digoxin and Hemolysis

Little information is available on the influence of spurious hemolysis on digoxin immunoassays. Seventeen consecutive, non-hemolyzed, sodium-heparin samples were divided in three aliquots. The first was immediately centrifuged and tested for hemolysis index (HI), as well as plasma digoxin on Siemens RXL MAX using the Siemens Dimension Flex and Roche Cobas e601 by electrochemiluminescent (ECLIA) technique. The second and third aliquots were subjected to mechanical hemolysis by aspirating the blood one and two times through a thin needle. The concentration of digoxin measured on Siemens RXL MAX was significantly decreased from aliquot #A, to aliquot #B (-4%), and aliquot #C (-6%), but in none of the hemolyzed specimens the 10% bias was exceeded. No significant variation was observed by measuring plasma digoxin on Roche Cobas.

Topics: Aged; Aged, 80 and over; Digoxin; Female; Hemolysis; Humans; Immunoassay; Luminescent Measurements; Male; Middle Aged

The EXPERT consultation system-building tool, a knowledge-based artificial intelligence program developed at Rutgers University, has been applied to the development of a laboratory consultation system facilitating sequential laboratory testing and interpretation. Depending on the results of a basic panel of laboratory tests, the system requests that specific secondary tests be performed. Input of these secondary findings can result in requests for tertiary testing, to complete the database necessary for interpretation. Interpretation of all results is based upon final inferences from the collected findings through a series of rules, a hierarchical network that yields an efficient production system not easily obtained through conventional programming. The rules included in this model are based upon initial results for total protein, calcium, glucose, total bilirubin, alkaline phosphatase, lactate dehydrogenase, aspartate aminotransferase, thyroxin, hemoglobin, mean corpuscular volume, and the concentrations of four drugs. Pertinent clinical history items included are jaundice, diabetes, thyroid disease, medications, and ethanol. Implementing this system in a laboratory-based accelerated testing program involving outpatients maximized the effective use of laboratory resources, eliminated useless testing, and provided the patient with low-cost laboratory information.

Topics: Adolescent; Adult; Aged; Artificial Intelligence; Bilirubin; Blood Glucose; Chemistry Techniques, Analytical; Diagnosis, Computer-Assisted; Digoxin; Female; Gilbert Disease; Hemoglobins; Hemolysis; Humans; Laboratories; Liver; Male; Middle Aged; Quinidine; Theophylline; Thyroxine

Different concentrations of aqueous preparations of metoclopramide, gaboxadol, cis(Z)-clopenthixol, digoxin and chlorpromazine and of cis(Z)-clopenthixol acetate in Viscoleo have been tested for local toxicity after intramuscular injection in rabbits. The weight of macroscopically changed muscle tissue isolated 3 days after injection was determined. In addition, homogenized injection site muscle tissue was analysed for creatine kinase (CK) activity and by comparison with the CK activity of contralateral muscle tissue, the amount of injection site muscle tissue totally depleted for CK activity was calculated. The substances have also been tested for in vitro toxicity. The concentrations of the substances which caused 100% haemolysis of human erythrocytes or minimal cytotoxicity in cell culture assays using MRC-5 fibroblasts were estimated. Metoclopramide and gaboxadol caused no or only minimal local muscle damage in the rabbits. Metoclopramide caused local bleeding. The four other substances caused concentration-dependent muscle damage. Although there was some deviations, the two in vitro tests reflected reasonably well the in vivo findings. The results of this study suggest that the in vitro tests employed can be useful as screening tests for local toxic effect of intramuscular drug preparations. However, further studies are required before conclusion as to predictability can be drawn. The in vitro methods are inexpensive and quick, especially the haemolysis test.

