False diagnosis of recurrent thyroid carcinoma: the importance of testing for heterophile antibodies.

Thyroglobulin (Tg) levels are important to predict recurrence in differentiated thyroid cancer patients.However, false-positive results can hence the request of unnecessary tests and treatments. We reported two cases of interference in thyroglobulin measurement and the workup to investigate them. Both patients achieved an excellent response to therapy after total thyroidectomy and one patient had also received radioiodine treatment. During the follow-up, Tg levels increased and there was no evidence of recurrent disease in the imaging studies. The Tg levels by the Access platform were positive but the results by Elecsys platform and LC-MS/MS were undetectable, leading to the hypothesis of heterophile antibodies (HAbs) interference. The possibility of HAbs interference must be considered when the Tg levels do not fit in the clinical picture. The measurement of Tg by another immunoassay or by LC-MS/MS may be useful in these situations.

Alert for the high prevalence of vitamin D deficiency in adolescents in a large Brazilian sample.

OBJECTIVE: To estimate the prevalence of vitamin D deficiency and severe deficiency in children and adolescents, in a large Brazilian sample. METHODOLOGY: Results of 413,988 25(OH)D measurements in children and adolescents aged 0 to 18 years collected between 01/2014 and 10/2018 were obtained from the database of a Clinical Laboratory. In this population, 25 hydroxyvitamin D concentrations below 20 ng/mL are considered deficient, and below 12 ng/mL as severe deficiency. All measurements were performed by immunoassay and the results were distributed by gender, age group, seasonality, and latitude. RESULTS: The mean of 25(OH)D levels was 29.2 ng/mL with a standard deviation of 9.2 ng/mL. Of the total samples, 0.8% had a concentration < 12 ng/mL, and 12.5% of the samples had a concentration < 20 ng/mL, with a higher prevalence in females. Children under 2 years of age had the lowest prevalence. The effects of latitude and seasonality were quite evident. In samples of female adolescents from the southern region in winter, 36% of vitamin D deficiency and 5% of severe deficiency were found. CONCLUSION: In this large number of measurements of 25(OH)D in children and adolescents, 12.5% had a deficiency and 0.8% had severe deficiency. A greater deficiency was observed among adolescents, especially females, which raises questions about the need for supplementation during this period of life.

Concentrations of total, bioavailable, and free 25OHD in individuals with and without primary hyperparathyroidism and their correlations to DXA and trabecular bone score.

Objective: This study aimed to investigate the association between 25OHD (total, bioavailable and free) with bone mass and microarchitecture among primary hyperparathyroidism (PHPT) patients and controls. Subjects and methods: Sixty-four patients in the preoperative period of PHPT and 63 matched controls, who had not taken vitamin D in the last three months. To calculate the bioavailable and free 25OHD, the genetic variants of the vitamin D-binding protein (DBP) were determined. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry (DXA). The distributions of total, bioavailable and free 25OHD and their correlation with TBS and DXA were evaluated. Results: PHPT showed BMD and TBS values lower than CTRL in all locations (p < 0.05). There were no statistical differences in the levels of free, bioavailable and total 25OHD between the PHPT and CTRL groups [mean, min-max: 3.4 (1.4-8.6) vs. 3.1 (1.0- 9.8) pg/mL, 1.51 (0.43-3.58) vs. 1.41 (0.38-3.48) ng/mL, 22.6 (11.0-39.9) vs. 20.6 (8.9-35.3) ng/dL, respectively; (p > 0.05). The distribution of DBP haplotypes was similar between groups. DXA showed no correlation with any form of 25OHD in both groups. TBS presented a weak correlation with the total 25OHD in PHPT (r = 0.28; p = 0.02) and a moderate correlation with the total, free and bioavailable 25OHD in CTRL (r = 0.42; r = 0.42; r = 0.43; respectively, p < 0.01). Conclusion: The concentrations of total, free and bioavailable 25OHD were similar in both the PHPT and control groups. 25OHD concentrations correlated positively with TBS and not with DXA, especially in controls, suggesting that this method may be more sensitive to assessing the consequences of vitamin D deficiency on bone quality in individuals without PHPT.

Levels of bioavailable, and free forms of 25(OH)D after supplementation with vitamin D3 in primary hyperparathyroidism.

