The treatment of tuberculosis usually includes the antibiotic rifampicin, especially in patients with concomitant human immunodeficiency virus infection. Some of these patients are in withdrawal therapy for drug abuse. When opiate screening is carried out in patients receiving rifampicin, false positive results are detected with the kinetic interaction of microparticles in solution method. We evaluated this interference in a Cobas-Integra analyzer and found a 12% cross-reactivity of rifampicin for antibiotic concentrations ranging from 0.19 to 6.08 mumol/l (156 to 5000 micrograms/l). This effect is not explained by the colour of the rifampicin solutions. Calculations assuming first order kinetics of elimination show that more than 18 hours after a single oral dose of 600 mg of rifampicin, a false positive result for opiates could be obtained. This indicates that the risk of a false positive result must always be considered when urine samples from these patients are analyzed.

No abstract

No abstract

The aim of this study was to investigate the biochemical and hematological changes in patients on routine hemodialysis treatment when they were accidentally exposed to moderately high serum aluminum concentrations during a period of time of less than four months. We studied the changes in biochemical and hematological measurements in 33 patients on dialysis in our hospital before and during the exposure to about 0.85 pmol/l of aluminum in dialysis water due to a malfunction of the reverse osmosis system of water purification. Patients showed a decrease in the hemoglobin concentration from 115+/-12.4 g/l to 108+/-12.2 g/l (p=0.026) and in the mean corpuscular hemoglobin concentration from 5.15+/-0.22 to 5.02+/-0.30 mmol/l (p=0.014). Ferritin was decreased from 243+/-192 microg/l to 196+/-163 microg/l (p=0.047) and transferrin saturation from 0.20+/-0.06 to 0.15+/-0.07 (p=0.004). Biochemical measurements related to calcium-phosphate metabolism did not change. Otherwise, all patients showed an increase in serum aluminum from 0.56+/-0.44 to 1.63+/-0.52 micromol/l (p<0.001). No differences were detected in serum aluminum between patients receiving and not receiving oral aluminum salts. Even moderately high aluminum concentrations maintained during a short period of time could produce significant hematological alterations and a depletion of body iron stores before clinical manifestations were evident.

No abstract