Severe jaundice with life-threatening liver failure after Kratom use: Reversed by plasma exchange.

Kratom is an herbal supplement which is used for its stimulating properties and pain reduction due to interaction with opioid receptors. Kratom overdose may cause fatality. A 56-year-old man was admitted to the emergency department with severe jaundice and liver failure. His total bilirubin reached at 70.6 mg/dL, but extensive workup did not show any liver mass. Family informed that the patient was taking Kratom. Plasma exchange was suggested as an unconventional therapy and consent from the patient was obtained because this procedure has never been performed to treat Kratom toxicity before. After four procedures, his total bilirubin was reduced to 23.9 mg/dL and his clinical condition improved significantly. Finally on day 5 he was discharged at stable condition with a total bilirubin value of 21.3 mg/dL. There is no antidote for Kratom, and treatment is supportive. To our knowledge this is the first report of reversing Kratom poisoning using plasma exchange.

Prevention of potential delayed hemolytic transfusion reaction in two sickle cell patients using intravenous immunoglobulins and steroids before and after red blood cell exchange with antigen positive units and review literature.

Emergent Red Blood Cell (RBC) exchange is indicated in sickle cell disease (SCD) patients with severe acute chest syndrome. However, fully matched RBC units may not be available for patients with multiple RBC antibodies. Intravenous immunoglobulin (IVIG) and steroids were reported for preventing potential delayed hemolytic transfusion reaction (HTR) in simple transfusion of antigen-positive RBCs. We investigated the efficacy and safety of IVIG and steroids in two SCD patients presented with acute chest syndrome receiving RBC exchange with multiple incompatible units. The first patient had multiple historical alloantibodies, including anti-Jsb, although none of them were reactive. IVIG (1 g/kg) was given before and after RBC exchange with methylprednisolone (500 mg IV) one hour before exchange. Her sickle hemoglobin (HbS) was reduced from 89.4% to 17.4% after the exchange with five Jsb-positive units. The patient improved clinically without acute or delayed hemolysis. The second patient had reactive anti-Jsb on two different admissions 18 months apart. Only one of the sixteen units used in the exchanges was Jsb negative. He received the same IVIG regimen during both admissions but 100 mg IV hydrocortisone instead of methylprednisolone. His HbS was reduced from 63.4% to 22.4% after the first exchange. Significant clinical improvements were achieved after both exchanges. No delayed HTR was observed. Our experience of these two patients suggested that IVIG and steroids may be used in preventing potential delayed HTR in some SCD patients with rare antibodies receiving large amounts of antigen-positive RBC products.

Significant Improvement in Digoxin Immunoassays Over Four Decades: Newer Assays are Less Affected by Interferences.

BACKGROUND: Digitalis glycosides derived from foxglove plants have been used for medicinal purposes since the 16th century. Currently, digoxin derived from foxgloves is used clinically. Owing to the narrow therapeutic range, therapeutic drug monitoring is essential; however, digoxin immunoassays suffer from interference. METHODS: The issue of interference was reviewed for both older polyclonal antibody-based digoxin assays and newer monoclonal antibody-based digoxin assays. A literature search was conducted using PubMed, ScienceDirect, Scopus, Web of Science, and ResearchGate for studies on digoxin immunoassays published in the English language from 1969 to the present. RESULTS: Radioimmunoassays for digoxin in the 1970s and, later, first-generation nonradioimmunoassay methods were liable to several interferences, including digoxin-like immunoreactive substances, spironolactone, potassium canrenoate, and various digoxin metabolites. However, for the last 10-15 years, next next-generation digoxin immunoassays have been virtually free from such interferences. Nevertheless, certain herbal supplements, as well as both Digibind and DigiFab, interfere with serum digoxin measurement, even with the more recently developed digoxin assays. CONCLUSIONS: More recently introduced monoclonal antibody-based digoxin assays are superior to the older polyclonal antibody-based digoxin assays.

Utility of Therapeutic Drug Monitoring in Identifying Clinically Significant Interactions Between St. John's Wort and Prescription Drugs.

