An Introduction to the Complete Blood Count for Clinical Chemists: Red Blood Cells

BACKGROUND

The most frequently ordered laboratory test worldwide is the complete blood count (CBC).

CONTENT

In this primer, the red blood cell test components of the CBC are introduced, followed by a discussion of the laboratory evaluation of anemia and polycythemia.

SUMMARY

As clinical chemists are increasingly tasked to direct laboratories outside of the traditional clinical chemistry sections such as hematology, expertise must be developed. This review article is a dedication to that effort.

Diabetes Study of Children of Diverse Ethnicity and Race: Study design

AIMS

Determining diabetes type in children has become increasingly difficult due to an overlap in typical characteristics between type 1 diabetes (T1D) and type 2 diabetes (T2D). The Diabetes Study in Children of Diverse Ethnicity and Race (DISCOVER) programme is a National Institutes of Health (NIH)-supported multicenter, prospective, observational study that enrols children and adolescents with non-secondary diabetes. The primary aim of the study was to develop improved models to differentiate between T1D and T2D in diverse youth.

MATERIALS AND METHODS

The proposed models will evaluate the utility of three existing T1D genetic risk scores in combination with data on islet autoantibodies and other parameters typically available at the time of diabetes onset. Low non-fasting serum C-peptide (<0.6 nmol/L) between 3 and 10 years after diabetes diagnosis will be considered a biomarker for T1D as it reflects the loss of insulin secretion ability. Participating centres are enrolling youth (<19 years old) either with established diabetes (duration 3-10 years) for a cross-sectional evaluation or with recent onset diabetes (duration 3 weeks-15 months) for the longitudinal observation with annual visits for 3 years. Cross-sectional data will be used to develop models. Longitudinal data will be used to externally validate the best-fitting model.

RESULTS

The results are expected to improve the ability to classify diabetes type in a large and growing subset of children who have an unclear form of diabetes at diagnosis.

CONCLUSIONS

Accurate and timely classification of diabetes type will help establish the correct clinical management early in the course of the disease.

Iron Biology - An Overview for Laboratorians

Iron serves a critical role in many metabolic processes, including oxygen delivery (e.g., hemoglobin) and oxygen utilization for the generation of ATP (e.g., cytochromes). Disorders of iron metabolism are best recognized and evaluated in the context of iron's absorption, transportation, monitoring, cellular uptake, and recycling. This review highlights these processes so that disorders of iron deficiency and iron excess can be better understood. Key players in iron metabolism will be highlighted, such as hepcidin, ferroportin, erythroferrone, transferrin, ferritin, HFE, and the transferrin receptors.

Dysfibrinogenemia: discrepant results following infusion of purified fibrinogen

Inherited dysfibrinogenemias are molecular disorders of fibrinogen that affect fibrin polymerization. The majority of cases are asymptomatic, but a significant proportion suffer from increased bleeding or thrombosis. We present two unrelated cases of dysfibrinogenemia, both of whom showed a characteristic discrepancy between fibrinogen activity and the immunologic fibrinogen. In one patient, the dysfibrinogenemia was confirmed by molecular analysis; in the other case, the diagnosis was presumptive based upon laboratory studies. Both patients underwent elective surgery. Both received a highly purified fibrinogen concentrate preoperatively and demonstrated a suboptimal laboratory response to the infusion. Three methods for determining fibrinogen concentration (Clauss fibrinogen, prothrombin-derived fibrinogen, and the viscoelastic functional fibrinogen) were utilized in the case of one patient, and these techniques showed discrepant results with the classic Clauss method giving the lowest concentration. Neither patient experienced excessive bleeding during surgery. Although these discrepancies have been previously described in untreated patients, their manifestation after infusion of purified fibrinogen is less well appreciated.

Islet Autoantibody Standardization Program: interlaboratory comparison of insulin autoantibody assay performance in 2018 and 2020 workshops

AIMS/HYPOTHESIS

The Islet Autoantibody Standardization Program (IASP) aims to improve the performance of immunoassays measuring autoantibodies in type 1 diabetes and the concordance of results across laboratories. IASP organises international workshops distributing anonymised serum samples to participating laboratories and centralises the collection and analysis of results. In this report, we describe the results of assays measuring IAA submitted to the IASP 2018 and 2020 workshops.

METHODS

The IASP distributed uniquely coded sera from individuals with new-onset type 1 diabetes, multiple islet autoantibody-positive individuals, and diabetes-free blood donors in both 2018 and 2020. Serial dilutions of the anti-insulin mouse monoclonal antibody HUI-018 were also included. Sensitivity, specificity, area under the receiver operating characteristic curve (ROC-AUC), partial ROC-AUC at 95% specificity (pAUC95) and concordance of qualitative/quantitative results were compared across assays.

