Basal and Stimulated Calcitonin and Procalcitonin by Various Assays in Patients with and without Medullary Thyroid Cancer

Insulinoma with Hyperprocalcitoninemia and Hypercalcitoninemia Showing Coexpression of Insulin and Calcitonin in Its Tumor Cells

Neuroendocrine neoplasms can produce multiple hormones that are released into the bloodstream, causing symptoms that vary depending on the type and quantity of hormones involved. We herein report a 63-year-old asymptomatic patient with pancreatic insulinoma who showed marked elevations in circulating calcitonin and procalcitonin levels that returned to normal following surgery. Immunohistochemical analyses confirmed the co-staining of calcitonin and insulin immunoreactivity in the tumor cells, suggesting a calcitonin-producing insulinoma. This insulinoma released calcitonin and a considerable amount of its precursor peptide, procalcitonin, resulting in both hyperprocalcitoninemia and hypercalcitoninemia.

Serum Biochemical Markers for Medullary Thyroid Carcinoma: An Update

Introduction

Medullary thyroid carcinoma (MTC), a rare malignancy, requires early diagnosis for optimal patient outcomes. An important aspect of MTC diagnosis is the assessment of serum biomarkers. This review aimed to evaluate the use of serum biomarkers in the diagnosis, prognosis, and follow-up of MTC.

Methods

A thorough search of PubMed covering 1975 to 2022 was conducted to identify English-language articles on MTC serum biomarkers.

Results

The review revealed that calcitonin (Ctn) and carcinoembryonic antigen (CEA) remain the most important serum biomarkers for MTC diagnosis and management. Despite limited studies on procalcitonin (PCT), its stability and ability to exclude interference from inflammation make it a valuable potential marker of MTC. Although the positive rate of serum CA19-9 levels in MTC patients was not high, it can be used as an indicator of poor prognosis in advanced MTC. Other serum markers, including chromogranin A, gastrin-releasing peptide precursor, and neurospecific enolase, did not show any unique value in MTC diagnosis and management.

Conclusion

Taken together, this review emphasized the importance of serum biomarkers, particularly Ctn and CEA, in the diagnosis and management of MTC. PCT shows promise as a valuable potential marker, whereas CA19-9 can be used as a prognostic indicator of advanced MTC. Further research is needed to validate the significance of these serum biomarkers in MTC and determine the effects of confounding factors on their levels. Clinicians should consider using these markers in MTC diagnosis, prognosis, and follow-up, particularly for patients with advanced disease.

Update on Calcitonin Screening for Medullary Thyroid Carcinoma and the Results of a Retrospective Analysis of 12,984 Patients with Thyroid Nodules

BACKGROUND

We provide an update on calcitonin (Ctn) screening for the early detection of medullary thyroid carcinoma (MTC) and present the results of a large single-center analysis evaluating sex-specific cut-off-levels and long-term courses.

METHODS

A total of 12,984 consecutive adult patients (20.1% male and 79.9% female) with thyroid nodules who had undergone routine Ctn measurement were retrospectively analyzed. Patients with confirmed suspicious Ctn values were referred for surgery.

RESULTS

Ctn measurements were elevated in 207 (1.6%) patients, with values below twice the sex-specific reference limit in 82% of these cases. Further clarification was possible in 124/207 cases, of which MTC could be ruled out in 108 cases. Histopathological assessment confirmed MTC in 16/12,984 patients.

CONCLUSIONS

Our extrapolated MTC prevalence of 0.14% is significantly lower than that described in early international screening studies. The stimulation test can usually be dispensable when using a decision-making concept based on sex-specific basal Ctn cut-off values. Ctn screening is recommended even in patients with very small thyroid nodules. High quality standards in pre-analytics, laboratory measurements, and the interpretation of data must be ensured, as well as close interdisciplinary cooperation between medical disciplines.

Evolution of thyroid cancer biomarkers: from laboratory test to patients’ clinical management

Over the past three decades, laboratory medicine has significantly evolved thanks to technological advances made possible by new materials and evidence. Clinicians’ ongoing requests for powerful, rapid, and minimally invasive tests has led manufacturers to develop rapid, accurate, and sensitive tests that can increase diagnostic accuracy and improve follow-up, bringing laboratory medicine ever closer to personalized medicine. The aim of this study was to critically review the main problems of the current Tg and CT biomarkers for the diagnosis/monitoring of DTC and MTC, respectively, and to identify the advantages and challenges of using the new laboratory biomarkers in the clinical management of patients with differentiated and medullary thyroid cancer. Insufficient harmonization of Tg and CT assays and lack of interchangeability of laboratory results and cutoff values pose challenges for comparability and standardization of procedures and methods. New diagnostic and monitoring approaches such as PCT or the Tg doubling time have proven to be effective. Close collaboration between clinicians and laboratory specialists remains essential to translate the advantages and limitations of current assays into appropriate clinical interpretation criteria. Over the years, the journal Clinical Chemistry and Laboratory Medicine (CCLM) has taken many steps to develop advanced research and technology in the diagnosis and monitoring of tumor cancer and to help clinicians translate it into clinical practice.

Analytical Performance Evaluation of a New Calcitonin Assay

BACKGROUND

The use of efficient laboratory calcitonin (CT) testing is required for optimal management of medullary thyroid carcinoma. Several pitfalls are related to the calcitonin laboratory assays and a careful evaluation is needed. We report the analytical performances of the new Siemens ADVIA-Centaur-CALCT (CT-XPT) assay and its comparison with our standard method DiaSorin-Calcitonin-II-Gen (CT-LIA) assay.

METHODS

Analytical performance of the CT-XPT-assay, limit of blank (LOB), limit of detection (LOD), and limit of quantification (LOQ), were determined. We also evaluated the in vitro stability of the sample, together with the linearity and percentage recovery.