The 25 hydroxyvitamin D [25(OH)D] is the major metabolite for ascertaining vitamin D status, which circulates bound to a specific carrier (vitamin D-binding protein - VDBP). A portion that circulates unbound vary according to the VDBP genotype. This study evaluates the behavior of different forms of 25(OH)D, before and after supplementation with 14,000 IU of vitamin D3, weekly for 12 weeks, in individuals with primary hyperparathyroidism and controls. Fifty-six patients with active primary hyperparathyroidism (PHPT) and 64 paired controls (CTRL), not taking vitamin D3 for the last three months, were enrolled. The genetic isotypes of VDBP were determined to calculate bioavailable and free 25(OH)D. A p < 0.05 was considered significant. There were no statistical differences in free, bioavailable, and total 25(OH)D levels between PHPT and CTRL groups at baseline. The distribution of VDBP haplotypes 1s/1s, 1f/1f, 1s/1f, 2/2, 1s/2, and 1f/2 was similar between groups. After supplementation, all three forms of 25(OH)D proportionally increased within each group, although the percentage increment was lower in the PHPT group (p < 0.05). Total 25(OH)D is better correlated with PTH in the PHPT group than bioavailable and free 25(OH)D (r = -0.41; p < 0.05). The concentrations of total, free, and bioavailable 25(OH)D were similar in both PHPT and CTRL groups, and all forms increased proportionally after supplementation, although this increment percentage was higher in the CTRL group, with a subsequent reduction of PTH and AP. Total 25(OH)D correlated better with PTH than other forms, suggesting no advantages in measuring free or bioavailable 25(OH)D in these situations.

Concentrations of total, bioavailable, and free 25OHD in individuals with and without primary hyperparathyroidism and their correlations to DXA and trabecular bone score

ABSTRACT Objective: This study aimed to investigate the association between 25OHD (total, bioavailable and free) with bone mass and microarchitecture among primary hyperparathyroidism (PHPT) patients and controls. Subjects and methods: Sixty-four patients in the preoperative period of PHPT and 63 matched controls, who had not taken vitamin D in the last three months. To calculate the bioavailable and free 25OHD, the genetic variants of the vitamin D-binding protein (DBP) were determined. Bone mineral density (BMD) was determined by dual-energy X-ray absorptiometry (DXA). The distributions of total, bioavailable and free 25OHD and their correlation with TBS and DXA were evaluated. Results: PHPT showed BMD and TBS values lower than CTRL in all locations (p < 0.05). There were no statistical differences in the levels of free, bioavailable and total 25OHD between the PHPT and CTRL groups [mean, min-max: 3.4 (1.4-8.6) vs. 3.1 (1.0-9.8) pg/mL, 1.51 (0.43-3.58) vs. 1.41 (0.38-3.48) ng/mL, 22.6 (11.0-39.9) vs. 20.6 (8.9-35.3) ng/dL, respectively; (p > 0.05). The distribution of DBP haplotypes was similar between groups. DXA showed no correlation with any form of 25OHD in both groups. TBS presented a weak correlation with the total 25OHD in PHPT (r = 0.28; p = 0.02) and a moderate correlation with the total, free and bioavailable 25OHD in CTRL (r = 0.42; r = 0.42; r = 0.43; respectively, p < 0.01). Conclusion: The concentrations of total, free and bioavailable 25OHD were similar in both the PHPT and control groups. 25OHD concentrations correlated positively with TBS and not with DXA, especially in controls, suggesting that this method may be more sensitive to assessing the consequences of vitamin D deficiency on bone quality in individuals without PHPT.

Reassessment of predictive values of ACTH-stimulated serum 21-deoxycortisol and 17-hydroxyprogesterone to identify CYP21A2 heterozygote carriers and nonclassic subjects.