RESULTS

Results from 45 IAA assays of seven different formats and from 37 IAA assays of six different formats were submitted to the IASP in 2018 and 2020, respectively. The median ROC-AUC was 0.736 (IQR 0.617-0.803) and 0.790 (IQR 0.730-0.836), while the median pAUC95 was 0.016 (IQR 0.004-0.021) and 0.023 (IQR 0.014-0.026) in the 2018 and 2020 workshops, respectively. Assays largely differed in AUC (IASP 2018 range 0.232-0.874; IASP 2020 range 0.379-0.924) and pAUC95 (IASP 2018 and IASP 2020 range 0-0.032).

CONCLUSIONS/INTERPRETATION

Assay formats submitted to this study showed heterogeneous performance. Despite the high variability across laboratories, the in-house radiobinding assay (RBA) remains the gold standard for IAA measurement. However, novel non-radioactive IAA immunoassays showed a good performance and, if further improved, might be considered valid alternatives to RBAs.

Practical Clinical Applications of Islet Autoantibody Testing in Type 1 Diabetes

BACKGROUND

The distinction between type 1 diabetes (T1D) and type 2 diabetes (T2D) is extremely important for the choice of therapy, body weight and dietary management, screening for coexistent autoimmune diseases and comorbidities, anticipated prognosis, and risk assessment in relatives. Not uncommonly, the presentation of the patient may not allow an unambiguous discrimination between T1D and T2D. To help resolve this challenge, the detection of islet autoantibodies can support the diagnosis of T1D.

CONTENT

The presence of islet autoantibodies in a person with diabetes indicates an autoimmune etiology therefore establishing the diagnosis of T1D. Presently 5 islet autoantibodies are available for routine clinical use: islet cell cytoplasmic autoantibodies (ICA), insulin autoantibodies (IAA), glutamic acid decarboxylase autoantibodies (GADA), insulinoma associated-2 autoantibodies (IA-2A), and zinc transporter-8 autoantibodies (ZnT8A). There are caveats to the selection of which islet autoantibodies should be measured. Islet autoantibodies can also predict the development of T1D. Therefore, once safe and effective therapies are available to prevent T1D, islet autoantibody testing is expected to become a routine part of medical practice. A very rare cause of autoimmune diabetes is the type B insulin resistance syndrome resulting from antagonistic autoantibodies to the insulin receptor. Rarely hypoglycemia can result from agonistic insulin receptor autoantibodies, or high-titer IAA causing the autoimmune insulin syndrome (i.e., Hirata disease).

SUMMARY

In summary, autoimmune causes of dysglycemia are increasing in clinical importance requiring the scrutiny of laboratorians. The determination of islet autoantibodies can greatly aid in the diagnosis and the prediction of T1D.

The Interaction between Hb A1C and Selected Genetic Factors in the African American Population in the USA

BACKGROUND

The global prevalence of diabetes mellitus has been growing in recent decades and the complications of longstanding type 2 diabetes continue to place a burden on healthcare systems. The hemoglobin A1c (Hb A1c) content of the blood is used to assess an individual's degree of glycemic control averaged over 2 to 3 months. In the USA, diabetes is the seventh leading cause of death. Black, indigenous, people of color (BIPOC) are disproportionately affected by diabetes compared to non-Hispanic whites. There are many reports of interaction of Hb A1c and hematologic conditions that have a high prevalence in the Black population; some of these effects are contradictory and not easily explained. This review attempts to document and categorize these apparently disparate effects and to assess any clinical impact.

METHODS

Hb A1C can be determined by a variety of techniques including cation-exchange chromatography, electrophoresis, immunoassays, and affinity chromatography. The amount of Hb A1c present in a patient specimen depends not only on blood glucose but is strongly influenced by erythrocyte survival and by structural variations in the globin chains. Sickling hemoglobinopathies are well-represented in the USA in African Americans and the effects of these hemoglobin disorders as well as G6PD deficiency is examined.

CONCLUSION

Hb A1c measurement should always be performed with a cautious approach. The laboratory scientist should be aware of possible pitfalls in unquestioningly determining Hb A1c without a consideration of hematologic factors, both inherited and acquired. This presents a challenge as often times, the laboratory is not aware of the patient's race.