RESULTS

The CT-XPT-assay showed a better detection limit than the CT-LIA assay, with lower values of LOB (0.86 pg/mL vs 1.00 pg/mL) and LOQ (1.65 pg/mL vs 3.00 pg/mL). Both values were in agreement with those reported by the manufacturer. Within- and between-run precision demonstrated a good concordance of results. Regarding the in vitro stability of CT, the low CT concentration sera showed a much greater decrease in CT levels compared to the high concentration sera. Correlation studies showed a good correlation between the two methods (Kappa Cohen coefficent, KC: 0.68, agreement % for male: 89.58%; KC: 0.63; agreement % for female: 88.33%).

CONCLUSIONS

Our findings showed a good correlation between the CT-LIA and CT-XPT methods. Moreover, we demonstrated that the analytical performance of the CT-XPT assay, together with its technical specifications, could represent major features of the CT-XPT method. Collectively, the technical evaluation and the analytical results described in the presented paper highlight that the novel CT-XPT is a valid method for CT testing in a clinical diagnostic setting.

Calcitonin: current concepts and differential diagnosis

Calcitonin (CT) is most effectively produced by the parafollicular cells of the thyroid gland. It acts through the calcitonin receptor (CTR), a seven-transmembrane class II G-protein-coupled receptor linked to multiple signal transduction pathways with its main secretagogues being calcium and gastrin. It is clinically used mostly in the diagnosis and follow-up of medullary thyroid carcinoma (MTC). Hypercalcitoninemia can be attributed to primary (e.g. CT-secreting tumor) or secondary (e.g. due to hypercalcemia) overproduction, underexcretion (e.g. renal insufficiency), drug reaction (e.g. β-blockers), or false-positive results. In clinical practice, elevated basal calcitonin (bCT) is indicative, but not pathognomonic, of MTC. Current literature leans toward an age as well as gender-specific cutoff approach. bCT >100 pg/ml has up to 100% positive prognostic value (PPV) for MTC, whereas bCT between 8 and 100 pg/ml for adult males and 6 and 80 pg/ml for adult females should be possibly further investigated with stimulation calcitonin (sCT) tests. Calcium is showing similar efficacy with pentagastrin (Pg) sCT; however, the real value of these provocative tests has been disputed given the availability of new, highly sensitive CT immunoassays. Anyhow, evidence concludes that sCT <2 times bCT may not be suggestive of MTC, in which case, thyroid in addition to whole body workup based on clinical evaluation is further warranted. Moreover, measurement of basal and stimulated procalcitonin has been proposed as an emerging concept in this clinical scenario. Measuring bCT levels in patients with thyroid nodules as a screening tool for MTC remains another controversial topic. It has been well established, though, that bCT levels raise the sensitivity of FNAB (Fine Needle Aspiration Biopsy) and correlate with disease progression both pre- and postoperatively in this situation. There have been numerous reports about extrathyroidal neoplasms that express CT. Pancreatic, laryngeal, and lung neuroendocrine neoplasms (NENs) are most frequently associated with hypercalcitoninemia, but CT production has also been described in various other neoplasms such as duodenal, esophageal, cutaneous, and paranasal NENs as well as prostate, colon, breast, and lung non-NENs. This review outlines the current biosynthetic and physiology concepts about CT and presents up-to-date information regarding the differential diagnosis of its elevation in various clinical situations.

Calcitonin and complementary biomarkers in the diagnosis of hereditary medullary thyroid carcinoma in children and adolescents

OBJECTIVES

Medullary thyroid carcinoma (MTC) is a rare malignancy that is effectively curable by surgery. Unlike in adults, hereditary MTC has a predominant role in children. A fast and safe diagnosis is important to assure the good prognosis for the patients. A major cornerstone is the assessment of biomarkers, but the interpretation must respect their pre-, post- and analytical features. Especially calcitonin (Ctn) is a challenging biomarker in daily laboratory diagnostics. However, Ctn is of particular relevance for the diagnostic in MTC. The American Thyroid Association recommends thyroidectomy if the upper reference range of Ctn is exceeded. Interestingly, age-dependent reference ranges for children and adolescents have become available only recently for Ctn assays. With this review, we aim to highlight the importance of a timely diagnosis of MTC in children and adolescents.

CONTENT

Recent developments in pediatric biochemical diagnostics of MTC were summarized. This includes guidance on interpretation of RET, Ctn, procalcitonin, carcinoembryonic antigen, carbohydrate antigen 19-9, and chromogranin A.

SUMMARY

Currently, Ctn is the most investigated biomarker in the diagnosis of MTC in children and adolescents. Other biomarkers as PCT suggest complementary evidence about pediatric MTC but their interpretation based largely on adult's data. A successful treatment of MTC requires, besides results of biomarkers, information about medical history, RET gene analysis and recent guideline knowledge.

OUTLOOK

More research is required to validate complementary biomarkers of Ctn in children. Additionally, the effect of different confounder on pediatric Ctn levels has to be further clarified.

Procalcitonin as an Alternative Tumor Marker of Medullary Thyroid Carcinoma

CONTEXT

Calcitonin (CT) measurement is pivotal in the management of medullary thyroid carcinoma (MTC), but several pitfalls can affect its reliability. Procalcitonin (ProCT) has been reported as a promising alternative MTC tumor marker.

OBJECTIVE

This study aimed to determine the ProCT diagnostic accuracy in prediction and treatment monitoring of MTC.

METHODS

Electronic databases were searched for observational studies published until May 2021 without language or time restrictions. Studies comparing ProCT and calcitonin accuracy were included. After removing duplicates and exclusion of not-eligible articles, relevant articles were screened independently by 2 reviewers. Eleven studies (4.5% of the identified studies) met the selection criteria. Two reviewers independently extracted data and assessed data quality and validity through QUADAS-2.