INTRODUCTION: Heterozygotes (HZs) for 21-hydroxylase deficiency (21OHD) are highly prevalent, ranging from 1:60 to 1:11 for classic and nonclassic (NC) forms, respectively. Detection of HZ and asymptomatic NC by CYP21A2 genotyping is valuable for genetic counselling, but costly, complex and narrowly available. Adrenocorticotropic hormone (ACTH)-stimulated serum 17-hydroxyprogesterone (17P) and 21-deoxycortisol (21DF) discriminate 21OHD phenotypes effectively, notably if measured simultaneously by liquid chromatography-tandem mass spectrometry (LC-MS/MS). OBJECTIVE: This study was performed to reassess former LC-MS/MS-defined post-ACTH 21DF, 17P and cortisol (F) cutoffs in family members at risk for 21OHD. DESIGN AND PATIENTS: Prospective study in which we screened 58 asymptomatic relatives from families with 21OHD patients and compared post-ACTH steroid phenotypes with subsequent genotypes. RESULTS: Post-ACTH 21DF, 17P, F and (21DF + 17P)/F ratio segregate NC, HZ and wild-type (WT) phenotypes (subsequently genotyped) with some overlap. New receiver operating characteristic curve-defined cutoffs for post-ACTH 21DF, 17P and (21DF + 17P)/F ratio are 60 ng/dl, 310 ng/dl and 12 (unitless). Twenty-six of 33 HZ and all 6 NC (82.1%) had post-ACTH 21DF > 60 and 17P > 310 ng/dl, whereas 17/19 WT (89.5%) had values below cutoffs. Post-ACTH 21DF and 17P had a strong positive correlation (r = .9558; p < .001). A (21DF + 17P)/F ratio > 12 correctly identified 36 of 39 HZ plus NC (92.3% sensitivity) with 84.2% specificity (16 of 19 WT). Given the high frequency of 21OHD HZ, the negative prediction of ratio values below 12 excludes heterozygosity in 99.8% and 99.1% for classic and NC mutations, respectively. CONCLUSIONS: Reassessed ACTH-stimulated 21DF and 17P cutoffs by LC-MS/MS (60 and 310 ng/dl, respectively) correctly recognised 82.5% HZ plus NC, but combined precursor-to-product ratio ([21DF + 17P]/F) cutoff of 12 was superior, identifying 92.3% HZ plus NC. Since one WT subject is an outlier (potential HZ), these values would be somewhat better reinforcing their utility for screening asymptomatic relatives at risk for 21OHD.

No association between vitamin D status and COVID-19 infection in São Paulo, Brazil

ABSTRACT In recent years the immunomodulatory actions of vitamin D, a steroid hormone, have been extensively studied. In 2020, due to the COVID-19 pandemic, the question arose as to 25(OH)D status would be related to susceptibility to SARS-CoV-2 infection, since several studies pointed out a higher prevalence and severity of the disease in populations with low levels of 25(OH)D. Thus, we investigated the 25(OH)D levels in adults "Detected" positive for SARS CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) test, and in negative controls, "not Detected", using the Fleury Group's examination database, in Sao Paulo, Brazil. Of a total of 14.692 people with recent assessments of 25(OH)D and RT-PCR tests for COVID-19, 2.345 were positive and 11.585 were negative for the infection. The groups did not differ in the percentage of men and women, or in the age distribution. There were no differences in the distribution of 25(OH)D between the two groups (p = 0.08); mean 25(OH)D of 28.8 ± 21.4 ng/mL and 29.6 ± 18.1 ng/mL, respectively. In the specific population studied, clinical, environmental, socioeconomic and cultural factors should have greater relevance than 25(OH)D in determining the susceptibility to COVID-19.

Trabecular Bone Score (TBS) in Primary Hyperparathyroidism (PHPT): A Useful Tool?

Primary Hyperparathyroidism (PHPT) often leads to bone loss, even in its asymptomatic presentations. Trabecular Bone Score (TBS) is a method to assess the trabecular bone structure of the spine. This study aimed to evaluate TBS measurements combined with Dual X-ray Absorptiometry (DXA) values in the search for more accurate bone fragility risk assessment among PHPT patients. From 2017 to 2019, patients diagnosed with PHPT (n = 64), before surgery, were invited to participate in this study. Bone mineral density (BMD) by DXA at the lumbar spine, total hip, femoral neck, distal third radius, and TBS were determined in patients and controls (n = 63). The vertebral fracture was defined using the Genant method in vertebral images by DXA and vertebral fracture assessment (VFA). Patients and controls did not differ in age, sex, menopausal status, or body mass index (BMI). The PHPT patients presented significantly lower BMD values than the controls in all sites evaluated. The TBS measurements were also statistically lower in PHPT patients than controls (mean TBS PHPT = 1.233 vs TBS controls = 1.280, p = 0.044). Osteoporosis was observed in 50% of PHPT patients and 26.6% of controls (p = 0.02). However, lumbar spine T-Score < -2.5 was observed only in 21.8% of PHPT patients. Vertebral fractures were detected in nine individuals (14%) from the PHPT group and four (6.3%) in the controls (p = 0.24). The TBS area under the curve (AUC) was higher than DXA AUC in all sites, for vertebral fracture assessment. The TBS AUC was significant in the PHPT group (0.75, 95% CI 0.62 - 0.88, p = 0.02) and not significant in the DXA analysis. The ROC curve showed that TBS values < 1.187 are associated with a significantly higher risk of vertebral fracture among PHPT patients (p = 0.02). The TBS used as a complement to DXA measurements is a useful tool which may better assess fragility risk among PHPT patients.