Clotting factors: Clinical biochemistry and their roles as plasma enzymes

The purpose of this review is to describe structure and function of the multiple proteins of the coagulation system and their subcomponent domains. Coagulation is the process by which flowing liquid blood plasma is converted to a soft, viscous gel entrapping the cellular components of blood including red cells and platelets and thereby preventing extravasation of blood. This process is triggered by the minimal proteolysis of plasma fibrinogen. This transforms the latter to sticky fibrin monomers which polymerize into a network. The proteolysis of fibrinogen is a function of the trypsin-like enzyme termed thrombin. Thrombin in turn is activated by a cascade of trypsin-like enzymes that we term coagulation factors. In this review we examine the mechanics of the coagulation cascade with a view to the structure-function relationships of the proteins. We also note that two of the factors have no trypsin like protease domain but are essential cofactors or catalysts for the proteases. This review does not discuss the major role of platelets except to highlight their membrane function with respect to the factors. Coagulation testing is a major part of routine diagnostic clinical pathology. Testing is performed on specimens from individuals either with bleeding or with thrombotic disorders and those on anticoagulant medications. We examine the basic in-vitro laboratory coagulation tests and review the literature comparing the in vitro and in vivo processes. In vitro clinical testing typically utilizes plasma specimens and non-physiological or supraphysiological activators. Because the review focuses on coagulation factor structure, a brief overview of the evolutionary origins of the coagulation system is included.

Islet Autoantibody Standardization Program 2018 Workshop: Interlaboratory Comparison of Glutamic Acid Decarboxylase Autoantibody Assay Performance

BACKGROUND

The Islet Autoantibody Standardization Program (IASP) aims to improve the performance of immunoassays measuring type 1 diabetes (T1D)-associated autoantibodies and the concordance of results among laboratories. IASP organizes international interlaboratory assay comparison studies in which blinded serum samples are distributed to participating laboratories, followed by centralized collection and analysis of results, providing participants with an unbiased comparative assessment. In this report, we describe the results of glutamic acid decarboxylase autoantibody (GADA) assays presented in the IASP 2018 workshop.

METHODS

In May 2018, IASP distributed to participants uniquely coded sera from 43 new-onset T1D patients, 7 multiple autoantibody-positive nondiabetic individuals, and 90 blood donors. Results were analyzed for the following metrics: sensitivity, specificity, accuracy, area under the ROC curve (ROC-AUC), partial ROC-AUC at 95% specificity (pAUC95), and concordance of qualitative and quantitative results.

RESULTS

Thirty-seven laboratories submitted results from a total of 48 different GADA assays adopting 9 different formats. The median ROC-AUC and pAUC95 of all assays were 0.87 [interquartile range (IQR), 0.83-0.89] and 0.036 (IQR, 0.032-0.039), respectively. Large differences in pAUC95 (range, 0.001-0.0411) were observed across assays. Of formats widely adopted, bridge ELISAs showed the best median pAUC95 (0.039; range, 0.036-0.041).

CONCLUSIONS

Several novel assay formats submitted to this study showed heterogeneous performance. In 2018, the majority of the best performing GADA immunoassays consisted of novel or established nonradioactive tests that proved on a par or superior to the radiobinding assay, the previous gold standard assay format for GADA measurement.

Diabetes Technology-Continuous Subcutaneous Insulin Infusion Therapy and Continuous Glucose Monitoring in Adults: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

To formulate clinical practice guidelines for the use of continuous glucose monitoring and continuous subcutaneous insulin infusion in adults with diabetes.

PARTICIPANTS

The participants include an Endocrine Society-appointed Task Force of seven experts, a methodologist, and a medical writer. The American Association for Clinical Chemistry, the American Association of Diabetes Educators, and the European Society of Endocrinology co-sponsored this guideline.

EVIDENCE

The Task Force developed this evidence-based guideline using the Grading of Recommendations, Assessment, Development, and Evaluation system to describe the strength of recommendations and the quality of evidence. The Task Force commissioned one systematic review and used the best available evidence from other published systematic reviews and individual studies.

CONSENSUS PROCESS

One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of the Endocrine Society, the American Association for Clinical Chemistry, the American Association of Diabetes Educators, and the European Society of Endocrinology reviewed and commented on preliminary drafts of these guidelines.

CONCLUSIONS

Continuous subcutaneous insulin infusion and continuous glucose monitoring have an important role in the treatment of diabetes. Data from randomized controlled trials are limited on the use of medical devices, but existing studies support the use of diabetes technology for a wide variety of indications. This guideline presents a review of the literature and practice recommendations for appropriate device use.