RESULTS

A meta-analysis was performed on 11 sufficiently clinically and statistically homogeneous studies (n = 5817 patients, 335 MTC patients). Hierarchical summary receiver operating characteristics and bivariate methods were applied. Serum ProCT was found to be a highly accurate test for MTC diagnosis and monitoring. The pooled sensitivity, specificity, positive and negative likelihood ratios, area under the curve, and positive and negative predictive values for ProCT were 0.90 (95% CI: 0.71-0.97), 1.00 (95% CI: 0.85-1.00), 288 (95% CI: 5.6-14 929.3), 0.10 (95% CI: 0.03-0.33), 0.97 (95% CI: 0.95-0.98), 99%, and 2%, respectively.

CONCLUSIONS

The high accuracy, compounded with favorable analytical characteristics, give ProCT great potential to replace calcitonin as a new standard of care in the management of MTC.

Correction factor between two calcitonin assays: DiaSorin LiaisonXL and Cobas E601

Introduction: Calcitonin measurement is important for the diagnosis and monitoring of medullary thyroid carcinoma. Unfortunately, in clinical practice, different detection systems assays are used in the follow-up of the patients, which can be misleading.

Objective: To identify the correction factor for calcitonin measurement on two different immunoanalysers: DiaSorin-LiaisonXL (immunochemiluminescence) and CobasE601 (electro-immunochemiluminescence).

Methods: We selected 89 registered CT samples (28-from men; 61-from women), that were analysed on CobasE601 with reported values between 0.5 pg/ml and 2812 pg/ml (128.5±513.98). These CT samples were selected randomly to cover as wide a range of values as possible, and represented either basal CT (n=38) or selected from CT stimulation tests (n=51). Samples were evaluated subsequently on DiaSorin-LiaisonXL. All patients gave their informed consent.

Results: Between the two assays a segmented linear correlation was noted. We identified the following general linear regression equation: 1.108x+19.337 (p<0.05). The bias increased at high calcitonin values. Therefore, for a better accuracy we analysed the regression equation segmentally. A statistic difference (p<0.05) was noted for CT values ranged between 350-2600 pg/ml (n=31) on DiaSorin-LiaisonXL, for which the linear regression equation for CobasE601 becomes 1.009x+169.796.

Conclusions: Calcitonin correction factors are highly important in the dynamic follow up of a patient suffering from medullary thyroid carcinoma when different detection systems assays are used to determine calcitonin. We identified the correction factors for calcitonin determination between two different frequently used chemiluminescence immunoanalysers: DiaSorin-LiaisonXL and CobasE601. However, it is strongly advisable to use the same analyser in order to establish biochemical evolution of calcitonin.

Procalcitonin measured by three different assays is an excellent tumor marker for the follow-up of patients with medullary thyroid carcinoma

OBJECTIVES

Procalcitonin (PCT) has been suggested as a tumor marker in patients with medullary thyroid carcinoma (MTC). Clinical application data in long term follow-up are missing.

METHODS

210 serum samples of 169 consecutive patients with MTC (92 sporadic, 77 hereditary, 158 postoperative follow-up, 11 preoperative) were collected between 2018 and 2020. Postoperative patients were stratified into three groups according to their disease status at the end of follow-up: cured (n=51, calcitonin (CT) levels < limit of quantitation), minimal residual disease (n=55, detectable CT and no metastases provable by imaging methods), metastatic disease (n=52). In five patients CT and PCT were measured while on therapy with tyrosine kinase inhibitors (TKI). CT was analyzed by the Roche ECLIA, PCT by three assays from Roche, PES, Abbott.

RESULTS

The mean ± SD values seen with the three PCT assays in the MTC response groups, cured: <0.06, 0.016 ± 0.007, 0.014 ± 0.007 ng/mL, minimal residual disease: 0.511 ± 0.800, 0.389 ± 0.687, 0.341 ± 0.614 ng/mL, metastatic disease 109 ± 202, 60.4 ± 110, 63.3 ± 115 ng/mL correlate well with the CT results in these groups: cured <1.0 pg/mL, minimal residual disease 91.3 ± 121.5 pg/mL, metastatic disease 14,489 ± 30,772 pg/mL. There was a significant correlation (p<0.001) between the three PCT assays (Roche/PES r=0.970, Roche/Abbott r=0.976, Abbott/PES r=0.995). In the course of treatment with TKI both CT and PCT reflected clinical state. Preoperative PCT in hereditary MTC has the same diagnostic validity than CT.

CONCLUSIONS

PCT measured with three different immunoassays is as good as the standard tumor marker CT in the follow-up of MTC but has a superior analytical stability.

Basal and pentagastrin-stimulated calcitonin cut-off values in diagnosis of preoperative medullary thyroid cancer

Background/aim

Medullary thyroid cancer (MTC) originates from parafollicular cells (C cell) and produces calcitonin (CT). Basal serum CT was used in the diagnosis and treatment of MTC. If basal CT level is 100 pg/mL or higher, it is likely to have MTC, but if basal CT level is below 10 pg/mL, the probability of developing thyroid disease is low. In cases with basal CT level between 10–100 pg/mL, pentagastrin-stimulated (PS) CT level is studied to evaluate MTC and C cell hyperplasia (CHH). This study aimed to determine cut-off value for basal and PS peak CT level for diagnosis of MTC.

Materials and methods

We retrospectively reviewed files of patients presented to endocrine outpatient clinic of Ege University, Medicine School, between 2010 and 2019; 176 patients with basal CT level of 10–100 pg/mL and patients with PS test were included to the study.

Results

The receiver operating characteristic curve (ROC) analysis was used to determine cut-off value for basal CT that can discriminate cases with MTC and those with nodular goiter. Cut-off value for basal CT was calculated as 46.5 pg/mL (specificity; 100 %, sensitivity; 74 %). In the ROC analysis for peak PS CT, cut-off value was calculated as 285 pg/mL (specificity:100 %; sensitivity:82 %). When peak CT level was > 290 pg/mL in PS test, both specificity and sensitivity for MTC were determined as 100 %. The PS peak CT level > 285 pg/mL was significant for MTC diagnosis while range of 117–274 pg/mL was significant for CHH.

Conclusion

In this study, cut-off value was calculated as 46.5 pg/mL for basal CT, whereas 285 pg/mL for PS peak CT in the diagnosis of preoperative MTC.

