Endogenous anti-streptavidin antibodies causing erroneous laboratory results more common than anticipated.

All immunological methods are vulnerable to different kinds of interference. The purpose of this work was to study the cause and frequency of method-dependent interference in the Roche thyroid immunoassays. Serum samples with discordant thyroid function tests (TFT) were selected from samples sent to the Hormone Laboratory, Oslo University Hospital from June 2013 to September 2018. We identified 93 patients with discordant pathological TFT when analysed with the Roche methods and normal results when analysed with alternative methods. 42 of these samples were sent to Roche Diagnostics (Germany) for investigation of the interfering substance. Roche found interference to be caused by the presence of endogenous anti-streptavidin antibodies (ASA) (34 of 42 patients), ruthenium or the idiotype of the ruthenium labelled antibody (3 of 42 patients) and mouse antigens (1 of 42 patients). Method-dependent interference was estimated to affect 0.37% of the patients investigated in our laboratory. Interference due to the presence of endogenous ASA were further explored in other (non-thyroid) immunoassays by comparing analyte levels before and after pre-adsorption of the patients' sera with streptavidin-coated paramagnetic beads. An underestimation of hormone levels was observed in sandwich immunoassays, while an overestimation was found in competitive assays. Method-dependent interference in Roche thyroid immunoassays is caused mainly by ASA and is not a very rare phenomenon. Misleading results may lead to misdiagnosis and inappropriate medical treatment. The supplier of the assay should be alerted when the available alternative methodology reveals method-dependent errors.

Large method differences for free thyroid hormone assays in the hyperthyroid range can affect assessment of hyperthyroid status: Comparison of Abbott Alinity to Roche Cobas, Siemens Centaur and equilibrium dialysis LC-MS/MS.

BACKGROUND: Free T4 (FT4) determination is one of the most commonly performed biochemical tests in endocrinology. Treatment of thyroid dysfunctions is adjusted based on the severity of symptoms and biochemical test results. For Graves' hyperthyroidism, clinical guidelines recommend using FT4 as a (rough) guide to dose antithyroid drugs, together with other clinical information. It is well known that different platforms and methods give different FT4 results; however, large non-linear method differences at high FT4 concentrations are less well recognized. Current clinical guidelines do not make it clear that method differences in the hyperthyroid range can affect recommendations. METHOD: Serum samples from patients with very low (biochemically hypothyroid) to very high (hyperthyroid) concentrations of FT4 and/or free T3 (FT3) were analyzed using Abbott Alinity and compared to concentrations measured using Roche Cobas, Siemens ADVIA Centaur (FT4 only) and an in-house equilibrium dialysis liquid chromatography tandem mass spectrometry (LC-MS/MS) method. RESULTS: Alinity measured markedly lower FT4 and FT3 concentrations compared to the other methods, particularly at high FT4 concentrations. Regression analysis indicated that Alinity FT4 had a non-linear (curved) relationship to FT4 measured by the other methods. The method differences affected guideline-recommended treatments for hyperthyroidism. CONCLUSION: Measured free thyroid hormone concentrations are highly method-dependent, especially at high FT4 concentrations. Clinicians treating hyperthyroid patients should be aware that patients appear much less hyperthyroid from FT4-measurements performed using Alinity compared to Cobas or Centaur. Guideline-recommended antithyroid drug dosages based on FT4 (including multiples of the upper reference range) have to be adjusted to the FT4 method used. FT4 results from different methods should be clearly distinguished (e.g. separate lines) in medical records.

Adrenal steroid profiling as a diagnostic tool to differentiate polycystic ovary syndrome from nonclassic congenital adrenal hyperplasia: pinpointing easy screening possibilities and normal cutoff levels using liquid chromatography tandem mass spectrometry.