Detection of Antibodies Directed to the N-Terminal Region of GAD Is Dependent on Assay Format and Contributes to Differences in the Specificity of GAD Autoantibody Assays for Type 1 Diabetes

GAD autoantibodies (GADAs) are sensitive markers of islet autoimmunity and type 1 diabetes. They form the basis of robust prediction models and are widely used for the recruitment of subjects at high risk of type 1 diabetes to prevention trials. However, GADAs are also found in many individuals at low risk of diabetes progression. To identify the sources of diabetes-irrelevant GADA reactivity, we analyzed data from the 2009 and 2010 Diabetes Autoantibody Standardization Program GADA workshop and found that binding of healthy control sera varied according to assay type. The characterization of control sera found positive by radiobinding assay (RBA), but negative by ELISA, showed that many of these sera reacted to epitopes in the N-terminal region of the molecule. This finding prompted development of an N-terminally truncated GAD65 radiolabel, (35)S-GAD65(96-585), which improved the performance of most GADA RBAs participating in an Islet Autoantibody Standardization Program GADA substudy. These detailed workshop comparisons have identified a source of disease-irrelevant signals in GADA RBAs and suggest that N-terminally truncated GAD labels will enable more specific measurement of GADAs in type 1 diabetes.

The molecular biology of human iron metabolism

Iron is one of the most important nonorganic substances that make life possible. Iron plays major roles in oxygen transport (eg, hemoglobin; -67% of total body iron [TBI]), short-term oxygen storage (eg, myoglobin; -3.5% of TBI), and energy generation (eg, cytochromes; -3% of TBI). Iron also serves vital roles in various nonheme-containing enzymes (-2% of TBI). Figure 1 lists heme-containing and nonheme iron-containing proteins. TBI is controlled by the rate of iron absorption; there are no physiologic mechanisms to excrete excess iron. Iron deficiency has many adverse consequences, including anemia, and in children, behavioral and learning disorders. Iron excess is toxic to the body, harming the heart, liver, skin, pancreatic islet beta cells, bones, joints, and pituitary gland. Maintaining proper iron balance is essential for maintaining homeostasis and health. TBI in adults normally ranges between 3.5 and 5.0 g. A total of 75% of TBI is functional, and 25% is stored within cells as ferritin or hemosiderin. Ferritin contains 24 subunits of light chains (L chains; 19.7 kDa) and heavy chains (H chains; 21.1 kDa). The L chains are encoded on chromosome 19q13.33 and are 175 amino acids long. The H chains are encoded on chromosome 11q1 and are 183 amino acids long. Each ferritin molecule can contain as many as approximately 4500 ferric ions. Because the major role of iron is in hemoglobin synthesis, this review will focus on iron, iron transport, and hematopoiesis.

Intrathyroidal parathyroid carcinoma: report of an unusual case and review of the literature

Intrathyroidal parathyroid carcinoma is an exceedingly rare cause of primary hyperparathyroidism. A 51-year-old African American female presented with goiter, hyperparathyroidism, and symptomatic hypercalcemia. Sestamibi scan revealed diffuse activity within an enlarged thyroid gland with uptake in the right thyroid lobe suggestive of hyperfunctioning parathyroid tissue. The patient underwent thyroidectomy and parathyroidectomy. At exploration, a 2.0 cm nodule in the usual location of the right inferior parathyroid was sent for intraoperative frozen consultation, which revealed only ectopic thyroid tissue. No parathyroid glands were identified grossly on the external aspect of the thyroid. Interestingly, postoperative parathyroid hormone levels normalized after removal of the thyroid gland. Examination of the thyroidectomy specimen revealed a 1.4 cm parathyroid nodule located within the parenchyma of the right superior thyroid, with capsular and vascular invasion and local infiltration into surrounding thyroid tissue. We present only the eighth reported case of intrathyroidal parathyroid carcinoma and review the literature.

Novel detection of pancreatic and duodenal homeobox 1 autoantibodies (PAA) in human sera using luciferase immunoprecipitation systems (LIPS) assay

We have previously identified pancreatic and duodenal homeobox 1 (Pdx1) autoantibodies (PAA) in sera from both non-obese diabetic (NOD) mice and human type 1 diabetic (T1D) patients. A suitable non-radioactive, sensitive and specific assay is needed for large-scale testing to determine the clinical utility of PAA. Here we reported a liquid-phase luciferase immunoprecipitation system (LIPS) assay by generating a renilla luciferase (Rluc)-Pdx1 fusion protein as a sensitive non-radioactive antigen from mammalian cells combined with immunoprecipitation to detect PAA in human sera. Sera from healthy donors and the University of Florida Pathology Laboratories, Endocrine Autoantibody Laboratory were used to validate the LIPS assay for PAA. Antigenic specificity to Pdx1 was confirmed by using a Rluc-only control compared to Rluc-Pdx1 fusion antigen and by competition assays using purified recombinant Pdx1 protein. We then used the LIPS assay to assess the prevalence of triple autoantibodies (GADA, IA-2A, and IA-2βA), and PAA in non-T1D control sera, recent onset (RO)-T1D sera (mean duration of T1D = 9.5 weeks), and long standing (LS)-T1D sera. Compared to clinical radioimmunoprecipitation assays (RIPA), the LIPS assay showed comparable sensitivity and specificity for detection of GADA and IA-2A. PAA were detectable in human serum samples and higher in triple-positive T1D autoantibodies (21% PAA positive in triple positive sera and 4% PAA positive in triple negative sera). Interestingly, PAA were found to be highest in the non-T1D population, suggesting that PAA might have a clinical utility in screening high-risk population susceptible for developing T1D. In conclusion, we have developed a liquid-phase, non-radioactive, sensitive and specific LIPS assay to detect PAA in human sera, providing a useful tool for evaluating the clinical relevance of PAA.