Diagnostic Challenges of Medullary Thyroid Carcinoma

BACKGROUND

Medullary thyroid carcinoma (MTC) comprises 1-2% of all thyroid cancers, yet 15% of all thyroid cancer-related deaths. While up to 20% of cases may be predicted due to autosomal dominant germline mutations, 80% of cases are sporadic. However, due to non-specific presenting symptoms and diagnostic imaging, prompt diagnosis and treatment has remained elusive. This article will further investigate the limitations of MTC diagnosis and look into future areas for diagnostic improvement.

METHODS

Relevant articles were identified using a systematic PubMed and Google Scholar search.

RESULTS

Prophylactic total thyroidectomy for the 20% of MTC cases that are present in autosomal dominant disorder provides definitive treatment. Serum calcitonin (Ctn) screening has several technical limitations due to population variability and laboratory assay interference, but advances in laboratory technology and combined use with fine needle aspiration increase its sensitivity. Other serum assays such as carcinoembryonic antigen and procalcitonin have limited applicability. Thyroid ultrasound remains the gold standard for the initial diagnostic planning, with limited application for CT, MRI, and PET imaging.

CONCLUSION

With complete surgical resection the only definitive treatment, early MTC diagnosis has presented an elusive challenge, mainly due to its relative rarity and difficulty in finding an economic screening strategy. Careful family history combined with fine needle aspiration with serum Ctn analysis can improve diagnostic sensitivity and specificity to greater than 95%.

Improving Science by Overcoming Laboratory Pitfalls With Hormone Measurements

Despite all the effort taken, there is often surprisingly little attention paid to the hormone analyses involved in research studies. Thinking carefully about the quality of the hormone measurements in these studies is, however, of major importance, as this attention to methods may prevent false conclusions and inappropriate follow-up studies. We discuss issues regarding hormone measurements that one should consider, ideally prior to starting, or otherwise, as they arise during a scientific study: quality of the technique, expertise, matrices, timing and storage conditions, freeze-thaw cycles, lot-to-lot and day-to-day variation, analyses per batch or sample-wise, singlicate or duplicate measurements, combining methods, and standardization. This article and the examples mentioned herein aim to clarify the need to pay attention to the hormone analyses, and to help in making decisions. In addition, these examples help editors and reviewers of scientific journals to pay attention to the methods section in the submitted manuscripts and ask the right critical questions when needed.

Diagnostic accuracy of routine calcitonin measurement for the detection of medullary thyroid carcinoma in the management of patients with nodular thyroid disease: a meta-analysis

OBJECTIVE

The usefulness of routine calcitonin measurement for early detection of medullary thyroid carcinoma (MTC) in patients with nodular thyroid disease (NTD) has been investigated in various studies. Recently, a Cochrane review has been published on this issue, but a meta-analysis is lacking yet. Therefore, we performed this meta-analysis.

METHODS

We performed an electronic search using PubMed/Medline, Embase and the Cochrane Library. Studies assessing the diagnostic accuracy of routine calcitonin measurement for detecting MTC in patients with NDT were selected. Statistics were performed by using Stata software, risk of bias was assessed using Review Manager version 5.3.

RESULTS

Seventeen studies, involving 74,407 patients were included in the study. Meta-analysis, using the bivariate random effects model and the hierarchical summary receiver operating characteristic (HSROC) curve revealed the following pooled estimates: sensitivity 0.99 (95% CI, 0.81-1.00), specificity 0.99 (95% CI, 0.97-0.99), positive likelihood ratio (L+) 72.4 (95% CI, 32.3-162.1), and negative likelihood ratio (L-) 0.01 (95% CI, 0.00-0.23). Meta-regression analysis showed that the threshold of basal calcitonin is an independent factor, but in particular performing stimulation test is not an independent factor.

CONCLUSIONS

We showed that routine basal serum calcitonin measurement in the management of patients with thyroid nodules is valuable for the detection of MTC. However, the published cut-off values should be considered and, if applicable, the patients monitored in a wait-and-see strategy by experienced physicians to avoid overtreatment.

Basal and Calcium-Stimulated Procalcitonin for the Diagnosis of Medullary Thyroid Cancers: Lights and Shadows

BACKGROUND

Procalcitonin (proCt) was recently proposed as an alternative or in addition to calcitonin (Ct) in medullary thyroid cancer (MTC) diagnostics.

METHODS

Serum basal Ct (bCt) and proCt (bproCt) levels were measured before surgery from a consecutive series of patients with (n=43) and without (n=75) MTC, retrospectively collected in Padua. Serum bproCt, bCt and stimulated proCt and Ct (sproCt and sCt) were measured in another consecutive series of 33 patients seen at three tertiary-level institutions undergoing a calcium stimulation test prior to surgery, 20 of them with a final diagnosis of MTC, and 13 with non-MTC nodular disease.

RESULTS

Median bproCt levels were higher in MTC than in non-MTC. A positive correlation was found for bproCt with bCt (P<0.01, R² = 0.75), and with tumor size (P<0.01, R² = 0.39). The cut-off for bproCt differentiating between MTC and non-MTC patients was >0.07 ng/ml (sensitivity: 85.7%, specificity: 98.9%, positive predictive value [PPV]: 98.2%, negative predictive value [NPV]: 90.6%, P<0.01). While bproCt was >0.07 ng/ml in 38/39 (97.4%) patients with MTC >10 mm, it was above said cut-off only in 15/23 (65.2%) patients with tumors ≤10 mm. A sproCt >0.19 ng/ml was able to identify MTC [sensitivity: 90.0%, specificity:100.0%, PPV: 100.0%, NPV: 86.7% (P<0.01)].

CONCLUSIONS

Our data suggest that bproCt can be a good adjunct to Ct for MTC diagnostic purposes. In consideration of its high specificity, it can be used in combination with Ct in MTC diagnostics, particularly in the case of mildly elevated basal Ct levels.