OBJECTIVE: To define liquid chromatography tandem mass spectrometry (LC-MS/MS)-based cutoff levels and panels of steroid hormones, to improve diagnosis of nonclassic congenital adrenal hyperplasia (NCCAH) and other partial enzyme defects in the adrenals. DESIGN: Prospective cohort analysis. SETTING: University hospital-based tertiary endocrine center. PATIENTS: One hundred and twenty-one healthy adults and 65 patients evaluated for possible NCCAH (validation cohort). INTERVENTIONS: The LC-MS/MS-determined cutoffs for 11 steroids (basal and cosyntropin-stimulated) were defined by 2.5% and 97.5% percentile in healthy subjects. Validation cohort was used for comparison. MAIN OUTCOME MEASURES: Percentage of patients diagnosed with NCCAH among patients with polycystic ovary syndrome (PCOS)-like symptomatology. Evaluation of the defined LC-MS/MS-based cutoff levels for steroid hormones among this patient group. RESULTS: Of the 65 PCOS-like patients evaluated for possible NCCAH, 8 (12.5%) were discovered and genetically verified, and 2 had classic congenital adrenal hyperplasia. Cosyntropin-stimulated 17-hydroxyprogesterone (17OHP) showed the best diagnostic accuracy for NCCAH with an area under the curve of 0.95 (0.89-1.0 with a sensitivity of 86% and a specificity of 88%. In homozygote patients, 21-deoxycortisol and 17OHP levels were elevated, in heterozygote patients only 17OHP (basal or stimulated) was raised. Four healthy patients in the validation cohort had 17OHP above the basal cutoff. CONCLUSIONS: The NCCAH syndrome is frequent in patients with suspected PCOS, and should be considered as a routine screening when assessing infertility. We suggest the use of serum steroid profiling, including 21-deoxycortisol, together with the cosyntropin stimulation test with 17OHP. Our data support a 17OHP cutoff of 8.5 nmol/L (2.8 ng/mL) 60 minutes after cosyntropin stimulation, when measured with LC-MS/MS, significantly lower than current European guidelines. CLINICAL TRIALS NUMBER: NCT0218660.

Maternal and Newborn Vitamin D-Binding Protein, Vitamin D Levels, Vitamin D Receptor Genotype, and Childhood Type 1 Diabetes.

OBJECTIVE: Circumstantial evidence links 25-hydroxy vitamin D [25(OH)D], vitamin D-binding protein (DBP), vitamin D-associated genes, and type 1 diabetes (T1D), but no studies have jointly analyzed these. We aimed to investigate whether DBP levels during pregnancy or at birth were associated with offspring T1D and whether vitamin D pathway genetic variants modified associations between DBP, 25(OH)D, and T1D. RESEARCH DESIGN AND METHODS: From a cohort of >100,000 mother/child pairs, we analyzed 189 pairs where the child later developed T1D and 576 random control pairs. We measured 25(OH)D using liquid chromatography-tandem mass spectrometry, and DBP using polyclonal radioimmunoassay, in cord blood and maternal plasma samples collected at delivery and midpregnancy. We genotyped mother and child for variants in or near genes involved in vitamin D metabolism (GC, DHCR7, CYP2R1, CYP24A1, CYP27B1, and VDR). Logistic regression was used to estimate odds ratios (ORs) adjusted for potential confounders. RESULTS: Higher maternal DBP levels at delivery, but not in other samples, were associated with lower offspring T1D risk (OR 0.86 [95% CI 0.74-0.98] per µmol/L increase). Higher cord blood 25(OH)D levels were associated with lower T1D risk (OR = 0.87 [95% CI 0.77-0.98] per 10 nmol/L increase) in children carrying the VDR rs11568820 G/G genotype (P interaction = 0.01 between 25(OH)D level and rs11568820). We did not detect other gene-environment interactions. CONCLUSIONS: Higher maternal DBP level at delivery may decrease offspring T1D risk. Increased 25(OH)D levels at birth may decrease T1D risk, depending on VDR genotype. These findings should be replicated in other studies. Future studies of vitamin D and T1D should include VDR genotype and DBP levels.

Assay of steroids by liquid chromatography-tandem mass spectrometry in monitoring 21-hydroxylase deficiency.

Immunoassays of steroid hormones are still used in the diagnosis and monitoring of patients with congenital adrenal hyperplasia. However, cross-reactivity between steroids can give rise to falsely elevated steroid levels. Here, we compare the use of immunoassays and liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the monitoring of patients with classic 21-hydroxylase deficiency (21OHD). Steroid profiles in different mutation groups (genotypes) were also compared. Fifty-five patients with classic 21OHD (38 women) were studied. Blood samples were collected in the morning after an overnight medication fast. LC-MS/MS and immunoassays were employed to assay 17-hydroxyprogesterone (17OHP), testosterone and androstenedione. In addition, 21-deoxycortisol (21DF), 11-deoxycortisol (11DF), corticosterone, deoxycorticosterone, cortisone and cortisol were analyzed by LC-MS/MS. Testosterone, androstenedione and 17OHP levels were consistently lower (by about 30-50%) when measured by LC-MS/MS compared with immunoassays, with exception of testosterone in men. There was a significant correlation between 21DF and 17OHP (r = 0.87, P < 0.001), but three patients had undetectable 21DF. Subjects with no enzyme activity had significantly lower mean 11DF concentrations than subjects with residual activity. The use of LC-MS/MS gives a more specific view of adrenal steroid levels in 21OHD compared with immunoassays, which seem to considerably overestimate the levels of 17OHP and androstenedione. Falsely elevated levels of 17OHP and androstenedione could lead to overtreatment with glucocorticoids.