No association between vitamin D status and COVID-19 infection in São Paulo, Brazil.

In recent years the immunomodulatory actions of vitamin D, a steroid hormone, have been extensively studied. In 2020, due to the COVID-19 pandemic, the question arose as to 25(OH)D status would be related to susceptibility to SARS-CoV-2 infection, since several studies pointed out a higher prevalence and severity of the disease in populations with low levels of 25(OH)D. Thus, we investigated the 25(OH)D levels in adults "Detected" positive for SARS CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) test, and in negative controls, "not Detected", using the Fleury Group's examination database, in Sao Paulo, Brazil. Of a total of 14.692 people with recent assessments of 25(OH)D and RT-PCR tests for COVID-19, 2.345 were positive and 11.585 were negative for the infection. The groups did not differ in the percentage of men and women, or in the age distribution. There were no differences in the distribution of 25(OH)D between the two groups (p = 0.08); mean 25(OH)D of 28.8 ± 21.4 ng/mL and 29.6 ± 18.1 ng/mL, respectively. In the specific population studied, clinical, environmental, socioeconomic and cultural factors should have greater relevance than 25(OH)D in determining the susceptibility to COVID-19.

Global FT4 immunoassay standardization: an expert opinion review.

OBJECTIVES: Results can vary between different free thyroxine (FT4) assays; global standardization would improve comparability of results between laboratories, allowing development of common clinical decision limits in evidence-based guidelines. CONTENT: We summarize the path to standardization of FT4 assays, and challenges associated with FT4 testing in special populations, including the need for collaborative efforts toward establishing population-specific reference intervals. The International Federation of Clinical Chemistry and Laboratory Medicine Committee for Standardization of Thyroid Function Tests has undertaken FT4 immunoassay method comparison and recalibration studies and developed a reference measurement procedure that is currently being validated. Further studies are needed to establish common reference intervals/clinical decision limits. Standardization of FT4 assays will change test results substantially; therefore, a major education program will be required to ensure stakeholders are aware of the benefits of FT4 standardization, planned transition procedure, and potential clinical impact of the changes. Assay recalibration by manufacturers and approval process simplification by regulatory authorities will help minimize the clinical impact of standardization. SUMMARY: Significant progress has been made toward standardization of FT4 testing, but technical and logistical challenges remain. OUTLOOK: Collaborative efforts by manufacturers, laboratories, and clinicians are required to achieve successful global standardization of the FT4 assays.

The role of a new polyclonal competitive thyroglobulin assay in the follow-up of patients with differentiated thyroid cancer with structural disease but low levels of serum thyroglobulin by immunometric and LC-MS/MS methods.

PURPOSE: The aims of this study were to assess the role of an in-house competitive thyroglobulin assay (Tg-c) in the follow-up of metastatic differentiated thyroid carcinoma (DTC) patients who presented underestimated Tg measurements by immunometric assays (Tg-IMA) and to compare the results with IMA and LC-MS/MS Tg methods. METHODS: This prospective study included 40 patients. Twenty-one with metastatic disease: 14 had Tg-IMA levels inappropriately low or undetectable (eight patients with positive and six with borderline TgAb) and seven had high Tg-IMA levels. Nineteen had an excellent response to therapy. The competitive assay employs a polyclonal antibody produced in rabbits immunized with human Tg, Tg labeled with biotin, and for the solid phase separation, a monoclonal anti-rabbit IgG antibody adsorbed to microtiter plates. RESULTS: All 14 patients with structural disease and underestimated levels of Tg-IMA presented detectable Tg-c levels. The median Tg-c level in the group with positive TgAb was 183 µg/L (range: 22-710 µg/L), and 58 µg/L (range 23-148 µg/L) in the borderline TgAb group. The levels of Tg-LC-MS/MS were detectable in some patients (range < 0.5-18 µg/L). All seven patients with high Tg-IMA presented also high levels of Tg-c. Only 2/19 patients with excellent response had Tg-c levels above the functional sensitivity. CONCLUSIONS: The competitive assay was able to detect Tg in all patients, even in the presence of serum TgAb, and may be an option in patients with underestimated Tg-IMA and relevant structural disease.

