Citations

Abstract Introduction: Transsphenoidal surgery is recommended as first line therapy in the vast majority of patients with acromegaly. Successful surgical intervention is determined by normalization of insulin like-growth factor (IGF) - 1 and adequate suppression of growth hormone (GH) during glucose GH suppression test or random GH levels <1.0 ng/mL. Given the long half-life of IGF-1, evolution of IGF-1 and GH assays and limitations of GH suppression test, clinicians remain reliant on IGF-1 results 3–6 months following surgery to assess disease remission following surgical intervention. This can lead to delayed treatment of patients with persistent disease and significantly increase patient anxiety. Aim: To determine if IGF-1 levels at 6 weeks were equally predictive of surgical outcomes when compared to IGF-1 levels at 3–6 months postoperative. Methods: Retrospective review of patients with newly diagnosed acromegaly who had surgery between 2010–2019 and had post-operative IGF-1 level measured at 6 weeks and 3–6 months. IGF-1 was measured using the Siemens Immulite assay until 2016 when it was replaced by a LC-MS/MS assay. IGF-1 measurements at 6 weeks are obtained based on clinician discretion. Results: 69 patients (mean age 49 ± 14.8, female 31/69, 44.9%) with acromegaly had surgery and IGF-1 follow-up measurements at 6 weeks and 3–6 months. Persistent acromegaly was noted in 45/69 at 3–6 months. The median IGF-1 pre-operative was 701 ng/ mL (289–1600), 6 weeks postoperative was 286 ng/ mL (109–1038) and at 3–6 months was 267 ng/ mL (77–996). The median pre-operative IGF-1 was significantly higher than the median IGF-1 level at 6 weeks and 3–6 months (P=<0.001). Although a statistically significant difference was seen between IGF-1 levels at 6 weeks and 3–6 months, the mean difference between these time points was small (20 ng/mL, P=<0.001). There was a greater percent reduction in IGF-1 at 6 weeks following surgery in those who had a normal IGF-1 at 3–6 months compared to those who did not (63% vs 35%, P=<0.01). Among patients who were deemed in remission at 3–6 months (24/69, 35%), 3/24 patients (all male with macroadenoma and no cavernous sinus invasion) had mildly elevated IGF-1 levels at 6 weeks (≤1.12 upper limit of normal) which subsequently normalized. In all of these patients, GH was <1 ng/mL post-op. In 1 male (macroadenoma and cavernous sinus invasion), IGF-1 levels increased from normal at 6 weeks to abnormal when measured at 3–6 months. Conclusion: In the vast majority of patients, 6 weeks post-operative IGF-1 can be used to assess response to surgery avoiding a delay in treatment. However, we would recommend repeating IGF-1 levels at 3–6 months in those who have marginally elevated IGF-1 above normal (≤ 1.12), without cavernous sinus invasion and a post-operative GH of <1 ng/mL prior to intervening if the IGF-1 is elevated 6 weeks as the IGF-1 may normalize.