The Short Cosyntropin Test Revisited: New Normal Reference Range Using LC-MS/MS.

Background: The cosyntropin test is used to diagnose adrenal insufficiency (AI) and nonclassical congenital adrenal hyperplasia (NCCAH). Current cutoffs for cortisol and 17-hydroxyprogesterone (17-OHP) are derived from nonstandardized immunoassays. Liquid chromatography tandem mass spectrometry (LC-MS/MS) offers direct measurement of steroids, prompting the need to re-establish normal ranges. Objective: The goal of this study was to define cutoff values for cortisol and 17-OHP in serum by LC-MS/MS 30 and 60 minutes after intravenous administration of 250 µg tetracosactide acetate to healthy volunteers and to compare the results with LC-MS/MS with routine immunoassays. Methods: Cosyntropin testing was performed in healthy subjects (n = 138) and in patients referred for evaluation of adrenocortical function (n = 94). Steroids were assayed by LC-MS/MS and compared with two immunoassays used in routine diagnostics (Immulite and Roche platforms). The cutoff level for cortisol was defined as the 2.5% percentile in healthy subjects not using oral estrogens (n = 121) and for 17-OHP as the 97.5% percentile. Results: Cortisol cutoff levels for LC-MS/MS were 412 and 485 nmol/L at 30 and 60 minutes, respectively. Applying the new cutoffs, 13 of 60 (22%) subjects who had AI according to conventional criteria now had a normal test result. For 17-OHP, the cutoff levels were 8.9 and 9.0 nmol/L at 30 and 60 minutes, respectively. Conclusions: LC-MS/MS provides cutoff levels for cortisol and 17-OHP after cosyntropin stimulation that are lower than those based on immunoassays, possibly because cross-reactivity between steroid intermediates and cortisol is eliminated. This reduces the number of false-positive tests for AI and false-negative tests for NCCAH.

Vitamin D levels, brain volume, and genetic architecture in patients with psychosis.

BACKGROUND: Lower vitamin D levels are found in people with schizophrenia and depressive disorders, and also associated with neuroimaging abnormalities such as reduced brain volume in both animals and humans. Reduced whole brain and increased ventricular volume are also systematically reported in schizophrenia. Even though vitamin D deficiency has been proposed as a risk mechanism for schizophrenia there exist no studies to date of the association between vitamin D levels and brain volume in this population. Therefore, we investigated the relationship between vitamin D levels and brain phenotypes in psychotic disorders, and assessed possible interactions with genetic variants in vitamin D receptor (VDR) and other genetic variants that play a role in vitamin D levels in the body. METHODS: Our sample consisted of 83 psychosis patients and 101 healthy controls. We measured vitamin D levels as serum 25-hydroxyvitamin D. All participants were genotyped and neuroimaging conducted by structural magnetic resonance imaging. RESULTS: Vitamin D levels were significantly positively associated with peripheral grey matter volume in patients (ß 860.6; 95% confidence interval (CI) 333.4-1466, p < .003). A significant interaction effect of BSML marker (rs1544410) was observed to mediate the association between patient status and both white matter volume (ß 23603.3; 95% CI 2732.8-48708.6, p < .05) and whole brain volume (ß 46670.6, 95% CI 8817.8-93888.3, p < .04). Vitamin D did not predict ventricular volume, which rather was associated with patient status (ß 4423.3, 95% CI 1583.2-7267.8p < .002) and CYP24A1 marker (rs6013897) (ß 2491.5, 95% CI 269.7-4978.5, p < .04). CONCLUSIONS: This is the first study of the association between vitamin D levels and brain volume in patients with psychotic disorders that takes into account possible interaction with genetic polymorphisms. The present findings warrant replication in independent samples.

Vitamin D Deficiency Associated With Cognitive Functioning in Psychotic Disorders.