Topics: Animals; Chlorpromazine; Clopenthixol; Creatine Kinase; Digoxin; Female; Hemolysis; In Vitro Techniques; Injections, Intramuscular; Male; Muscles; Rabbits

Topics: Digoxin; Freezing; Hemolysis; Humans; Hyperbilirubinemia; Immunoenzyme Techniques; Radioimmunoassay

The influence of haemolysis, uraemia and hyperbilirubinaemia on the radioimmunoassay for both digoxin and insulin has been investigated for five separation techniques (dextran/charcoal; coated tube; polyethyleneglycol 4000; sodium sulphite; double antibody). Recoveries, and intra- and interassay precision were calculated. It was demonstrated that even in serum samples with a rather high degree of haemolysis (haemoglobin up to 50 g/l)digoxin can be measured by using each of the five separation techniques without any significant interference. Visible haemolysis (haemoglobin above 200 mg/l) leads either to disturbance or to a complete failure of insulin radioimmunoassays with all separation techniques. This effect can be largely neutralized, and precision improved, by using N-ethylmaleimide. With the exception of the coated tube separation technique the intraassay precision has a CV of less than 10%, and the interassay CV is between 10 and 20%. Elevated urea concentrations interfered in the digoxin radioimmunoassay only when the coated tube technique was used. The insulin radioimmunoassay, however was affected by high urea when either the double antibody or the coated tube technique was used. Here the intraassay precision also has a coefficient of variation less than 10%, the interassay CV lying between 10 and 20%. Bilirubin influenced the digoxin test when the sodium sulphite separation was used, and it affected the insulin determinations with polyethyleneglycol 4000 and sodium sulphite. The intra- and interassay precision were however also around 10% and between 10 and 20% respectively. Compared with the interassay precision of 15% CV for digoxin and 13% for insulin for a pool-serum from blood donors, the decrease of interassay precision caused by haemolysis, uraemia and hyperbilirubinaemia was insignificant.

Topics: Animals; Bilirubin; Digoxin; Ethylmaleimide; Guinea Pigs; Hemolysis; Humans; Insulin; Rabbits; Radioimmunoassay; Urea; Uremia

We describe the application of the microencapsulated-antibody technique to the radioimmunoassay of digoxin in serum. Droplets of emulsified rabbit antibody are microencapsulated in a semipermeable nylon membrane by an interfacial polymerization technique. The antibody microcapsules are incubated with 125I-labeled digoxin and unlabeled digoxin for 15 min at 37 degrees C, then free and bound digoxin are separated by centrifugation. Subtherapeutic, therapeutic, and toxic concentrations of digoxin in sera can be determined, with use of a standard curve prepared by use of known amounts of digoxin. With this technique we obtained an intra-laboratory correlation coefficient of 0.945 for 100 patients' sera and one of 0.940 for interlaboratory results for 21 sera (10 laboratories) when compared to a routine clinical laboratory radioimmunoassay for digoxin. Icterus, lipemia, hemoglobin, or disproteinemia had no effect on the analytical recovery of digoxin. The standard curve was linear to 6 microgram/L; the sensitivity was 0.25 microgram/L.

Topics: Antibodies; Bilirubin; Digoxin; gamma-Globulins; Hemolysis; Humans; Hyperlipidemias; Membranes, Artificial; Radioimmunoassay; Triglycerides

We applied the Enzyme Multiplied Immunoassay Technique (EMIT; Syva Corp., Palo Alto, CA) for determination of serum digoxin to the ABA-100 bichromatic analyzer. Assay conditions were almost exactly as prescribed for the manual procedure, but the ABA-100 offers high automation, smaller reagent volumes, and shorter reaction time. Precision studies gave CV's of less than 10%. Sixty patients' samples, analyzed for digoxin by radioimmunoassay and this enzyme immunoassay, gave a correlation (r) of 0.941. Results obtained with the ABA-100 were apparently slightly higher. One kit provides reagents for 250 assays, as compared to 70 assays with the manual procedure. In an emergency situation a result will be available about 60 min after the patient's sample is received; one operator can analyze about 120 samples in 8 h.

