IgM monoclonal protein presenting as pseudohypercreatininaemia.
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Antibodies, Monoclonal↗
Biomedical subjects
John Krahn
Publications and source records attributed to John Krahn.
Troponin I testing in dialysis patients presenting to the emergency room: does troponin I predict the 30-day outcome?
BACKGROUND: Troponins are often measured in acutely ill chronic dialysis patients admitted to the emergency room, irrespective of their clinical presentation. The significance of an elevated troponin level in this setting is unclear. METHODS: We identified all chronic dialysis patients presenting over 1 year to a tertiary care hospital emergency room who also had at least one cardiac troponin I (cTnI) level determination. We evaluated presenting complaints, risk factors for cardiac disease, cTnI levels, and major cardiac events (MCE; occurrence of cardiovascular death, myocardial infarction, de novo heart failure, or coronary revascularization) within 30 days by chart review in 149 patients (79 on hemodialysis, 70 on peritoneal dialysis). RESULTS: Chest pain was documented in only 29% of the patients. Twenty-two patients (15%) experienced an MCE. The incidence of an MCE was the same in patients with and without chest pain. A cTnI level >0.1 ng/l was a significant predictor of an MCE (odds ratio 15.2, 95% confidence interval CI 5.26, 43.6). The likelihood ratios for MCEs were 0.32 (CI 0.16, 0.63) for a cTnI level <0.1 ng/l, 0.72 (CI 0.09, 5.5) for cTnI concentrations 0.1-0.3 ng/l, 7.8 (CI 4.2, 15) for a cTnI level >0.3, and 11.7 (CI 4.4, 31) for a cTnI concentration >2.0 ng/l. CONCLUSION: In acutely ill chronic dialysis patients presenting to a hospital emergency room, an elevated cTnI level indicates an increased 30-day cardiac risk, regardless of their clinical presentation.
Aged↗
Osmolality gaps: diagnostic accuracy and long-term variability.
BACKGROUND: The osmolal gap (OG) is a screening test for the detection of toxic volatiles such as methanol and ethylene glycol. We used mean values of patient data to assess the diagnostic accuracy and long-term stability of OG measurements. METHODS: In a prospective study period in 2003, all requests for volatiles had OGs calculated and quality-control samples were analyzed for OG. ROC curves were constructed to determine whether OG could predict the presence of toxic volatiles in serum. This was also done in a retrospective study for data from 1996 to 2004. Our laboratory database was searched for all emergency room patients for the period of 1996 to 2004 who had tests ordered that allowed us to calculate OGs. RESULTS: For the prospective study period in 2003, the ROC areas indicated that we could accurately predict the presence of toxic volatiles but at markedly different decision cutpoints depending on the formula used. These cutpoints ranged from +10 to +33 mosmol/kg. In the retrospective study, the mean OGs in the patient population for each of the 3 formulas increased by 12 mosmol/kg from 1996 to 2004. For this reason, the diagnostic accuracy was poor when all data were analyzed together. CONCLUSIONS: Under properly controlled conditions, the OG has high sensitivity and specificity for detection of poisoning with some volatiles. Over the long term, however, use of the reference interval of -10 to +10 mosmol/kg yields poor diagnostic accuracy because mean OGs are not constant over time. Bedside calculation is not advisable.
Ethylene Glycol↗
Biochemistry testing associated with pregnancy and the newborn period -- a lot has changed since you were a baby!
Everyone has been a newborn, and everyone's mother has been pregnant. Despite the commonality of these events, medical care and the clinical chemistry laboratory's role in it have changed remarkably over the last 50 years. This review is a historical overview of clinical chemistry testing that is related to pregnancy and the newborn period.
Chorionic Gonadotropin↗
A simple method for quantifying fentanyl, sufentanil, or morphine in discard syringes from anesthesia procedures.
Fentanyl, sufentanil, and morphine are commonly used in the conduct of anesthesia. Medical staff working with these drugs are at high risk of addiction. To detect and prevent diversion, a method was developed to quantify these drugs in discard syringes using the BioRad REMEDi HS Drug Profiling System. For fentanyl, the lowest concentration detected is 0.1 microg/mL, and the assay is linear to 5.0 microg/mL; the within-run coefficient of variation (CV) is 0.9% (n = 5), and between-run CV is 2.5% (n = 20). For sufentanil, the lowest concentration detected is 0.5 microg/mL, and the assay is linear to 11.0 microg/mL; the within-run CV is 2.0% (n = 5), and the between-run CV is 2.4% (n = 20). For morphine, the lowest concentration detected is 0.5 microg/mL, and the assay is linear to 10.0 microg/mL; the within-run CV is 11.6% (n = 5), and between-run CV is 11.3% (n = 20). Other drugs commonly used in the operating room were checked for cross-reactivity on the REMEDi HS; none cross-reacted. The REMEDi HS can be used for rapid, accurate quantification of fentanyl, sufentanil, and morphine in discard syringes from anesthesia procedures or related medical applications.
Anesthesia, Intravenous↗