a linear mixed model, the estimated change from baseline at month 24 was 1.67% (95% confidence interval, -0.70% to 4.03%) for pre-exercise samples and 0.39% (95% CI, -1.13% to 1.91%) for post-exercise samples. Stored serial specimens from 232 HIV-infected subjects in a multicenter trial of antiretroviral therapy were also assayed centrally. Among those, median plasma lactate increased from baseline to 64 weeks by 0.4 mmol/L with zidovudine+lamivudine treatment and by 0.6 mmol/L with didanosine+stavudine (each p<0.001 from baseline; p=0.04 for difference between groups over time). When performed as in this study, frozen storage with central batch lactate analysis is appropriate for prospectively collected samples in multicenter trials.
authors.affiliation: Department of Medicine and Division of Infectious Diseases, Indiana University School of Medicine, Wishard Memorial Hospital, 1001 W. 10th Street, Suite OPW-430, Indianapolis, IN 46202, USA. mpdube@iupui.edu
authors.forename: Michael P
authors.initials: MP
authors.lastname: Dubé
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Kitch
authors.forename: Robert A
authors.initials: RA
authors.lastname: Parker
authors.forename: Beverly L
authors.initials: BL
authors.lastname: Alston-Smith
authors.forename: Kathleen
authors.initials: K
authors.lastname: Mulligan
mesh_terms: D000140:Acidosis, Lactic / Q000097:blood; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D001793:Blood Preservation / Q000379:methods; D001800:Blood Specimen Collection / Q000379:methods*; D016049:Didanosine / Q000627:therapeutic use; D015658:HIV Infections / Q000097:blood* / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D007773:Lactates / Q000097:blood*; D019259:Lamivudine / Q000627:therapeutic use; D015337:Multicenter Studies as Topic; D010070:Oxalates; D016032:Randomized Controlled Trials as Topic; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use; D012969:Sodium Fluoride; D013048:Specimen Handling; D018119:Stavudine / Q000627:therapeutic use; D013997:Time Factors; D015215:Zidovudine / Q000627:therapeutic use
chemical_list: D019380:Anti-HIV Agents; D007773:Lactates; D010070:Oxalates; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine; D015215:Zidovudine; D012969:Sodium Fluoride; D018119:Stavudine; D016049:Didanosine