Prediction of bone mass changes after successful parathyroidectomy using biochemical markers of bone metabolism in primary hyperparathyroidism: is it clinically useful?

OBJECTIVE: To measure type 1 serum amino-terminal propeptide procollagen (P1NP) and type 1 cross-linked C-terminal telopeptide collagen (CTX) before parathyroidectomy (PTX) in PHPT patients, correlating these measurements with bone mineral density (BMD) changes. SUBJECTS AND METHODS: 31 primary hyperparathyroidism (HPTP) were followed from diagnosis up to 12-18 months after surgery. Serum levels of calcium, parathyroid hormone (PTH) vitamin D, CTX, P1NP, and BMD were measured before and 1 year after surgery. RESULTS: One year after PTX, the mean BMD increased by 8.6%, 5.5%, 5.5%, and 2.2% in the lumbar spine, femoral neck (FN), total hip (TH), and distal third of the nondominant radius (R33%), respectively. There was a significant correlation between BMD change 1 year after the PTX and CTX (L1-L4: r = 0.614, p < 0.0003; FN: r = 0.497, p < 0.0051; TH: r = 0.595, p < 0.0005; R33%: r = 0.364, p < 0.043) and P1NP (L1-L4: r = 0,687, p < 0,0001; FN: r = 0,533, p < 0,0024; TH: r = 0,642, p < 0,0001; R33%: r = 0,467, p < 0,0079) preoperative levels. The increase in 25(OH)D levels has no correlation with BMD increase (r = -0.135; p = 0.4816). On linear regression, a minimum preoperative CTX value of 0.331 ng/mL or P1NP of 37.9 ng/mL was associated with a minimum 4% increase in L1-L4 BMD. In TH, minimum preoperative values of 0.684 ng/mL for CTX and 76.0 ng/mL for P1NP were associated with a ≥ 4% increase in BMD. CONCLUSION: PHPT patients presented a significant correlation between preoperative levels of turnover markers and BMD improvement 1 year after PTX.

Prediction of bone mass changes after successful parathyroidectomy using biochemical markers of bone metabolism in primary hyperparathyroidism: is it clinically useful?

ABSTRACT Objective To measure type 1 serum amino-terminal propeptide procollagen (P1NP) and type 1 cross-linked C-terminal telopeptide collagen (CTX) before parathyroidectomy (PTX) in PHPT patients, correlating these measurements with bone mineral density (BMD) changes. Subjects and methods 31 primary hyperparathyroidism (HPTP) were followed from diagnosis up to 12-18 months after surgery. Serum levels of calcium, parathyroid hormone (PTH) vitamin D, CTX, P1NP, and BMD were measured before and 1 year after surgery. Results One year after PTX, the mean BMD increased by 8.6%, 5.5%, 5.5%, and 2.2% in the lumbar spine, femoral neck (FN), total hip (TH), and distal third of the nondominant radius (R33%), respectively. There was a significant correlation between BMD change 1 year after the PTX and CTX (L1-L4: r = 0.614, p < 0.0003; FN: r = 0.497, p < 0.0051; TH: r = 0.595, p < 0.0005; R33%: r = 0.364, p < 0.043) and P1NP (L1-L4: r = 0,687, p < 0,0001; FN: r = 0,533, p < 0,0024; TH: r = 0,642, p < 0,0001; R33%: r = 0,467, p < 0,0079) preoperative levels. The increase in 25(OH)D levels has no correlation with BMD increase (r = -0.135; p = 0.4816). On linear regression, a minimum preoperative CTX value of 0.331 ng/mL or P1NP of 37.9 ng/mL was associated with a minimum 4% increase in L1-L4 BMD. In TH, minimum preoperative values of 0.684 ng/mL for CTX and 76.0 ng/mL for P1NP were associated with a ≥ 4% increase in BMD. Conclusion PHPT patients presented a significant correlation between preoperative levels of turnover markers and BMD improvement 1 year after PTX.

More than kin, less than kind: one family and the many faces of diabetes in youth

SUMMARY Identification of the correct etiology of diabetes brings important implications for clinical management. In this report, we describe a case of a 4-year old asymptomatic girl with diabetes since age 2, along with several individuals in her family with different etiologies for hyperglycemia identified in youth. Genetic analyses were made by Sanger sequencing, laboratory measurements included HbA1c, lipid profile, fasting C-peptide, pancreatic auto-antibodies (glutamic acid decarboxylase [GAD], Islet Antigen 2 [IA-2], and anti-insulin). We found a Gly178Ala substitution in exon 5 of GCK gene in three individuals co-segregating with diabetes, and type 1 diabetes was identified in two other individuals based on clinical and laboratory data. One individual with previous gestational diabetes and other with prediabetes were also described. We discuss difficulties in defining etiology of hyperglycemia in youth in clinical practice, especially monogenic forms of diabetes, in spite of the availability of several genetic, laboratory, and clinical tools.