BACKGROUND: The general population widely uses herbal medicines, as they are regarded as effective and safe. St. John's wort, which is an effective herbal antidepressant, exhibits both pharmacokinetic and pharmacodynamic interactions with several drugs. The aim of this review was to highlight the clinically significant interactions of St. John's wort with drugs that require to be monitored to assess their therapeutic effect. METHODS: Published literature was searched using electronic databases, such as MEDLINE, PubMed, and Elsevier ScienceDirect using terms such as "herbal medicine," "herbal toxicity," "legislation herbal medicine," "drug-herb interactions," "St. John's wort," and "St. John's wort-drug interactions." Searches were limited to the English language, and there was no restriction on the date of publication. RESULTS: St. John's wort exhibits a number of pharmacokinetic and pharmacodynamic interactions with drugs. The most dangerous interactions occurred when used concurrently with the immunosuppressants, cyclosporine, and tacrolimus (treatment failure or organ rejection) or warfarin (treatment failure resulting in thromboembolic events) or antiretroviral agents (treatment failure and the emergence of new viral variants that are resistant to conventional drugs). CONCLUSIONS: Patients should consult their health care providers before consuming herbal supplements, especially St. John's wort, to avoid potentially dangerous drug-herb interactions.

Perioperative therapeutic plasma exchange in a patient with rare Factor XIII inhibitor.

INTRODUCTION: Factor XIII deficiency is a rare bleeding disorder which could be severe if inherited or less severe if acquired. We report a case of acquired Factor XIII inhibitor in a 75-year-old male with a suspicious left renal mass treated perioperatively with therapeutic plasma exchange (TPE). PATIENT AND METHOD: To perform kidney biopsy and ablation of the renal mass, six daily TPE treatments were performed before and after biopsy to minimize bleeding risk because the patient did not respond to drug therapy. Both thromboelastography (TEG) and laboratory-based coagulation tests were performed to assess coagulation status prior to and after TPE. RESULTS: The biopsy indicated oncocytoma which was removed by surgical procedure. Factor XIII activity remained below 15 % throughout TPE treatments, but Factor XIII inhibitor titer reduced from initial positive value of 1:40 to negative following the third TPE and remained negative through the sixth TPE. Unfortunately, the inhibitor titer was positive at 1:20 in the fifth month and 1:5 in the sixth month during follow-up. CONCLUSIONS: TPE is useful in removing XIII inhibitory factor, but the effects are only short term.

Significant discordance between point of care BNP values obtained by the i-STAT and the Beckman DXI 800, causing confusion in patient management when both methods are used interchangeably by clinicians.

B-type natriuretic peptide (BNP) is used as a biomarker of heart failure. In our hospital point of care (POCT) BNP test is performed in EDTA whole blood using i-STAT (Abbott Laboratories, Abbott Park, IL, USA) and in the clinical laboratory using EDTA plasma and the DXI 800 analyzer (Beckman, Brea, CA, USA). We compared BNP values in 88 patients obtained by using the i-STAT followed by using the DXI 800. The time difference between the two analyses varied from 32 min to less than 12 h. In addition, 11 specimens were simultaneously analyzed for BNP using both the i-STAT and the DXI 800 analyzer. Plotting BNP concentrations obtained by the DXI 800 in the x-axis (reference method) and the i-STAT values in the y-axis, we observed the following regression equation; y = 1.4758 x + 23.452 (n = 88, r = 0.96), indicating significant positive bias with the i-STAT. In addition, we also observed significant differences between BNP values obtained by the i-STAT and the DXI 800 in 11 specimens analyzed simultaneously. Therefore, clinicians should not use BNP concentrations obtained by the i-STAT interchangeably with BNP concentrations obtained by the DXI 800 analyzer for patient management.

Severe complications in a 25-year-old male after brown recluse spider bite treated by therapeutic plasma exchange: A case report and review of other case studies.