Clinical performance of calcitonin and procalcitonin Elecsys® immunoassays in patients with medullary thyroid carcinoma

Objectives

Medullary thyroid carcinoma (MTC) is caused by a malignant transformation in the parafollicular C-cells of the thyroid, where calcitonin (CT) is released. Nowadays, CT is the main tumor marker used in the diagnosis and follow-up of MTC patients. Nonetheless, procalcitonin (PCT) has recently been proposed as a useful complementary/alternative biomarker in MTC. Our aims were to investigate the diagnostic performance of CT and PCT and their combination in the differential diagnosis between active and inactive MTC and between MTC and non-MTC thyroid diseases, respectively.

Methods

Serum samples were collected from 16 patients with active (i.e. primary tumour before surgery or post-surgical recurrent disease) and 23 with inactive (i.e. complete remission) MTC, 125 patients with non-MTC benign thyroid disease and 62 patients with non-MTC thyroid cancers, respectively. Elecsys® CT and PCT measurements were simultaneously performed on the Cobas e601 platform (Roche Diagnostics, Rotkreutz, Switzerland).

Results

Both CT and PCT median values in active MTC (94 pmol/L and 1.17 ng/mL, respectively) were significantly higher compared with inactive MTC (0.28 and 0.06) and either benign (0.37 and 0.06) or malignant (0.28 and 0.06) non-MTC. Undetectable PCT was found in five non-MTC patients with false positive CT results.

Conclusions

Elecsys® PCT assay is a highly sensitive and specific alternative MTC marker. At the very least it appears useful in patients with positive CT results as negative PCT values securely exclude active MTC. The availability of both markers on the same automated platform facilitates reflex or reflective strategies to refine the laboratory diagnosis.

Calcitonin levels by ECLIA correlate well with RIA values in higher range but are affected by sex, TgAb, and renal function in lower range

Calcitonin (CT) is a marker for both initial diagnosis and monitoring of patients with residual or recurrent medullary thyroid carcinoma (MTC). In Japan, serum CT had been measured by radioimmunoassay (RIA) until recently. Electrochemiluminescence immunoassay (ECLIA) became commercially available in 2014, and this technique is now the only method used to examine CT concentration. The purposes of this study were to investigate the correlations between the CT concentration measured with ECLIA (ECLIA-CT) and RIA (RIA-CT) and to explore the clinical characteristics of patients with elevated ECLIA-CT. CT concentrations of 348 sera samples from 334 patients with various thyroid disorders including nine MTC were measured using both assays. The correlation analysis revealed an excellent correlation between ECLIA-CT and RIA-CT among the cases with CT level >150 pg/mL by both assays (r_s = 0.991, p < 0.001). However, 63% of all samples exhibited undetectable ECLIA-CT, while their RIA-CTs were measured between 15 and 152 pg/mL. The ECLIA-CTs in all patients who underwent total thyroidectomy for non-MTC showed low concentrations. High ECLIA-CT was observed in patients with MTC or pancreas neuroendocrine tumor. ECLIA-CT was also increased in 14 other male patients with non-MTC, including four with renal failure. Multivariate logistic regression analysis showed that male sex, negative TgAb, and lower estimated glomerular filtration rate were independent factors to predict detectable ECLIA-CT (≥0.500 pg/mL). These results indicate that ECLIA-CT correlates well with RIA-CT in higher range and is affected by sex, TgAb, and renal function.

[Medullary thyroid carcinoma and multiple endocrine neoplasia type 2]

Medullary thyroid carcinoma (MTC) is a rare malignancy and compromises only 3 % of all thyroid carcinomas. MTC cells secret calcitonin, which serves as a sensitive tumor marker for screening and follow-up of MTC. Calcitonin screening in patients with nodular goiter allows for early diagnosis of MTC and surgical curative treatment. In 25 % of patients MTC occurs as an integral part of multiple endocrine neoplasia type 2 (MEN2), an autosomal dominant inherited tumor syndrome. It is caused by germline mutations in the RET protooncogene. In gene carriers early diagnosis and treatment through prophylactic thyroidectomy is possible. MTC is a slowly growing tumor with a good prognosis and 5 and 10 year survival rates up to 80 and 60 %. In the follow-up a dynamic risk stratification allows for a personalized disease management. In symptomatic and progressive metastasizing MTC tyrosine kinase inhibitors are an effective therapy.

Calcitonin measurement in pediatrics: reference ranges are gender-dependent, validation in medullary thyroid cancer and thyroid diseases

BACKGROUND

There is only limited information on serum reference ranges of calcitonin (CT) in infants, children and adolescents. This gap hampers valid diagnostics in patients with multiple endocrine neoplasia type 2 (MEN 2) and planned prophylactic thyroidectomy. In addition, age-dependent reference ranges for CT are necessary to define a cure in medullary thyroid carcinoma (MTC). We asked whether the reference ranges for CT levels were age- and gender-dependent in the serum of a pediatric cohort.

METHODS

A total of 6090 serum samples of 2639 subjects of the LIFE-Child cohort aged between 1 month and 17.9 years were analyzed by the CT electrochemiluminescence immunoassay (ECLIA). Reference intervals were estimated using the LMS method. For clinical validation the serum of 28 patients (61 samples) with MEN 2 and 106 patients (136 samples) with thyroid diseases were analyzed.

RESULTS

CT levels showed a clear age- and gender-dependence with significantly higher values in boys (p<0.01). An accelerated decline of CT levels from newborn to children at the age of 4 and 5 years was observed for both sexes. A cure for MTC was demonstrated in 71% of MEN 2 patients after thyroidectomy, whereas 5 patients remained suspicious for micrometastasis or relapse. Only 1.5% of our patients with thyroid diseases revealed increased CT levels.

CONCLUSIONS

This is the largest study to establish novel pediatric reference ranges from the CT values of healthy subjects. It allows a precise laboratory monitoring of CT in pediatric patients with MEN 2. Thyroid diseases did not have a relevant influence on CT levels in our pediatric cohort.