Continuing routine cardiac surveillance in long-term use of pegylated liposomal doxorubicin: is it necessary?

OBJECTIVE

The objective of this study was to determine the cardiac safety of high cumulative doses of pegylated liposomal doxorubicin (PLD) in patients with gynecologic malignancies and the need for routine evaluation of left ventricular ejection fraction (LVEF).

METHODS

Data were collected for all patients treated with PLD with at least one evaluation of LVEF with either Multi-Gated Acquisition (MUGA) scan or echocardiogram from January 2006 to May 2012. Evaluation of LVEF was used to detect PLD-related cardiac toxicity (defined as a decline in LVEF of greater than 10% compared to baseline measurements).

RESULTS

A total of 141 patients were included. Twenty-two patients were treated with a cumulative dose of 500 mg/m(2) or more, and five patients with 1000 mg/m(2) or more. Ten patients (7%) had a reduction in LVEF of greater than 10%, 38 had no significant change or increase in LVEF throughout the duration of treatment, and 93 did not require a follow-up evaluation of LVEF. The LVEFs of two patients dropped below 50% at cumulative doses of 1110 mg/m(2) and 1670 mg/m(2); one began with a baseline of 52%.

CONCLUSIONS

Only one patient had a clinically significant decrease in LVEF at a cumulative dose of 1670 mg/m(2), suggesting that PLD does not carry a significant risk of cardiotoxicity, as evidenced by the stability of LVEF even after treatment with large cumulative doses. Routine surveillance of LVEF does not seem to be necessary or cost effective in the absence of other risk factors.

Risk of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) after adjuvant chemotherapy (CT) for early breast cancer (BC) in the community setting

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Background: AML and MDS complicate adjuvant CT in BC. Incidence Rates of MDS/AML with pegfilgrastim (PGCSF) use and newer adjuvant regimens in large patient (pt) populations are not widely characterized. Methods: We queried the iKnowMed electronic health record from a large network of community oncology practices for pts diagnosed with stage I-III BC from 2007-2010 with at least 5 visits and follow up (f/u) through 2/2012 for our retrospective study. We stratified pts by adjuvant CT utilization (yes/no), regimen type, PGCSF use, age, and characterized the incidence of MDS/AML captured as a secondary diagnosis. Fisher’s exact test and student t-test were used for categorical and continuous variables, respectively; Cox proportional hazard model was used to estimate hazard ratios (HR) for risk factors associated with AML/MDS development. Results: We identified 20,900 pts with median f/u of 2.8 years (yrs) (1.2-5.2 yrs). 11,295 pts (54%) received CT, 41% of whom received anthracyclines (A); 9,605 (46%) did not receive CT. Median age of diagnosis in the CT and non-CT arms was 54 and 64 yrs, respectively (p < 0.01). Among the CT-treated group, 12 pts or 0.11% (95% CI, 0.06-0.19) developed AML/MDS with median time to onset of 1.8 yrs and median f/u of 2.7 yrs. Of these 12 pts, 8 received A and 11 PGCSF. In the non-CT group, 18 pts or 0.19% (95% CI, 0.11-0.30) developed AML/MDS with median time to onset of 2.2 yrs and median f/u of 3 yrs (p=NS). Multivariate analysis of pts who received CT revealed pts ≥70 vs. <70 yrs and those that received A-containing vs. alternate regimens were more likely to develop AML/MDS. Conclusions: Adjuvant CT did not increase risk of AML/MDS compared with those that did not receive CT. However, our findings confirm that increased age and A-containing CT regimens are associated with increased risk. The low event rate in our study population may be due to short f/u, younger age in the CT treated arm, and high utilization of non-A CT. Association with PGCSF warrants further evaluation. [Table: see text]

Robotic surgical staging for obese patients with endometrial cancer

OBJECTIVE

To compare surgical outcomes for robotic vs laparotomy staging in obese endometrial cancer patients.

STUDY DESIGN

This was a retrospective cohort study of patients with body mass index ≥30 kg/m(2) staged in a community gynecologic oncology practice. Patients undergoing robotic staging were compared with historic laparotomy controls.