Although in the majority of patients (90%), the bite wound of brown recluse spider resolves spontaneously, some patients may experience a severe reaction requiring hospitalization. A 25-year-old male developed severe hemolytic anemia, jaundice, and other complications following a brown recluse spider bite on his posterior right thigh. He was treated with methylprednisolone, antibiotics, and red blood cells (RBCs) transfusion without response. Therapeutic plasma exchange (TPE) was added to the treatment regimen, and his hemoglobin (Hb) was eventually stabilized, leading to significant clinical improvement. The beneficial effect of TPE in the current case was compared to three other reported cases. We recommend close monitoring of Hb levels in patients with systemic loxoscelism during the first week after brown recluse spider bite and early implementation of TPE in the management of severe acute hemolysis when patients do not respond to usual treatment modalities and RBC transfusion.

Digitally enabled hemovigilance allows real time response to transfusion reactions.

BACKGROUND: Transfusion carries a risk of transfusion reaction that is often underdiagnosed due to reliance on passive reporting. The study investigated the utility of digital methods to identify potential transfusion reactions, thus allowing real-time intervention for affected patients. METHOD: The hemovigilance unit monitored 3856 patients receiving 43,515 transfusions under the hemovigilance program. Retrospective comparison data included 298,498 transfusions. Transfusion medicine physicians designed and validated algorithms in the electronic health record that analyze discrete data, such as vital sign changes, to assign a risk score during each transfusion. Dedicated hemovigilance nurses remotely monitor all patients and perform real-time chart reviews prioritized by risk score. When a reaction is suspected, a hemovigilance trained licensed clinician responds to manage the patient and ensure data collection. Board-certified transfusion medicine physicians reviewed data and classified transfusion reactions under various categories according to the Centers for Disease Control hemovigilance definitions. RESULTS: Transfusion medicine physicians diagnosed 564 transfusion reactions (1.3% of transfusions)-a 524% increase compared to the previous passive reporting. The rapid response provider reached the bedside on average at 12.4 min demonstrating logistic feasibility. While febrile reactions were most diagnosed, recognition of transfusion-associated circulatory overload demonstrated the greatest relative increase. Auditing and education programs further enhanced transfusion reaction awareness. DISCUSSION: The model of digitally-enabled expert real-time review of clinical data that prompts rapid response improved recognition of transfusion reactions. This approach could be applied to other patient deterioration events such as early identification of sepsis.

Challenged comparison of tacrolimus assays.

Monitoring tacrolimus trough concentrations is important for optimal immunosuppression in solid organ transplant recipients. Available assays generally correlate well with each other but little attention is given to patients in whom tacrolimus metabolite concentrations might be elevated, which could lead to artificially increased tacrolimus concentrations assessed by cross-reacting immunoassays. We addressed this hypothesis by investigating the correlation between four different assays (two immunoassays and two mass-spectrometry assays) in both a population with normal and a population with high dose requirements. Routine blood samples were collected in 37 control (CO) and 72 high dose patients (HD). Tacrolimus was measured with a CMIA, an ECLIA and two LCMS assays. Results were investigated using Deming regression analysis, Pearson correlation coefficients, Bland-Altman plots and by calculating bias. The CMIA demonstrated a positive bias of 23-26% compared with both LCMS assays. The correlation between CMIA and LCMS assays was good for the CO (r = 0.96) but less so for the HD group (r = 0.91). The ECLIA showed a positive bias of 11-13% compared with both LCMS assays. The correlation between ECLIA and LCMS assays was also good for the CO (r = 0.95) but again less for the HD group (r = 0.93). The correlation for both LCMS assays was excellent for either group (r > 0.99) with no bias. CMIA, ECLIA and LCMS assays for tacrolimus therefore correlate well for trough concentrations from solid organ transplant recipients. However, inter-assay differences exist, which seem more pronounced in patients who need a high dose of tacrolimus to reach a trough concentration in the therapeutic range.

Review of the Preanalytical Errors That Impact Therapeutic Drug Monitoring.