Calcitonin testing for detection of medullary thyroid cancer in people with thyroid nodules

BACKGROUND

Thyroid nodules are very common in general medical practice, but rarely turn out to be a medullary thyroid carcinoma (MTC). Calcitonin is a sensitive tumour marker for the detection of MTC (basal calcitonin). Sometimes a stimulation test is used to improve specificity (stimulated calcitonin). Although the European Thyroid Association's guideline advocates calcitonin determination in people with thyroid nodules, the role of routine calcitonin testing in individuals with thyroid nodules is still questionable.

OBJECTIVES

The objective of this review was to determine the diagnostic accuracy of basal and/or stimulated calcitonin as a triage or add-on test for detection of MTC in people with thyroid nodules.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and Web of Science from inception to June 2018.

SELECTION CRITERIA

We included all retrospective and prospective cohort studies in which all participants with thyroid nodules had undergone determination of basal calcitonin levels (and stimulated calcitonin, if performed).

DATA COLLECTION AND ANALYSIS

Two review authors independently scanned all retrieved records. We extracted data using a standard data extraction form. We assessed risk of bias and applicability using the QUADAS-2 tool. Using the hierarchical summary receiver operating characteristic (HSROC) model, we estimated summary curves across different thresholds and also obtained summary estimates of sensitivity and specificity at a common threshold when possible.

MAIN RESULTS

In 16 studies, we identified 72,368 participants with nodular thyroid disease in whom routinely calcitonin testing was performed. All included studies performed the calcitonin test as a triage test. Median prevalence of MTC was 0.32%. Sensitivity in these studies ranged between 83% and 100% and specificity ranged between 94% and 100%. An important limitation in 15 of the 16 studies (94%) was the absence of adequate reference standards and follow-up in calcitonin-negative participants. This resulted in a high risk of bias with regard to flow and timing in the methodological quality assessment. At the median specificity of 96.6% from the included studies, the estimated sensitivity (95% confidence interval (CI)) from the summary curve was 99.7% ( 68.8% to 100%). For the median prevalence of MTC of 0.23%, the positive predictive value (PPV) for basal calcitonin testing at a threshold of 10 pg/mL was 7.7% (4.9% to 12.1%). Summary estimates of sensitivity and specificity for the threshold of 10 pg/mL of basal calcitonin testing was 100% (95% CI 99.7 to 100) and 97.2% (95% CI 95.9 to 98.6), respectively. For combined basal and stimulated calcitonin testing, sensitivity ranged between 82% and 100% with specificity between 99% and 100%. The median specificity was 99.8% with an estimated sensitivity of 98.8% (95% CI 65.8 to 100) .

AUTHORS' CONCLUSIONS

Both basal and combined basal and stimulated calcitonin testing have a high sensitivity and specificity. However, this may be an overestimation due to high risk of bias in the use and choice of reference standard The value of routine testing in patients with thyroid nodules remains questionable, due to the low prevalence, which results in a low PPV of basal calcitonin testing. Whether routine calcitonin testing improves prognosis in MTC patients remains unclear.

Combining procalcitonin with the qSOFA and sepsis mortality prediction

To investigate whether procalcitonin (PCT) can improve the performance of quick sequential organ failure assessment (SOFA) score in predicting sepsis mortality, we conducted a retrospective multicenter cohort study with independent validation in a prospectively collected cohort in 3 tertiary medical centers. Patients with presumed sepsis were included. Serum PCT levels were measured at admission. Quick SOFA score and systemic inflammatory response syndrome (SIRS) criteria were calculated for each patient. PCT levels were assigned into 0, 1, and 2 points for a serum level of <0.25, 0.25 to 2, and >2 ng/mL, and added to the quick sepsis-related organ failure assessment (qSOFA) score. The incremental value of PCT to qSOFA was then evaluated by logistic regression, receiver-operating characteristic (ROC) curve, and reclassification analysis.In all, 1318 patients with presumed severe infection were enrolled with a 30-day mortality of 13.5%. Serum level of PCT showed a high correlation with qSOFA score and 30-day inhospital mortality. The area under the ROC curve was 0.56 for SIRS criteria, 0.67 for qSOFA score, and 0.73 for qSOFA_PCT in predicting 30-day mortality. The risk prediction improvement was reflected by a net reclassification improvement of 35% (17%-52%). Incorporation of PCT into the qSOFA model could raise the sensitivity to 86.5% (95% confidence interval 80.6%-91.2%). In the validation cohort, qSOFA_PCT greatly improved the sensitivity to 90.9%.A simple modification of qSOFA score by adding the ordinal scale of PCT value to qSOFA could greatly improve the suboptimal sensitivity problem of qSOFA and may serve as a quick screening tool for early identification of sepsis.

Calcium-stimulated calcitonin - The "new standard" in the diagnosis of thyroid C-cell disease - clinically relevant gender-specific cut-off levels for an "old test"

Introduction

Pentagastrin (Pg) stimulated calcitonin (sCT) was used to enhance accuracy in medullary thyroid cancer (MTC) diagnosis. As it is now unavailable, calcium (Ca) has been recommended as an alternative. The aim of this study was to define gender-specific cut-off values to predict MTC in patients with elevated basal CT (bCT) following Pg-sCT and Ca-sCT stimulation and to compare the time courses of CT release during stimulation.

Materials and methods

The stimulation tests were applied in 62 consecutive patients with thyroid nodules. Basal calcitonin was measured by chemiluminescent immunometric assay. All patients underwent thyroidectomy and bilateral central neck dissection. C-cell pathology was confirmed by histological and immunohistochemical evaluation.

