Assessment of the Precision and Functional Sensitivity of Two Thyroglobulin Assays: Comparison of the Second-Generation Roche Electrochemiluminescent Immunoassay and BRAHAMS Radioimmunoassay

BACKGROUND: Thyroglobulin (Tg) is the primary biochemical marker used to monitor patients with differentiated thyroid cancer (DTC) for residual or recurrent disease after total thyroidectomy, as only normal or well-differentiated malignant thyroid cells produce Tg. Here, we evaluated the precision and functional sensitivity (FS) of a recently developed highly sensitive Tg (hsTg) electrochemiluminescent immunoassay (ECLIA) and compared it to that of the radioimmunoassay (RIA) method using pooled human serum with low levels of Tg. METHODS: For the ECLIA method, the Elecsys Tg II kit (Roche Diagnostics, Germany) was used with an E170 analyzer (Roche Diagnostics). For the RIA method, the Tg-plus-RIA kit (BRAHAMS, Germany) was used with a Cobra Quantum gamma counter (Packard Instrument Company, USA). The precision and limit of detection (LOD) were determined according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. FS was determined using a modification of the CLSI guideline. RESULTS: The total precision of the hsTg ECLIA and RIA methods was 9.6% and 48.2%, respectively. The manufacturer-reported LOD was verified by the hsTg ECLIA (0.04 ng/mL), but not by the RIA method (>0.08 ng/mL). The hsTg ECLIA showed better FS (0.04 ng/mL at a coefficient of variation [CV] of 10%) than the RIA method (0.37 ng/mL at a CV of 20%). CONCLUSIONS: Thus, the hsTg ECLIA performed better than the RIA method in terms of FS, which is extremely important for the early detection of residual or recurrent disease in DTC patients after total thyroidectomy. The excellent performance of the hsTg ECLIA could allow for clinical Tg measurement without thyroid-stimulating hormone stimulation, in contrast to the insufficient performance of the RIA method.

A Case of Therapy-related Myeloid Neoplasm after Successful Treatment of Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) is considered as a curative disease after combined chemotherapy based on all-trans retinoic acid (ATRA) and anthracycline. However, as long-term survivors continue to increase, reports on sporadic cases of therapy-related myeloid neoplasm (t-MN) after successful APL treatment are also increasing. Recently, we have experienced one patient who developed t-MN 7 yr after APL diagnosis. Even though he had not been exposed to alkylating agents at all, he showed alkylating agents-associated features such as long latency period (>5 yr), first presentation as myelodysplatic phase (multilineage dysplasia with increased blasts), and complex karyotype including monosomy 5 and 7. He received only supportive care and expired 3 months after the diagnosis of t-MN (6 months of survival after the onset of cytopenias). t-MN after complete remission of APL is a rare but fatal complication, and patients with complex karyotypes show ominous prognosis in particular. For the early diagnosis of t-MN, long-term and close monitoring of the patient is needed. One should suspect this late complication whenever any unknown cytopenia develops, and should perform bone marrow biopsy and cytogenetic analysis.

Comparison of Rapid Antigen Test and Real-Time Reverse Transcriptase PCR for Diagnosing Novel Swine Influenza A (H1N1) / 대한임상미생물학회지

BACKGROUND: Novel swine influenza (H1N1) was first identified in Mexico in April 2009. Because of its high infectivity and worldwide distribution, a rapid and efficient screening test is necessary. Here we evaluated the usefulness of a rapid antigen test currently in use, compared to real-time RT-PCR (rRT-PCR) as a screening test for detection of novel swine influenza (H1N1). METHODS: A total of 1,228 patients who visited Hallym University Kangdong Sacred Heart Hospital with influenza-like illness between 14 August 2009 and 30 September 2009, and were tested by both rapid antigen and rRT-PCR tests, were enrolled in this study. RESULTS: Sensitivity, specificity, predictive value of a positive test, and predictive value of a negative test for the rapid antigen test were 30.5%, 99.2%, 86.4% and 90.1%, respectively. Fifty-one (4.2%) patients were positive for both rapid antigen test and rRT-PCR, and 1,053 (85.7%) were negative for both rapid antigen test and rRT-PCR. A total of 124 (10.1%) patients showed a discrepancy between the two tests. Among them, 116 (9.4%) were only positive for rRT-PCR and 8 (0.7%) were only positive for the rapid antigen test. The latter 8 patients all showed negative H1/M2 results in rRT-PCR. There were significant differences in detection rates of the rapid antigen test between different H1 Ct (threshold cycle) interval groups and for different age groups (P<0.05). CONCLUSION: Although the rapid antigen test is easy to perform and provides fast results, its limits as a screening test for detection of novel swine influenza (H1N1) due to its low sensitivity compared to rRT-PCR need to be considered in practical situations.

Evaluation of the Tosoh HLC-723 G8 HbA1c Autoanalyzer / 임상검사와정도관리

BACKGROUND: We evaluated overall performance and analysis time of newly developed HLC-723 G8 (Tosoh corp., Tokyo, Japan) HbA1c autoanalyzerwhich utilizes cation-exchange HPLC method. METHODS: Linearity, precision, correlation with Variant II Turbo (Bio-Rad Laboratories, Hercules, CA, USA), analysis time, labile HbA1c (L-A1c) separation ability and stability of refrigerated sample at 4degrees C were evaluated. RESULTS: HLC-723 G8 showed good linearity between HbA1c 4.9-12.0% range (R2=0.9995). Within-run and total imprecision (CVs) were less than 1.0%. Correlation with Variant II Turbo and L-A1c separation ability were excellent. Analysis time per sample took 1.0 min. Stability of refrigerated sample at 4degrees C for at least 21 days was good. CONCLUSIONS: HLC-723 G8 showed good analytical performance and its rapid analysis time enables us to support outpatient diagnosis of diabetic patients efficiently.