PURPOSE: Preanalytical errors comprise the majority of testing errors experienced by clinical laboratories and significantly impact the accuracy of therapeutic drug monitoring (TDM). METHODS: Specific preanalytical factors in sample timing, collection, transport, processing, and storage that lead to errors in TDM were reviewed. We performed a literature search using several scientific databases including PubMed, ScienceDirect, Scopus, Web of Science, and ResearchGate for human studies published in the English language from January 1980 to February 2021, reporting on TDM and the preanalytical phase. RESULTS: Blood collection errors (ie, wrong anticoagulant/clot activator used, via an intravenous line, incorrect time after dosing) delay testing, cause inaccurate results, and adversely impact patient care. Blood collected in lithium heparin tubes instead of heparin sodium tubes produce supertoxic lithium concentrations, which can compromise care. Specimens collected in serum separator gel tubes cause falsely decreased concentrations due to passive absorption into the gel when samples are not processed and analyzed quickly. Dried blood spots are popular for TDM as they are minimally invasive, allowing for self-sampling and direct shipping to a clinical laboratory using regular mail. However, blood collection techniques, such as trauma to the collection site, filter paper fragility, and hematocrit (Hct) bias, can adversely affect the accuracy of the results. Volumetric absorptive microsampling is a potential alternative to dried blood spot that offers fast, volume-fixed sampling, low pain tolerance, and is not susceptible to Hct concentrations. CONCLUSIONS: The identification of preanalytical factors that may negatively impact TDM is critical. Developing workflows that can standardize TDM practices, align appropriate timing and blood collection techniques, and specimen processing will eliminate errors.

Biotin interference in TSH, FT4, and FT3 assays based on the LOCI technology: Identifying interference by dilution.

BACKGROUND: Although biotin interferences in TSH, FT3, FT4, and other biotinylated antibody-based assays manufactured by Roche Diagnostics have been well studied, there are relatively few reports on biotin interference in biotin-based assays manufactured by other companies. We investigated biotin interferences in TSH, FT4, and FT3 assays based on the LOCI (luminescent oxygen channeling assay) technology using the Dimension Vista 1500 analyzer (Siemens). METHODS: We prepared four serum pools using leftover specimens. Three serum pools were prepared initially for the original study but the 4th pool was prepared three months later. The aliquots of serum pool one and two were supplemented with various amounts of biotin (50 -1200 ng/mL) followed by determination of TSH, FT4, and FT3 concentrations. The aliquots of third pool were also supplemented with biotin to investigate whether 1:3 dilution could identify biotin interference. Aliquots of serum pool four were supplemented with biotin in order to study reproducibility of our original data. RESULTS: We observed significantly elevated FT3 levels at biotin concentration of 100 ng/mL. In contrast, FT4 levels were falsely elevated but TSH levels were falsely decreased at a biotin level of 500 ng/mL. We also observed nonlinearity in dilution experiment. CONCLUSIONS: We conclude that FT3 assay is most susceptible to biotin interference (threshold: 100 ng/mL) while the FT4 and TSH assays are less affected (threshold: 500 ng/mL). In addition, we also observed nonlinearity upon 1:3 dilution, which may indicate biotin interference (or interference from other compounds).

Convallatoxin, the active cardiac glycoside of lily of the valley, minimally affects the ADVIA Centaur digoxin assay.

OBJECTIVE: Lily of the valley is a poisonous plant due to the presence of the cardiac glycoside convallatoxin which is known to interfere with serum digoxin measurement using the LOCI digoxin assay and other digoxin assays. We evaluated potential interference of convallatoxin as well as extract of lily of the valley with the ADVIA Centaur digoxin assay by comparing results obtained using the LOCI digoxin assay. MATERIALS AND METHODS: Aliquots of a drug-free serum pool and a digoxin serum pool were supplemented with nanograms to 1 µg quantities of convallatoxin or 1.0 and 2.5 µL of lily of the valley extract per milliliter of serum followed by measurement of digoxin concentrations using the LOCI and ADVIA Centaur digoxin assays. RESULTS: Apparent digoxin concentrations were minimal using the ADVIA Centaur digoxin assay when aliquots of drug-free serum were supplemented with convallatoxin or extract of lily of the valley but apparent digoxin levels were very high using the LOCI digoxin assay. Moreover, minimal interference in serum digoxin measurement using the ADVIA Centaur digoxin assay was observed when aliquots of serum digoxin pool were further supplemented with lily of the valley extract. As expected, the LOCI digoxin assay showed significant interference of convallatoxin in serum digoxin measurement. CONCLUSIONS: Significant interference of convallatoxin in serum digoxin measurement using the LOCI digoxin assay could be minimized using the ADVIA Centaur digoxin assay.