Abstract Introduction Varied presentations of vitamin B12 (B12) deficiency include hematologic (megaloblastic anemia) and neurologic (myelopathy, peripheral neuropathy). Delayed recognition and treatment may have serious consequences. Assessing B12 status can be challenging due to diverse laboratory assays and thresholds, resulting in a wide range of reported prevalence of B12 deficiency from 3-26%. Comorbidities may also spuriously elevate or suppress B12 levels. Methylmalonic acid (MMA) level, often used as a companion test to assess for B12 deficiency, may also be affected by differing laboratory thresholds and other medical comorbidities, such as renal dysfunction. Our institutional approach to B12 assessment, termed the pernicious anemia (PA) cascade, consists of reflexive testing to 1) document low B12 stores (B12 levels with or without MMA), and 2) diagnose pernicious anemia (intrinsic factor binding antibody [IFBA] with or without gastrin assay). In this study, our objectives were: (1) assess the usefulness of our B12 testing algorithm and associated laboratory thresholds for identifying B12 deficiency, and (2) evaluate clinical follow-up of test results as part of a quality project. Methods In this retrospective study, adult (age ≥18 years) inpatients who had B12 testing from 2007 to 2013 were identified. Medical records for those patients with B12 levels 150-400 ng/L were reviewed. Data abstracted included patient demographics, indication for B12 testing, B12 levels, results for MMA, IFBA, gastrin, serum creatinine, complete blood count, and clinical outpatient follow-up. The PA cascade algorithm is as follows: 1) for B12 <150 ng/L, IFBA is performed; 2) if IFBA is negative or indeterminate, then gastrin is performed; 3) for B12 150-400 ng/L, MMA is performed; 4) if MMA is >0.40 nmol/mL, then IFBA is performed. Reference range for B12 is 180-914 ng/L. Patients were determined to be B12 deficient if B12 level was <180 ng/L, or if B12 was 150-400 ng/L with elevated MMA and macrocytosis in the absence of significant renal dysfunction, defined as serum creatinine ≥2.0 mg/dL. Results Records of 326 patients (150 female) were reviewed. Indications for B12 testing were: hematologic, 175 patients (53.7%); neurologic, 127 patients (39.0 %), psychiatric, 18 patients (5.5%); other, 4 patients (1.2%). Fifty-nine of 326 (18.1%) patients were B12 deficient, of whom 17 of 59 (28.8%) had PA. There were 54 cases of elevated MMA, >0.40 nmol/mL, of which 30 cases had mildly elevated MMA, >0.40 nmol/mL and ≤0.60 nmol/mL, considered to be the MMA "gray zone". Thirty-two of the total 326 patients had serum creatinine ≥2.0 mg/dL, of which 23 patients also had elevated MMA. Elevated MMA in 13 of these 23 patients was more likely due to renal dysfunction than to B12 deficiency. B12 testing results were not mentioned in hospital discharge summaries for 173 patients, including 8 patients with B12 deficiency. For 22 B12-deficient patients, there was no documentation of B12 replacement. Conclusions The PA cascade detected B12 deficiency in a significant number of inpatients with low-normal B12 levels that might have otherwise been missed; 28.8% of this group had PA for whom long-term B12 replacement is indicated. As treatment for B12 deficiency is inexpensive, non-toxic, and non-invasive, it is reasonable to evaluate B12 status by cascade testing which may provide additional diagnostic data beyond B12 level. Notable clinical practice findings from this study include the lack of B12 results in 173 of 326 discharge summaries, and no record of B12 supplementation in 22 of 59 patients with B12 deficiency. These gaps in documentation and follow-up may be associated with the relatively long turnaround time of MMA testing. Efforts at improving documentation, communication, and treatment of B12 deficiency are ongoing. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction The CLSI EP15-A3 guideline “User Verification of Precision and Estimation of Bias” provides a simple experimental approach to estimate a method’s imprecision and bias. The objective is to determine if the laboratory precision performance of repeatability (SR) and within-laboratory imprecision (SWL) are in accordance to the manufacturer specification claims (MSCs). Objectives Evaluate the utility of the EP15-A3 protocol to verify method precision during a troubleshooting investigation and after major instrument maintenance, using a carcinoembryonic antigen (CEA) immunoassay as an example. Methods CEA was performed on the Beckman Coulter DxI (Beckman Coulter, Brea, CA). Quality control (QC) levels (L1: 2.89; L2: 21.10; L3: 39.10 ng/mL) (Bio-Rad Laboratories, Irvine, CA) were used. Each QC level was measured before and after instrument maintenance as follows: five replicates per run, one run per day, and during 5 days. Imprecision estimates (IEs) for SR (%CVR) and SWL (%CVWL) were calculated by one-way analysis of variance using Microsoft Excel Analyse-it software. Estimated imprecision was compared to MSC and desirable imprecision specifications based on biological variation (BV). Results A change in the analytical performance of CEA was detected by a decreased sigma-metric indicator. After a bias problem was ruled out, the observed %CVR for L1, L2, and L3 were 7.2%, 3.7%, and 4.8%, respectively. The %CVWL were 8.3%, 5.0%, and 5.5%, which exceeded the MSC of %CVWL~4.0% to 4.5%. After a laboratory investigation, major instrument maintenance was performed by the manufacturer. The %CVR and %CVWL estimates for L1, L2, and L3 after maintenance were 3.2%, 3.8%, 3.5% and 3.9%, 4.2%, 4.0%, respectively. After maintenance, the CEA performance was consistent with the MSC for each of the levels analyzed and within the BV impression goal of %CV ≤6.4. Conclusion CLSI EP15-A3 guideline is an alternative troubleshooting tool that can be used to investigate and verify method precision performance before and after significant instrument maintenance.