RESULTS

One hundred twenty-nine patients underwent robotic staging, compared with 110 laparotomy patients. The robotic cohort had fewer abdominal wound complications (13.9% vs 32.7%, P < .001), but more vaginal cuff complications (4.7% vs 0%, P = .032). Blood loss was lower in the robotic group (P < .001), as was length of stay (P < .001). Surgical times were longer in the robotic group (P < .001). There was no difference in terms of percentage of patients undergoing pelvic or paraaortic lymph node dissection.

CONCLUSION

Robotic staging for endometrial cancer is feasible in obese women, with fewer abdominal wound complications, but more vaginal cuff complications.

Surgically managed stage I endometrial cancer in a low-volume center: outcomes and complications in a military residency program

OBJECTIVE

The purpose of this study was to compare operative outcomes and complications for patients with endometrial cancer who underwent staging by laparoscopy vs laparotomy in a low-volume facility.

STUDY DESIGN

Research was conducted with a retrospective cohort of surgical patients with clinical stage I endometrial cancer from 2004-2009.

RESULTS

Eighty-six demographically similar patients (50 laparotomy and 36 laparoscopy) were identified. Laparoscopy had less estimated blood loss (339 vs 558 mL; P = .013) and lower rates of transfusion (5.6% vs 24%; P = .02). Laparoscopy was longer (281 vs 202 minutes; P < .0005) but required a shorter hospital stay (2.2 vs 5.5 days; P < .0005). Laparoscopy patients had fewer overall complications (16.7% vs 32%; P = .11). No differences in final surgical stage or lymph node yields between the groups were present.

CONCLUSION

Although a longer procedure, laparoscopy had fewer complications and shorter hospital stays. Prolonged operative time, compared with published experience, is potentially the result of unique factors in our center.

Comparison of two insulin assays for first-phase insulin release in type 1 diabetes prediction and prevention studies

BACKGROUND

Detection of below-threshold first-phase insulin release or FPIR (1+3 minute insulin concentrations during an intravenous glucose tolerance test [IVGTT]) is important in type 1 diabetes prediction and prevention studies including the TrialNet Oral Insulin Prevention Trial. We assessed whether an insulin immunoenzymometric assay (IEMA) could replace the less practical but current standard of a radioimmunoassay (RIA) for FPIR.

METHODS

One hundred thirty-three islet autoantibody positive relatives of persons with type 1 diabetes underwent 161 IVGTTs. Insulin concentrations were measured by both assays in 1056 paired samples. A rule classifying FPIR (below-threshold, above-threshold, uncertain) by the IEMA was derived and validated against FPIR by the RIA.

RESULTS

The insulin IEMA-based rule accurately classified below- and above-threshold FPIRs by the RIA in 110/161 (68%) IVGTTs, but was uncertain in 51/161 (32%) tests for which FPIR by RIA is needed. An uncertain FPIR by the IEMA was more likely among below-threshold vs above-threshold FPIRs by the RIA (64% [30/47] vs. 18% [21/114], respectively; p<0.05).

CONCLUSIONS

An insulin IEMA for FPIR in subjects at risk for type 1 diabetes accurately determined below- and above-threshold FPIRs in 2/3 of tests relative to the current standard of the insulin RIA, but could not reliably classify the remaining FPIRs. TrialNet is limiting the insulin RIA for FPIR to the latter given the practical advantages of the more specific IEMA.

Autoimmune markers in diabetes

BACKGROUND

Type 1 diabetes (T1DM) results from cell-mediated autoimmune destruction of the β cells of the islets of Langerhans. Autoantibodies directed against the islets are useful clinical tools that allow the recognition and confirmation of β-cell autoimmunity.

CONTENT

In this review we define the term "islet autoantibody," describe the pathogenesis of autoantibody generation, and explain the uses of islet autoantibodies in clinical medicine and in research studies that concern the interruption or prevention of T1DM. We also discuss the biology of islet autoantibodies and their rates of appearance at the time of onset of T1DM and their appearance before the development of T1DM.

SUMMARY

The presence of islet autoantibodies in persons with diabetes confirms an autoimmune etiology. In nondiabetic individuals, islet autoantibodies are strong predictors of the later development of T1DM.

Primary intussusception in pregnancy: a case report

BACKGROUND

Intussusception is a rare cause of bowel obstruction in adults, typically associated with malignancy, granuloma formation, a foreign body or an anatomic defect.