Results

In 39 (0.63) patients MTC was documented while isolated C-cell hyperplasia (CCH) was identified in 23 (0.37) patients. Medullary thyroid cancer was predicted in males with bCT values > 43 pg/mL or sCT concentrations > 470 pg/mL (Pg-sCT) or > 1500 pg/mL (Ca-sCT), and in females with bCT concentrations > 23 pg/mL or sCT concentrations > 200 pg/mL (Pg-sCT) or > 780 pg/mL (Ca-sCT), respectively. Pg-sCT correctly predicted MTC in 16 (0.66) compared to 13 (0.54) after Ca-sCT in males and in 12 (0.80) compared to 11 (0.73) in females; without statistical significance. In patients with CCH or low tumor burden, there was a tendency of faster CT release after Ca stimulation (CT peak after 3min in > 60%) compared to patients with advanced MTC (CT peak after 3min in < 10%).

Conclusions

Using gender-specific cut-off values, Ca could replace Pg to predict MTC with similar diagnostic power.

Update on Multiple Endocrine Neoplasia Type 2: Focus on Medullary Thyroid Carcinoma

Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant hereditary cancer syndrome caused by missense gain-of-function mutations in the RET proto-oncogene on chromosome 10. Specific RET mutations can predispose toward a particular phenotype and clinical course, with strong genotype–phenotype correlations. MEN2 is highly penetrant in medullary thyroid carcinoma (MTC), and it can be associated with bilateral pheochromocytoma and primary hyperparathyroidism. Two different clinical variants of MEN2 are known: MEN2A, which includes the familial subtype, and MEN2B. Treatment includes early thyroidectomy. Recommendations on the timing and extent of surgery are based on the RET mutation risk categories (moderate-, high-, or highest-risk) regarding the age of MTC onset. Early identification of patients with hereditary MTC has improved treatment outcomes. Previously, MTC was diagnosed based on clinical tumors; in contrast, with genetic screening, MTC can be diagnosed at preclinical disease states. This approach has resulted in a high cure rate and a much better prognosis for MTC. However, classification into one of the three RET mutation risk groups for predicting aggressiveness and prognosis has had limited impact. Increasing evidence has shown that patients with RET mutations in different risk classifications exhibit a broad spectrum of MTC aggressiveness during follow-up, with no relevant difference in survival. The specific germline activating mutation of the RET proto-oncogene appears to be the first determinant of the age of MTC onset, but, presumably, different regulatory events determine long-term tumor behavior.

Procalcitonin measurement to screen medullary thyroid carcinoma: A prospective evaluation in a series of 2705 patients with thyroid nodules

BACKGROUND

To prospectively evaluate the role of procalcitonin (PCT) in screening of patients with thyroid nodules for medullary thyroid carcinoma (MTC).

MATERIALS AND METHODS

We measured PCT in 2705 patients with thyroid nodules referred to our centre between January 2011 and December 2017. Those with a positive PCT were operated after positive confirmatory tests such as fine-needle aspiration, measurement of calcitonin (CT) in serum and fine-needle aspiration washouts or CT stimulation testing. Patients with a negative PCT were operated based on the results of further diagnostics. The diagnostic performance of PCT was evaluated, and the best cut-off level was selected by ROC curve analysis.

RESULTS

Among 2705 patients, 9 with positive serum PCT (ie, above 0.1 μg/L) and 370 with negative PCT underwent thyroid surgery. MTC was histologically confirmed in all patients with positive PCT but not found in patients with negative PCT. Serum PCT levels were significantly higher in patients with MTC (median 0.64 μg/L, range 0.16-12.9 μg/L) than in those without (median 0.075 μg/L, range 0.075-0.16 μg/L; P < .0001). ROC curves were plotted to calculate the optimal PCT value separating patients with MTC from those without. The best cut-off was 0.155 μg/L with sensitivity, specificity, positive and negative predictive values as well as accuracy of 100%, 99.7%, 91.7%, 100% and 99.7%, respectively. Positive and negative likelihood ratios were 329 and zero, respectively.

CONCLUSIONS

Measurement of PCT is a sensitive and accurate method for detecting MTC in patients with thyroid nodules and can thus be a reliable alternative to CT measurement.

Procalcitonin as Marker of Recurrent Medullary Thyroid Carcinoma: A Systematic Review and Meta-Analysis

BACKGROUND

Calcitonin measurement is pivotal in the management of medullary thyroid carcinoma (MTC), but several pitfalls can affect its reliability. Other potential markers have been proposed, and procalcitonin (ProCT) has been reported as promising. The present study was undertaken to summarize the published data and provide more robust estimates on the reliability of ProCT as marker in the management of patients with MTC.

METHODS

The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The sources comprised studies published through May 2018. Journal Articles that reported series of MTC patients undergone ProCT during postoperative follow-up were searched. A random-effects model was used for statistical pooling of the data. The I² index was used to quantify the consistency among the studies. The Egger test evaluated the possible presence of significant publication bias. Quality assessment of the studies was performed according to Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2).

RESULTS

According to inclusion and exclusion criteria five papers, reporting 296 MTC patients undergone ProCT evaluation, were finally selected. The number of MTC with recurrence was 140. The pooled sensitivity of ProCT in detecting recurrence was 96% (95% confidence interval [CI], 92% to 99%), with neither heterogeneity (I²=0%) nor publication bias (Egger test, 3.16; P=0.99). The pooled specificity was 96% (95% CI, 87% to 100%) with mild heterogeneity (I²=66.6%), while Egger test was not calculable.

CONCLUSION

The present meta-analysis provides evidence that ProCT is reliable to manage MTC patients during their postoperative follow-up.

Procalcitonin as a postoperative marker in the follow-up of patients affected by medullary thyroid carcinoma

AIM

Due to the limits of calcitonin, other markers are warranted to better manage medullary thyroid carcinoma patients, and procalcitonin has been reported as promising. Here we aimed to evaluate procalcitonin as a marker of medullary thyroid carcinoma in the post-treatment follow-up.

METHODS

Medullary thyroid carcinoma patients previously treated by thyroidectomy were enrolled. After complete imaging work-up (i.e. ultrasonography, computed tomography, magnetic resonance and ¹⁸FDG-PET-CT) we identified patients with structural recurrent/persistent medullary thyroid carcinoma (active medullary thyroid carcinoma) and subjects with no evidence of disease. Then, both calcitonin and procalcitonin were measured and their performance analyzed.