BACKGROUND: Cognitive dysfunctions are core features of psychotic disorders with substantial impact on daily functioning. Vitamin D deficiency has been found to be related to cognitive dysfunctions, but the associations between vitamin D deficiency and cognition in persons with a psychotic disorder are largely unknown. METHODS: This cross-sectional study included 225 patients with a DSM-IV psychotic disorder consecutively recruited from 2003 to 2014 and 159 randomly selected healthy controls, assessed by a cognitive test battery, a clinical protocol (including Structured Clinical Interview for DSM-IV Axis I Disorders and Positive and Negative Syndrome Scale), and a physical examination including vitamin D measurements. Multiple regression models were performed to evaluate the effect of vitamin D deficiency (defined serum 25-hydroxyvitamin D [25(OH)D] < 25 nmol/L) on key cognitive domains: processing speed, verbal learning, verbal memory, and executive functioning. RESULTS: Vitamin D deficiency was significantly associated with decreased processing speed (ie, Digit Symbol Coding) (t = -2.6, P = .01; total model: adjusted R² = 0.40, F6, 374 = 43.8, P < .001) and decreased fluency (ie, verbal fluency) (t = -2.1, P = .04; total model: adjusted R² = 0.35, F6, 373 = 34.2, P < .001) when the results were controlled for age, ethnicity, IQ, patient versus control status, and substance or alcohol abuse. Additional analyses indicated that negative symptoms diluted the association between vitamin D deficiency and processing speed (t = -1.72, P = .09) and verbal fluency (t = -1.35, P = .18) in patients. CONCLUSION: The associations between vitamin D deficiency and processing speed and verbal fluency are good arguments for planning large-scale randomized controlled studies in target populations so conclusions can be made about the potential beneficial effect of vitamin D on cognition in psychotic disorders.

Maternal and neonatal vitamin D status, genotype and childhood celiac disease.

BACKGROUND: Low concentration of 25-hydroxyvitamin D during pregnancy may be associated with offspring autoimmune disorders. Little is known about environmental triggers except gluten for celiac disease, a common immune-mediated disorder where seasonality of birth has been reported as a risk factor. We therefore aimed to test whether low maternal and neonatal 25-hydroxyvitamin D predicted higher risk of childhood celiac disease. METHODS AND FINDINGS: In this Norwegian nationwide pregnancy cohort (n = 113,053) and nested case-control study, we analyzed 25-hydroxyvitamin D in maternal blood from mid-pregnancy, postpartum and cord plasma of 416 children who developed celiac disease and 570 randomly selected controls. Mothers and children were genotyped for established celiac disease and vitamin D metabolism variants. We used mixed linear regression models and logistic regression to study associations. There was no significant difference in average 25-hydroxyvitamin D between cases and controls (63.1 and 62.1 nmol/l, respectively, p = 0.28), and no significant linear trend (adjusted odds ratio per 10 nM increase 1.05, 95% CI: 0.93-1.17). Results were similar when analyzing the mid-pregnancy, postpartum or cord plasma separately. Genetic variants for vitamin D deficiency were not associated with celiac disease (odds ratio per risk allele of the child, 1.00; 95% CI, 0.90 to 1.10, odds ratio per risk allele of the mother 0.94; 95% CI 0.85 to 1.04). Vitamin D intake in pregnancy or by the child in early life did not predict later celiac disease. Adjustment for established genetic risk markers for celiac disease gave similar results. CONCLUSIONS: We found no support for the hypothesis that maternal or neonatal vitamin D status is related to the risk of childhood celiac disease.

Low vitamin D is associated with negative and depressive symptoms in psychotic disorders.

BACKGROUND: There are indications that low S-25(OH)D is associated with increased disease severity in psychotic disorder. Our first aim was to investigate the relations between low S-25(OH)D and positive, negative and depressive symptoms. Our second aim was to explore if associations between S-25(OH)D and symptoms were influenced by levels of inflammatory markers. METHODS: Participants (N=358) with a medical history of one or more psychotic episodes were recruited. Current symptomatology was assessed by The Structured Interview for the Positive and Negative Syndrome Scaleanalyzed by a five-factor model. The Calgary Depression Scale for Schizophrenia was used to assess depression and suicidal ideation. Blood samples were analyzed for S-25(OH)D, CRP, sTNF-R1, IL-Ra and OPG. We performed bivariate correlations and multiple regression models to evaluate the effect of S-25(OH)D on the outcomes. RESULTS: Low S-25(OH)D was significantly associated with negative symptoms (adjusted R2=0.113, F(6,357)=8.58, p<0.001) and with depression (adjusted R2=0.045, F(4,357)=5.233, p<0.001) when adjusting for possible confounding factors (i.e. gender, education, diagnose, hospitalization status, ethnicity, season and thyroid status). CRP was correlated with both S-25(OH)D (rho=-0.13, p=0.02) and negative symptoms (rho=0.14, p=0.01), but did not act as a mediator. The correlations between S-25(OH)D and the inflammatory markers sTNF-R1, IL-Ra and OPG were not significant. CONCLUSION: There is a strong association between low S-25(OH)D and higher negative and depressive symptoms in psychotic disorders. Randomized controlled trials should be performed to investigate the effect of vitamin D supplementation as adjuvant treatment strategy in patients with prominent negative or depressive symptoms.