Suitability of the DRI Hydrocodone/Hydromorphone Immunoassay in the Clinical Environment at a Lower Cutoff: Validation With LC-MS/MS Analysis.

BACKGROUND: We evaluated the analytical performance of the DRI hydrocodone/hydromorphone assay by comparing semiquantitative values obtained by this assay with values obtained by a liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) method. We also evaluated the possibility of lowering the cutoff of the DRI assay from 300 to 100 ng/mL. METHODS: We compared semiquantitative values obtained by the DRI assay in 97 specimens with values obtained by the LC-MS/MS method including 10 specimens containing hydrocodone and/or hydromorphone concentrations between 105.0 and 145.0 ng/mL (determined by LC-MS/MS) to determine the sensitivity at 100 ng/mL. In addition, several opioids at a concentration of 5000 ng/mL were also analyzed by the DRI assay to determine its specificity. RESULTS: We observed no false-negative result using the DRI immunoassay in 96 specimens that showed semiquantitative values at 100 ng/mL or higher. However, one specimen containing 110 ng/mL of hydrocodone was false negative with the DRI assay (semiquantitative value 88 ng/mL, below 100 ng/mL cutoff). The semiquantitative values produced by DRI showed poor correlation with values determined by the LC-MS/MS method. The sensitivity of the DRI assay at 100 ng/mL was 90%, and the assay was very specific showing minimal cross-reactivity only with oxycodone and oxymorphone. CONCLUSIONS: DRI immunoassay for hydrocodone/hydromorphone is a cost-effective method of screening urine specimens in the clinical environment at a lower cutoff of 100 ng/mL.

Comparison of SemiQuantitative Cotinine Values Obtained by the DRI Immunoassay and Values Obtained by a Liquid Chromatography-Tandem Mass Spectrometry-Based Method: The DRI Immunoassay is Suitable for Screening Purposes Only Because Semiquantitative Values May Be Unreliable.

BACKGROUND: DRI cotinine assay is suitable only for screening for cotinine in urine specimens. We studied the reliability of DRI cotinine semiquantitative values by comparing them with the cotinine concentration obtained with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. METHODS: Semiquantitative cotinine concentrations in 39 urine specimens obtained by the DRI immunoassay were compared with cotinine concentrations obtained by LC-MS/MS. RESULTS: The DRI cotinine assay consistently overestimated cotinine values obtained by the LC/MS/MS method (y = 1.1529 x + 252.24, n = 39, R2 = 0.8899) indicating that semiquantitative values obtained using the DRI assay may be unreliable. However, no false-negative results were observed using the DRI assay. CONCLUSION: DRI cotinine assay is suitable only for screening cotinine in urine specimens.

Comparison of Response of DRI Oxycodone Semiquantitative Immunoassay With True Oxycodone Values Determined by Liquid Chromatography Combined With Tandem Mass Spectrometry: Sensitivity of the DRI Assay at 100 ng/ml Cut-Off and Validity of Semiquantitative Value.