CASE

A 21-year-old, primiparous woman presented at 33 5/7 weeks' gestation with vague abdominal symptoms consistent with acute viral gastroenteritis. She did not improve with conservative measures. A presumptive diagnosis of severe preeclampsia was made based on elevated blood pressure, abnormal liver function tests and epigastric pain. Labor was induced 34 5/7 weeks' gestation. The patient did not improve after an uncomplicated vaginal delivery. Abdominal radiographs and computed tomography were consistent with intussusception. Surgical findings were consistent with the radiologic findings. The patient underwent a right hemicolectomy with stapled anastomosis. No pathologic or anatomically anomalous lead point was identified intraoperatively or on final pathology.

CONCLUSION

Intussusception is a rare finding in the peripartum period, often presenting with vague abdominal symptoms and mistaken for benign obstetric and nonobstetric diseases. This case is only the second one of adult perinatal intussusception without an anatomic or pathologic lead point.

Tumor residual after surgical cytoreduction in prediction of clinical outcome in stage IV epithelial ovarian cancer: a Gynecologic Oncology Group Study

PURPOSE

To identify factors predictive of poor prognosis in a similarly treated population of women with stage IV epithelial ovarian cancer (EOC).

PATIENTS AND METHODS

A retrospective review of 360 patients with International Federation of Gynecology and Obstetrics stage IV EOC who underwent primary surgery followed by six cycles of intravenous platinum/paclitaxel was performed. A proportional hazards model was used to assess the association of potential prognostic factors with progression-free survival (PFS) and overall survival (OS).

RESULTS

The median PFS and OS for this group of stage IV ovarian cancer patients was 12 and 29 months, respectively. Multivariate regression analysis revealed that histology, malignant pleural effusion, intraparenchymal liver metastasis, and residual tumor size were significant prognostic variables. Whereas patients with microscopic residual disease had the best outcome, patients with 0.1 to 1.0 cm residual disease and patients with 1.1 to 5.0 cm residual disease had similar PFS and OS. Patients with a residual size more than 5 cm had a diminished PFS and OS when compared with all other groups. Median OS for microscopic, 0.1 to 5.0 cm, and more than 5.0 cm residual disease was 64, 30, and 19 months, respectively.

CONCLUSION

Patients with more than 5 cm residual disease have the shortest PFS and OS, whereas patients with 0.1 to 1.0 and 1.1 to 5.0 cm have similar outcome. These findings suggest that ultraradical cytoreductive procedures might be targeted for selected patients in whom microscopic residual disease is achievable. Patients with less than 5.0 cm of disease initially and significant disease and/or comorbidities precluding microscopic cytoreduction may be considered for alternative therapeutic options other than primary cytoreduction.

Prognostic factors for stage III epithelial ovarian cancer: a Gynecologic Oncology Group Study

PURPOSE

Conflicting results on prognostic factors for advanced epithelial ovarian cancer (EOC) have been reported because of small sample size and heterogeneity of study population. The purpose of this study was to identify factors predictive of poor prognosis in a similarly treated population of women with advanced EOC.

PATIENTS AND METHODS

A retrospective review of demographic, pathologic, treatment, and outcome data from 1,895 patients with International Federation of Gynecology and Obstetrics stage III EOC who had undergone primary surgery followed by six cycles of intravenous platinum/paclitaxel was conducted. A proportional hazards model was used to assess the association of prognostic factors with progression-free survival (PFS) and overall survival (OS).

RESULTS

Increasing age was associated with increased risks for disease progression (HR = 1.06; 95% CI, 1.02 to 1.11 for an increase every 10 years) and death (HR = 1.12; 95% CI, 1.06 to 1.18). Mucinous or clear-cell histology was associated with a worse PFS and OS compared with serous carcinomas. Patients with performance status (PS) 1 or 2 were at an increased risk for recurrence compared with PS 0 (HR = 1.12; 95% CI, 1.01 to 1.24). Compared with patients with microscopic residual disease, patients with 0.1 to 1.0 cm and > 1.0 cm residual disease had an increased risk of recurrence (HR = 1.96; 95% CI, 1.70 to 2.26; and HR = 2.36; 95% CI, 2.04 to 2.73, respectively) and death (HR = 2.11; 95% CI, 1.78 to 2.49; P < .001; and HR = 2.47; 95% CI, 2.09 to 2.92, respectively).

CONCLUSION

Age, PS, tumor histology, and residual tumor volume were independent predictors of prognosis in patients with stage III EOC. These data can be used to identify patients with poor prognosis and to design future tailored randomized clinical trials.

A phase I trial of oxaliplatin and topotecan in recurrent ovarian carcinoma

OBJECTIVE

Oxaliplatin and topotecan have demonstrated activity as single agents against recurrent platinum-sensitive and -resistant ovarian cancer, as well as synergy in vitro. This was a dose-finding study of combination therapy with weekly topotecan and alternating-week oxaliplatin in patients with recurrent epithelial ovarian cancer.