Novel immunoassay for TSH measurement in rats.

Measuring thyroid hormones is an important aspect for the study of metabolism and for monitoring diseases in both human and animal models. The traditional method for hormone measurement in rats is the radioimmunoassay (RIA). However, the RIA is associated with some practical disadvantages, including the use of radioactive material, the need for specialized equipment and expert staff, the short shelf-life of kits according to the half-life of the radioisotope and high costs. The objective of this study was to develop a new cost-effective method for measuring TSH levels in rats that avoids the use of radioactive material. We developed an in-house competitive immunoassay using a reference standard, polyclonal antibody produced in rabbits and biotinylated antigen. This method was tested in 64 Wistar rats that were divided into a control group (n = 41) and a group with hypothyroidism (n = 23). Our assay demonstrated an analytical sensitivity of 0.24 ng/mL (n = 12) and an intra-assay coefficient of variation (CV) of 8.9% for sera with TSH levels of 1.5 ng/mL and 13.2% for sera with TSH levels of 17.5 ng/mL (n = 14). The inter-assay CV was 13.5% for sera with TSH levels of 1.4 ng/mL and 14.5% for TSH levels of 18.2 ng/mL (n = 5). The analysis of mean TSH levels in control rats (5.06 ± 0.5701) and hypothyroid rats (51.09 ± 5.136) revealed a statistically significant difference (p < 0.001) between the groups. This method showed good sensitivity, can be automated and is low-cost compared with RIA. Our method offers a viable alternative for TSH measurement in rats.

Novel immunoassay for TSH measurement in rats

ABSTRACT Measuring thyroid hormones is an important aspect for the study of metabolism and for monitoring diseases in both human and animal models. The traditional method for hormone measurement in rats is the radioimmunoassay (RIA). However, the RIA is associated with some practical disadvantages, including the use of radioactive material, the need for specialized equipment and expert staff, the short shelf-life of kits according to the half-life of the radioisotope and high costs. The objective of this study was to develop a new cost-effective method for measuring TSH levels in rats that avoids the use of radioactive material. We developed an in-house competitive immunoassay using a reference standard, polyclonal antibody produced in rabbits and biotinylated antigen. This method was tested in 64 Wistar rats that were divided into a control group (n = 41) and a group with hypothyroidism (n = 23). Our assay demonstrated an analytical sensitivity of 0.24 ng/mL (n = 12) and an intra-assay coefficient of variation (CV) of 8.9% for sera with TSH levels of 1.5 ng/mL and 13.2% for sera with TSH levels of 17.5 ng/mL (n = 14). The inter-assay CV was 13.5% for sera with TSH levels of 1.4 ng/mL and 14.5% for TSH levels of 18.2 ng/mL (n = 5). The analysis of mean TSH levels in control rats (5.06 ± 0.5701) and hypothyroid rats (51.09 ± 5.136) revealed a statistically significant difference (p < 0.001) between the groups. This method showed good sensitivity, can be automated and is low-cost compared with RIA. Our method offers a viable alternative for TSH measurement in rats.

More than kin, less than kind: one family and the many faces of diabetes in youth.

Identification of the correct etiology of diabetes brings important implications for clinical management. In this report, we describe a case of a 4-year old asymptomatic girl with diabetes since age 2, along with several individuals in her family with different etiologies for hyperglycemia identified in youth. Genetic analyses were made by Sanger sequencing, laboratory measurements included HbA1c, lipid profile, fasting C-peptide, pancreatic auto-antibodies (glutamic acid decarboxylase [GAD], Islet Antigen 2 [IA-2], and anti-insulin). We found a Gly178Ala substitution in exon 5 of GCK gene in three individuals co-segregating with diabetes, and type 1 diabetes was identified in two other individuals based on clinical and laboratory data. One individual with previous gestational diabetes and other with prediabetes were also described. We discuss difficulties in defining etiology of hyperglycemia in youth in clinical practice, especially monogenic forms of diabetes, in spite of the availability of several genetic, laboratory, and clinical tools.