OBJECTIVE: Oxycodone is a widely used opioid for pain management and patient's compliance with therapy is often monitored by using oxycodone immunoassay. The performance of the DRI oxycodone immunoassay was compared with liquid chromatography combined with tandem mass spectrometry (LC/MS/MS) assay. MATERIALS AND METHODS: In 48 urine specimens collected from patients taking oxycodone, urinary oxycodone concentrations were determined using LC/MS/MS and the DRI oxycodone immunoassay for application on the Cobas c 501 analyzer (Roche Diagnostics, Indianapolis, IN). RESULTS: Out of 48 specimens, 14 specimens showed oxycodone value less than 100 ng/ml, seven specimens had low positive values (between 101 and 165 ng/ml) and all other specimens had values 165 to 1789 ng/ml using the LC/MS/MS assay. The DRI oxycodone assay successfully identified all oxycodone specimens with oxycodone concentrations over the 100 ng/ml. In addition, the DRI assay also showed positive response in 11 out of 14 specimens with oxycodone values less than 100 ng/ml. However, semiquantitative values obtained by the DRI assay did not match with true oxycodone and metabolite oxymorphone concentrations combined obtained by using LC/MS/MS. CONCLUSIONS: DRI oxycodone immunoassay at 100 ng/ml is a reliable immunoassay for analysis of oxycodone in urine.

Zinc Sulfate, a Recently Introduced Urinary Adulterant Can Invalidate Urine Cotinine Test Using Immunoassay but Has Less Effect on Liquid Chromatography Combined With Tandem Mass Spectrometry-Based Test.

OBJECTIVE: Zinc sulfate is a recently introduced urinary adulterant, which causes false-negative results with immunoassays used for screening drugs of abuse in urine but whether zinc sulfate also could invalidate urine cotinine assay using immunoassay or liquid chromatography combined with mass spectrometry has never been studied. DESIGN AND METHOD: Four urine pools containing none detected to high levels of cotinine were analyzed using DRI cotinine immunoassay on the Olympus 640 analyzer as well as using liquid chromatography combined with tandem mass spectrometry. Specimens were reanalyzed after supplementing with various amounts of zinc sulfate that are known to invalidate immunoassays used for drugs of abuse testing. RESULTS: Zinc sulfate in all concentrations studied caused false-negative results using immunoassays, but zinc sulfate also reduced cotinine values by approximately 2.1%-38.4% when analyzed using liquid chromatography combined with mass spectrometry. CONCLUSIONS: Zinc sulfate caused false-negative cotinine result when DRI immunoassay was used and also had small to moderate impact on liquid chromatography combined with tandem mass spectrometry-based assay for urine cotinine.

Limitations of EMIT benzodiazepine immunoassay for monitoring compliance of patients with benzodiazepine therapy even after hydrolyzing glucuronide metabolites in urine to increase cross-reactivity: comparison of immunoassay results with LC-MS/MS values.

BACKGROUND: Benzodiazepines are widely prescribed, and compliance of patients with benzodiazepine therapy is often monitored using urine specimens. Although various commercially available benzodiazepines immunoassays are widely used for compliance monitoring, such immunoassays usually have low cross-reactivity with glucuronide metabolites. We studied the effect of hydrolyzing such glucuronide before analysis to reevaluate suitability of Enzyme multiplied immunoassay technique benzodiazepine immunoassay for monitoring compliance with benzodiazepine therapy. METHODS: In 31 urine specimens collected from patients taking benzodiazepines, the true analyte concentrations were determined (after hydrolyzing glucuronide metabolites using beta-glucuronidase) using liquid chromatography-tandem mass spectrometry. These urine specimens were reanalyzed using EMIT benzodiazepine assay (Flex Reagent Cartridge; Siemens Diagnostics) and Vista analyzer. RESULTS: We observed false negative test results with EMIT in 11 of 31 specimens analyzed where liquid chromatography-tandem mass spectrometry values were above the 200 ng/mL cutoff concentration, but EMIT benzodiazepine assay showed a negative result, indicating that despite hydrolysis of the specimen to liberate parent drug (glucuronide metabolite often has poor cross-reactivity), the false negative rate using EMIT assay was 35.5%. CONCLUSIONS: Patient compliance with benzodiazepine therapy must be monitored using a chromatographic method.

