oxalates and Acidosis--Lactic

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.

Topics: Acidosis, Lactic; Anti-HIV Agents; Blood Preservation; Blood Specimen Collection; Didanosine; HIV Infections; Humans; Lactates; Lamivudine; Multicenter Studies as Topic; Oxalates; Randomized Controlled Trials as Topic; Reverse Transcriptase Inhibitors; Sodium Fluoride; Specimen Handling; Stavudine; Time Factors; Zidovudine

We present a case of a patient with short bowel syndrome in a hemodialysis program, with recurrent episodes of serious acidosis. The presence of a D-lactic acidosis peak secondary to bacterial overgrowth in the intestine was discovered during an acute episode of acidosis, with neurological affection. The detection of acidosis in predialysis measurements and the acute episodes of acidosis, made it necessary to administer bicarbonate to the patient and give him additional hemodialysis sessions.

Topics: Acidosis, Lactic; Adult; Bicarbonates; Brain Diseases, Metabolic; Consciousness Disorders; Drug Therapy, Combination; Dysarthria; Gram-Positive Bacteria; Humans; Intestines; Kidney Failure, Chronic; Lactates; Male; Neomycin; Oxalates; Paromomycin; Recurrence; Renal Dialysis; Short Bowel Syndrome; Urinary Calculi

The use of plasma lactate to assess metabolic or circulatory impairment requires definition of critical preanalytical and analytical parameters. Stability has been documented for only 15 min after acquisition when samples were collected with fluoride and transported on ice. We examined time elapsed before analysis, storage temperature, and the antiglycolytic agent used to define preanalytical conditions. Plasma lactate was measured with a Kodak Ektachem 700XR analyzer. In controlled studies on volunteers, storage on ice slowed but did not eliminate the production of lactate; for samples collected with sodium fluoride (F) and potassium oxalate (OX), lactate increased by 0.2 mmol/L after 1 h, then changed little regardless of the storage temperature. For patients' samples collected in F/OX, the mean increase was only 0.15 mmol/L after 24 h. Samples with leukocytosis (neutrophil counts 23 x 10(9)-52 x 10(9)/L) were also stable, with a mean increase of 0.3 mmol/L at 8 h. Use of the antiglycolytic agents F and OX (at 60 and 12 mmol/L, respectively) maintained apparently stable lactate concentrations at room temperature for up to 8 h without special handling.

Topics: Acidosis, Lactic; Blood Specimen Collection; Drug Stability; Glycolysis; Humans; Lactates; Lactic Acid; Oxalates; Sodium Fluoride