Abstract Background Pathologic causes of hyperprolactinemia include prolactin-secreting pituitary adenoma (prolactinoma), diseases of the hypothalamus, primary hypothyroidism, and renal failure. Another cause of hyperprolactinemia is the presence of macroprolactin, a high-molecular-mass complex of prolactin and immunoglobulins, which constitutes a biologically inactive form of prolactin. Detection of macroprolactin is important to avoid misdiagnosis and inappropriate treatment; however, relatively little is known about the persistence of macroprolactin in patients over time or how macroprolactin concentrations evolve within patients. The objective of this study was to examine the changes in macroprolactin and prolactin over time in a large clinical population. Methods All physician-ordered macroprolactin tests from December 2011 to October 2018 (n = 5,318 unique patients) were examined. Data were extracted from patients with repeat collections (≥2 timepoints) during this 7-year period (n = 269). Macroprolactin testing was performed using the Roche Elecsys Prolactin II assay. Prior to analysis, an equal volume of 25% polyethylene glycol (PEG) was added to patient serum, causing macroprolactin to precipitate. Following centrifugation, unprecipitated prolactin was measured in the supernatant, as well as an aliquot of the native sample (measuring total prolactin). Macroprolactin (precipitated prolactin) was calculated by subtracting the unprecipitated prolactin from the total prolactin concentration. For this study, a specimen was considered positive for macroprolactin if the percentage of precipitated prolactin was ≥60%. Results A total of 14% (37/269) of patients tested positive for macroprolactin in at least one of the sequential determinations. For all patients with two or more timepoints, the mean interdetermination change in percent macroprolactin was +0.6% and the mean interdetermination change in total prolactin was –11.6 ng/mL. The mean time between determinations in these patients was 303 days. For the 37 patients that had a positive macroprolactin determination, 25 remained positive across all sample collections (mean interdetermination change of +0.5% macroprolactin, mean interdetermination change in total prolactin of +0.4 ng/mL), seven samples went from positive to negative (mean interdetermination change of –10% macroprolactin, mean change in total prolactin of +0.2 ng/mL), and two samples went from negative to positive (mean interdetermination change of +5.5% macroprolactin, mean change in total prolactin of +1.3 ng/mL). The remaining 3 of the 37 specimens had more than two determinations that fluctuated above and below the predefined cutoff. Conclusions The results from this study suggest that the presence of macroprolactin largely but not exclusively persists over time. Additionally, macroprolactin rarely appears after a previously negative assessment (2/235 patients). Furthermore, only small increases in sequential percent macroprolactin determinations were observed in this data set. The prevalence of the persistence of macroprolactin protein over time might have important implications for patient prolactin monitoring.

Abstract Background Heterophile antibody (HAb) interferences in immunoassays can cause falsely elevated hCG concentrations leading to incorrect diagnosis and treatments options. When results are not consistent with the clinical findings, hCG HAb interference investigation may be requested by the physician. A retrospective evaluation of the frequency of HAb interference was performed among cases of physician-requested investigations and the effectiveness of commercially available blocking reagents to detect HAb interference in two immunoassay systems was evaluated. Methods One hundred and thirteen physician requests for hCG HAb investigation from 2008 to 2017 were reviewed. The primary method used to measure hCG was the Beckman Coulter Access Total βhCG (2008–2010) and the Roche Elecsys HCG+β (2014–2017). HAb investigation included measurement by two immunoassays before and after treatment of samples with heterophile blocking reagents and serial dilution studies. Results Five cases of HAb and HAb-like interference were identified. The interference frequency was 6.7% for the Beckman assay and 2.9% for the Roche assay. The presence of HAb was detected using heterophile blocking reagents and an alternative method in three cases. The other two cases were detected due to discrepant results with an alternative method and non-linear serial dilutions (HAb-like). Conclusions HAb interference was observed in the Beckman and the Roche assays. The heterophile blocking reagents failed to detect 40% of interference cases. Blocking reagents should not solely be used for these investigations. Multiple strategies including the use of serial dilutions and using an alternative platform are critical when troubleshooting interferences in hCG immunoassays.

Abstract Background: The GALAD score is a serum biomarker–based model that predicts the probability of having hepatocellular carcinoma (HCC) in patients with chronic liver disease. We aimed to assess the performance of the GALAD score in comparison with liver ultrasound for detection of HCC. Methods: A single-center cohort of 111 HCC patients and 180 controls with cirrhosis or chronic hepatitis B and a multicenter cohort of 233 early HCC and 412 cirrhosis patients from the Early Detection Research Network (EDRN) phase II HCC Study were analyzed. Results: The area under the ROC curve (AUC) of the GALAD score for HCC detection was 0.95 [95% confidence interval (CI), 0.93–97], which was higher than the AUC of ultrasound (0.82, P &lt;0.01). At a cutoff of −0.76, the GALAD score had a sensitivity of 91% and a specificity of 85% for HCC detection. The AUC of the GALAD score for early-stage HCC detection remained high at 0.92 (95% CI, 0.88–0.96; cutoff −1.18, sensitivity 92%, specificity 79%). The AUC of the GALAD score for HCC detection was 0.88 (95% CI, 0.85–0.91) in the EDRN cohort. The combination of GALAD and ultrasound (GALADUS score) further improved the performance of the GALAD score in the single-center cohort, achieving an AUC of 0.98 (95% CI, 0.96–0.99; cutoff −0.18, sensitivity 95%, specificity 91%). Conclusions: The performance of the GALAD score was superior to ultrasound for HCC detection. The GALADUS score further enhanced the performance of the GALAD score. Impact: The GALAD score was validated in the United States.