Effect of Chinese Medicine Danshen and Indian Ayurvedic Medicine Bark of Arjuna Tree on a Relatively New LOCI Digoxin Assay for Application on the Vista 1500 Analyzer.

BACKGROUND: Danshen is a traditional Chinese medicine and bark of Arjuna tree is an Ayurvedic medicine both indicated as heart tonic. Interference of Danshen in serum digoxin immunoassays has been reported but potential interference of extract of bark of Arjuna tree has not been reported. We studied potential interferences of Danshen and bark of Arjuna tree on a relatively new LOCI digoxin assay for application on the Vista 1500 analyzer (Siemens Diagnostics). METHODS: Aliquots of drug-free serum were supplemented with ethyl acetate extract of Danshen (two different brands studied) or aqueous or ethyl alcohol extract of bark of Arjuna tree and apparent digoxin concentrations were measured by the LOCI digoxin assay. In another experiment, aliquots of serum pool containing digoxin were further supplemented with Danshen or bark of Arjuna tree extract and digoxin concentrations were measured again using LOCI digoxin assay. RESULTS: Little apparent digoxin concentration was observed when aliquots of drug-free serum pools were supplemented with Danshen or bark of Arjuna tree extract. When aliquots of serum digoxin pool were further supplemented with these extract, we observed statistically significant negative interference but such differences may not be clinically significant. CONCLUSION: We conclude that LOCI digoxin assay is virtually free from interferences of Danshen and extract of bark of Arjuna tree.

Digoxin immunoassays on the ARCHITECT i2000SR and ARCHITECT c8000 analyzers are free from interferences of Asian, Siberian, and American ginseng.

Asian, Siberian, and American ginseng are known to interfere with serum digoxin measurements using fluorescence polarization technology, Digoxin II and Digoxin III assays (Abbott Laboratories, Green oaks, IL) as well as other digoxin assays. Abbott Laboratories more recently launched two new digoxin assays: iDigoxin, a chemiluminescent microparticle immunoassay for application on the ARCHITECT i1000SR and i2000SR immunoassay analyzers, and cDigoxin, a particle-enhanced turbidimetric inhibition immunoassay for application on the ARCHITECT c4000, c8000, and c1600 clinical chemistry analyzers; and we studied potential interferences of ginsengs with these two assays in vitro. When aliquots of drug-free serum pool treated with activated charcoal were supplemented with extracts of various ginsengs, no significant apparent digoxin values were observed. In addition, when aliquots of the digoxin pool prepared from patients taking digoxin were further supplemented with these ginseng extracts and the digoxin values were re-measured, we observed no statistically significant difference in observed digoxin values compared to the original digoxin value of the pool. These results further establish that relatively new digoxin assays for application on the ARCHITECT analyzers that employ specific monoclonal antibodies against digoxin are free from interferences from Asian, Siberian, and American ginseng.

Inability to Measure M-Protein With Capillary Zone Electrophoresis (CAPPILLARYS 2) in Tracings With NonDiscernable Peaks.

BACKGROUND: We performed a retrospective study to illustrate the challenges with quantifying monoclonal (M)-protein in the cases of serum protein capillary zone electrophoresis (SPCZE) where no discernable peak is apparent. MATERIALS AND METHODS: We retrospectively reviewed 160 serum immunofixation electrophoresis (SIFE) that were performed at Memorial Hermann Hospital-Texas Medical Center between October 2013 and November 2013 and we identified the positive SIFE results. The corresponding SPCZE of the positive SIFE were retrieved and evaluated for the ability to quantify M-proteins in them. We define the ability to quantify M-protein as the ability for the operator of the SPCZE to identify a discernable peak and to be able to manually gate the area under the peak. RESULTS: Twenty-two cases of SIFE detected a monoclonal immunoglobulin. Of the corresponding 22 SPCZE, we could not quantify the M-protein in 6 (27.3%) of the cases. CONCLUSION: We have shown several cases where we were not able to quantify the M-protein with SPCZE. This poses a challenge in the diagnosis and management of these patients.