Prognostic value of serum cardiac troponin I and T in chronic dialysis patients: a 1-year outcomes analysis

To determine the incidence and prognostic value of increased serum cardiac troponin I and T concentrations over 12 months in chronic hemodialysis patients, we performed a retrospective chart review in 16 patients undergoing chronic renal hemodialysis randomly selected from the Regional Kidney Disease Program without prior knowledge of their cardiac status. Serum markers of myocardial injury (cardiac troponin I [cTnI], cardiac troponin T [cTnT], and creatine kinase MB [CK-MB]) were measured and clinical outcomes were assessed. At the beginning of the study, 12 of 16 (75%) patients had increased serum enzyme-linked immunosorbent assay (ELISA) cTnT concentrations greater than 0.20 micrograms/L, eight (50%) had increased serum CK-MB greater than 5.0 micrograms/L, and three (19%) had an increased cTnI greater than 0.8 micrograms/L. Over the 1-year study period, the cardiac event rate (n = 4 with fatal myocardial infarction) was correlated to the patients who displayed the higher elevations of cTnT, CK-MB, and cTnI. In the remaining 12 patients studied at the end of 1 year, seven (58%) had increased ELISA cTnT levels and five (42%) had increased CK-MB levels; no patients had elevated cTnI levels. Reanalysis of ELISA cTnT values with a newly formulated Enzymun cTnT assay showed no significant differences. Our data suggest that whereas substantial increases in cardiac markers tended to have a poor prognostic outcome, there was a high incidence of increased cTnT and CK-MB concentrations without evidence of myocardial injury in chronic hemodialysis patients. The lack of absolute cardiospecificity of cTnT and CK-MB may prove cTnI to be the desired serum marker for the detection of myocardial injury in patients with chronic renal disease.

Clinical implementation of a rapid, automated assay for assessing fetal lung maturity

We retrospectively determined cutoff levels and implemented the use of the TDxFLx assay in assessing the likelihood or absence of respiratory distress syndrome or fetal lung maturity (FLM) in a high-risk obstetric setting when compared to the lecithin/sphingomyelin (L/S) ratio and disaturated lecithin (DSL) measurements. Using a mature TDxFLx cutoff value of > or = 50 mg/g and an immature cutoff value of < 20 mg/g, 88% of L/S ratio and DSL measurements could be eliminated without compromise to the patient. The > or = 50 mg/g TDxFLx cutoff value resulted in a sensitivity of 100% and specificity of 88%. We also recommend the use of the TDxFLx assay as a screening test in diabetic pregnancies. More timely patient care occurred when the rapid TDxFLx assay was implemented by the laboratory and used by clinicians.

Glycerol interference in serum lipase assay falsely indicates pancreas injury

The measurement of serum lipase activity has been shown to be a very sensitive and specific marker for the diagnosis of pancreatic injury. Two case reports are presented showing that glycerol ingested coincidentally in the formulation of several medications taken therapeutically and given in the emergency room causes a falsely elevated serum lipase activity when measured on the Kodak Ektachem 700 clinical analyzer (Eastman Kodak Co., Rochester, NY). The transient but falsely elevated serum lipase activity could potentially affect the differential diagnosis of patients by the admitting physician.

Financial impact of a rapid CK-MB-specific immunoassay on the diagnosis of myocardial infarction

The purpose of this study was twofold. First, we evaluated the financial impact of a rapid, monoclonal antibody-based CK-MB mass assay (Stratus, Dade Division, Baxter Laboratories, Miami, Fla) for the direct measurement of CK-MB in serum samples from 65 patients admitted to the coronary care unit with the possible diagnosis of acute myocardial infarction. Second, we evaluated retrospectively the Stratus assay and an activity assay (electrophoresis) for CK-MB in the following patient categories: acute myocardial infarction treated with and without thrombolytic therapy, angina, congestive heart failure, skeletal muscle trauma, and the acutely ill without acute myocardial infarction. The advantageous features of the Stratus mass assay were as follows. First, the laboratory was able to perform the assay more frequently because of the short assay time per specimen (less than 10 minutes) without additional personnel. This had a substantial impact on the clinician's ability to diagnose acute myocardial infarction and to move patients out of an intensive care unit at substantial financial savings to the patient, the hospital, or the third-party payer. Second, the Stratus assay was able to detect low levels of CK-MB (1 to 2 micrograms/L) in the presence of low total creatine kinase activity (less than 100 U/L). Third, the Stratus assay showed no interference due to very-high-total creatine kinase activities (greater than 100,000 U/L), CK-BB, macro-creatine kinase, and mitochondrial creatine kinase.

Factitiously high sodium activities on the Ektachem 400 owing to interferences by high gamma-globulin concentrations

Sera from patients with above-normal gamma-globulin concentrations give sodium values as much as 10% higher when measured in the Kodak Ektachem 400 analyzer than results obtained with the Beckman Astra-8 analyzer. Results obtained with the Astra were in agreement with flame photometry. A similar relative bias was observed for potassium measurement in the Ektachem. This discrepancy was corrected when we used a new generation of reference fluid provided by Kodak, which is currently available for general use.

Factitiously high sodium activities on the Ektachem 400 owing to interferences by high gamma-globulin concentrations

Sera from patients with above-normal gamma-globulin concentrations give sodium values as much as 10% higher when measured in the Kodak Ektachem 400 analyzer than results obtained with the Beckman Astra-8 analyzer. Results obtained with the Astra were in agreement with flame photometry. A similar relative bias was observed for potassium measurement in the Ektachem. This discrepancy was corrected when we used a new generation of reference fluid provided by Kodak, which is currently available for general use.