Topics: Digoxin; Hemolysis; Humans; Hyperlipidemias; Immunoenzyme Techniques; Jaundice; Radioimmunoassay; Reagent Kits, Diagnostic

This study is based on a double blind interlaboratory comparison between radioimmunoassay and E.L.I.S.A. digoxin determination. The correlation between digoxin values found with these two methods is good (r = 0.96 for therapeutic and toxic ranges 1,0 ng/ml - 5,5 ng/ml). The results indicate good repeatability, reproducibility and precision. The determination by E.L.I.S.A. can be performed with sera or plasma. The presence of haemolysis makes no appreciable difference in results. No variation is observed when different kits are used from an identical lot. However digoxin gives an important cross reactivity with digitoxin in Enzymeimmunoassay. Therefore it is necessary to know exactly the digitalis glycoside before the determination in order to avoid significant error.

Topics: Digoxin; Enzyme-Linked Immunosorbent Assay; Hemolysis; Methods; Radioimmunoassay

Topics: Cardiac Glycosides; Deslanoside; Digoxin; Erythrocyte Count; Hemolysis; Humans; Lanatosides; Radioimmunoassay

The results of parallel determinations of digoxin in the sera of non selected patients (n = 104) by enzyme immunoassay (EMIT-EIA) and radioimmunoassay (J-125 labeled RIA) were compared with each other. The determinations revealed considerably different concentrations; the values determined by EIA were statistical lower (for EIA 1.09 +/- 0.99 ng/ml, for RIA 1.34 +/- 1.01 ng/ml, p less than 0.01). In sera with hemolysis and in sera of patients with hyperlipidemia and uremia false-negative results were found by EIA. After elimination of these sera an exact concordation of the values of both the methods was obtained (for EIA 1.12 +/- 1.01 ng/ml, for RIA 1.12 +/- 1.02 ng/ml, r = 0.95).

Topics: Digoxin; False Negative Reactions; Glucosephosphate Dehydrogenase; Hemolysis; Humans; Hyperlipidemias; Immunoenzyme Techniques; Radioimmunoassay; Uremia

We present a comparative evaluation of two commercial kits, the "Quantitope" and "GammaCoat," for radioimmunoassay of digoxin in serum. These kits, in which iodine-125 is used as a label, proved to suitable for digoxin assay as determined by their reproducibility, sensitivity, precision, and a regression analysis. Hemolysis, lipemia, and icterus did not affect results. However, in some cases hypoalbuminemia falsely lowered the assayed digoxin concentration. Recovery of pure digoxin added to native patients' sera having low albumin concentration (24-28 g/liter) ranged from 67-105% with the Quantitope kit and 70-110% with the GammaCoat kit. Low serum albumin concentration did not always decrease the recovery of digoxin; this effect varied from serum to serum, which may indicate that there are factors other than albumin that affect the assay of digoxin.

Topics: Digoxin; Evaluation Studies as Topic; Hemolysis; Humans; Iodine Radioisotopes; Jaundice; Radioimmunoassay; Serum Albumin; Triglycerides

Topics: Digoxin; gamma-Globulins; Gentamicins; Hemolysis; Humans; Immune Sera; Mathematics; Pharmaceutical Preparations; Radioimmunoassay; Time Factors; Tritium

Topics: Absorption; Ascorbic Acid; Bilirubin; Color; Digoxin; Hemolysis; Hydrogen Peroxide; Iodine Radioisotopes; Quaternary Ammonium Compounds; Radioimmunoassay; Scintillation Counting; Triiodothyronine; Tritium

Topics: Adenosine Triphosphatases; Adult; Anemia, Hemolytic; Anemia, Hemolytic, Congenital Nonspherocytic; Bilirubin; Blood Cell Count; Coombs Test; Digoxin; Erythrocytes; Female; Haptoglobins; Hemoglobins; Hemolysis; Homozygote; Humans; Infant; Magnesium; Male; Osmotic Fragility; Pedigree; Potassium; Sodium

Topics: Digoxin; Hemolysis; Methods; Radioimmunoassay; Tritium

Topics: Animals; Bilirubin; Blood Proteins; Digoxin; Drug Stability; Hemolysis; Humans; Immune Sera; Iodine Isotopes; Luminescent Measurements; Methods; Protein Binding; Rabbits; Radioimmunoassay; Serum Albumin; Succinates; Temperature; Time Factors; Tritium; Uremia