METHODS

Eligible patients had a diagnosis of recurrent ovarian or primary peritoneal carcinoma, a performance status of 0-2, and normal bone marrow, renal, and hepatic function. On days 1 and 15 of a 28-day cycle, patients received a fixed dose of oxaliplatin (85 mg/m2) via intravenous infusion. On days 1, 8, and 15, patients received an escalating dose of intravenous topotecan (2.0-4.0 mg/m2). Five dose levels were planned with a minimum cohort of 3 patients at each level.

RESULTS

Thirteen patients were enrolled and received a total of 50 cycles of chemotherapy. The maximum tolerated dose was 85 mg/m2 of oxaliplatin and 3.0 mg/m2 of topotecan, and grade 3 neutropenia was the dose-limiting toxicity. Four of nine (44%) evaluable patients had stable disease or a partial response to the drug combination as assessed by cancer antigen-125 levels.

CONCLUSIONS

A 28-day schedule of oxaliplatin and topotecan is safe and well tolerated. Because of the in vitro synergy observed between topoisomerase I inhibitors and platinum derivatives and the tolerability reported in the current study, this regimen warrants further investigation.

Carcinomas of the female genital tract occurring after pelvic irradiation: a report of 15 cases

The concept of postradiation sarcoma is widely appreciated, however carcinomas arising in previously irradiated fields, the putative "postradiation carcinoma," are less well understood. Fifteen patients who developed gynecological malignancies after pelvic radiation therapy were studied. Five of these patients had HPV-related tumors both pre- and post- irradiation. Ten were irradiated for cervical cancer, one for endometrial carcinoma, one for vulvar carcinoma, one for colon cancer and 2 for benign conditions. The mean and median latent periods from the initiation of radiation therapy to the development of the second malignancy were 22.8 and 19 years, respectively (22.4 and 19.5 years, respectively, for non-HPV-related cancers; 24 and 18 years for HPV-related cancers). The "postradiation" malignancies included 2 ovarian carcinomas, 5 vaginal carcinomas (3 invasive, 2 in situ), 4 endometrial carcinomas, one cervical carcinoma, one vulvar carcinoma, one distal urethral carcinoma, and one pelvic carcinoma of unclear primary site. Gynecological carcinomas may occur many years after pelvic irradiation. Although the evidence for a causative role is circumstantial, these tumors appear to have a similar latent period as postradiation sarcomas.

Analytic bias of thyroid function tests: analysis of a College of American Pathologists fresh frozen serum pool by 3900 clinical laboratories

CONTEXT

In proficiency testing surveys, there are differences in the values reported by users of various analytic methods. Two contributors to this variation are calibrator bias and matrix effects of proficiency testing materials.

OBJECTIVES

(1) To quantify the biases of the analytic methods used to measure thyroid-stimulating hormone, thyroxine, triiodothyronine, free thyroxine, and free triiodothyronine levels; (2) to determine if these biases are within allowable limits; and (3) to ascertain if proficiency testing materials correctly identify these biases.

DESIGN

A fresh frozen serum specimen was mailed as part of the 2003 College of American Pathologists Ligand and Chemistry surveys. The means and SDs for each analytic method were determined for this sample as well as for a proficiency testing sample from both surveys. In the fresh frozen serum sample, target values for thyroxine and triiodothyronine were determined by isotope dilution/liquid chromatography/tandem mass spectrometry. All other target values in the study were the median of the means obtained for the various analytic methods.

MAIN OUTCOME MEASURES

Calibration biases were calculated by comparing the mean of each analytic method with the appropriate target values. These biases were evaluated against limits based on intra- and interindividual biological variation. Matrix effects of proficiency testing materials were assessed by comparing the rank of highest to lowest analytic method means (Spearman rank test) for each analyte.

PARTICIPANTS

Approximately 3900 clinical laboratories were enrolled in the College of American Pathologists Chemistry and Ligand surveys.

RESULTS

The number of methods in the Ligand Survey that failed to meet the goals for bias was 7 of 17 for thyroid-stimulating hormone and 11 of 13 for free thyroxine. The failure rates were 12 of 16 methods for thyroxine, 8 of 11 for triiodothyronine, and 9 of 11 for free triiodothyronine. The means of the analytic method for the proficiency testing material correlated significantly (P < .05) only with the fresh frozen serum means for thyroxine and thyroid-stimulating hormone in the Chemistry Survey and free triiodothyronine in the Ligand Survey.

CONCLUSIONS

A majority of the methods used in thyroid function testing have biases that limit their clinical utility. Traditional proficiency testing materials do not adequately reflect these biases.