RESULTS

The final series included 55 medullary thyroid carcinoma patients treated and followed-up for about five years. Of these, 43 were assessed as no evidence of disease, and 12 as active medullary thyroid carcinoma. The median value of procalcitonin was significantly higher ( P < 0.0001) in active medullary thyroid carcinoma patients (3.10 ng/mL) than in those with no evidence of disease (0.10 ng/mL). Also, calcitonin levels of active medullary thyroid carcinoma (96.7 pg/mL) were significantly ( P < 0.0001) higher than that of no evidence of disease (2.0 pg/mL). At the receiver operating characteristic curve analysis, the optimal cut-off of procalcitonin was ≥0.32 ng/mL with 92% sensitivity and 98% specificity, while the most accurate threshold of calcitonin was ≥12.0 pg/mL with 100% sensitivity and 91% specificity. There was no active medullary thyroid carcinoma with simultaneously negative results of procalcitonin and calcitonin.

CONCLUSIONS

Procalcitonin is reliable in discriminating medullary thyroid carcinoma patients with active disease from those with no evidence of disease. We suggest using procalcitonin as complementary to calcitonin to follow-up medullary thyroid carcinoma patients.

Calcitonin Response to Naturally Occurring Ionized Hypercalcemia in Cats with Chronic Kidney Disease

Background

Hypercalcemia is commonly associated with chronic kidney disease (CKD) in cats.

Objectives

To explore the calcitonin response to naturally occurring ionized hypercalcemia in cats with azotemic CKD, and to assess the relationship of plasma calcitonin with ionized calcium, alkaline phosphatase (ALP), and urinary calcium excretion.

Animals

Thirty‐three client‐owned cats with azotemic CKD and ionized hypercalcemia from first opinion practice.

Methods

Cohort study. Calcitonin was measured with an immunoradiometric assay in heparinized plasma. Simple correlations were assessed with Kendall's rank correlation, and the within‐subject correlations of calcitonin with ionized calcium and other clinicopathological variables were calculated with a bivariate linear mixed effects model.

Results

Calcitonin concentrations above the lower limit of detection (>1.2 pg/mL; range, 1.7–87.2 pg/mL) were observed in 11 of 33 hypercalcemic cats (responders). Blood ionized calcium concentration did not differ significantly between responders (median, 1.59 [1.46, 1.66] mmol/L) and nonresponders (median, 1.48 [1.43, 1.65] mmol/L; P = 0.22). No evidence was found for calcitonin and ionized calcium to correlate between cats (τ_b = 0.14; P = 0.31; n = 33), but significant positive correlation was evident within individual responders over time (within‐subject correlation coefficient [r_within], 0.83; 95% confidence interval [CI], 0.63–0.92). Calcitonin correlated negatively over time with plasma ALP (r_within, −0.55; 95% CI, −0.79 to −0.16).

Conclusions and Clinical Importance

Calcitonin does not appear to have an important role in calcium metabolism in cats with CKD.

United States and European Multicenter Prospective Study for the Analytical Performance and Clinical Validation of a Novel Sensitive Fully Automated Immunoassay for Calcitonin

BACKGROUND

The objective of this study is the validation and proof of clinical relevance of a novel electrochemiluminescence immunoassay (ECLIA) for the determination of serum calcitonin (CT) in patients with medullary thyroid carcinoma (MTC) and in different diseases of the thyroid and of calcium homeostasis.

METHODS

This was a multicenter prospective study on basal serum CT concentrations performed in 9 US and European referral institutions. In addition, stimulated CT concentrations were measured in 50 healthy volunteers after intravenous calcium administration (2.5 mg/kg bodyweight).

RESULTS

In total, 1929 patients and healthy controls were included. Limits of blank, detection, and quantification for the ECLIA were 0.3, 0.5, and 1 ng/L, respectively. Highest intra- and interassay coefficients of variation were 7.4% (CT concentration, 0.8 ng/L) and 7.0% (1.1 ng/L), respectively. Medians (interval) of serum CT concentrations in 783 healthy controls were 0.8 ng/L (&lt;0.5–12.7) and 3 ng/L (&lt;0.5–18) for females and males, respectively (97.5th percentile, 6.8 and 11.6 ng/L, respectively). Diagnostic sensitivity and specificity were 100%/97.1% and 96.2%/96.4%, for female/males, respectively. Patients (male/female) with primary hyperparathyroidism, renal failure, and neuroendocrine tumors showed CT concentrations &gt;97.5th percentile in 33%/4.7%, 18.5%/10%, and 8.3%/12%, females/males, respectively. Peak serum CT concentrations were reached 2 min after calcium administration (161.7 and 111.8 ng/L in males and females, respectively; P &lt; 0.001).

CONCLUSIONS

Excellent analytical performance, low interindividual variability, and low impact of confounders for increased CT concentrations in non-MTC patients indicate that the investigated assay has appropriate clinical utility. Calcium-stimulated CT results suggest good test applicability owing to low interindividual variability.

Detection of Biosynthetic Precursors, Discovery of Glycosylated Forms, and Homeostasis of Calcitonin in Human Cancer Cells

The peptide hormone calcitonin is intimately connected with human cancer development and proliferation. Its biosynthesis is reasoned to proceed via glycine-, α-hydroxyglycine-, glycyllysine-, and glycyllysyllysine-extended precursors; however, as a result of the limitations of current analytical methods, until now, there has been no procedure capable of detecting these individual species in cell or tissue samples. Therefore, their presence and dynamics in cancer had not been established. Here, we report the first methodology for the separation, detection, and quantification of calcitonin and each of its precursors in human cancer cells. We also report the discovery and characterization of O-glycosylated calcitonin and its analogous biosynthetic precursors. Through direct and simultaneous analysis of the glycosylated and nonglycosylated species, we interrogate the hormone biosynthesis. This shows that the cellular calcitonin level is maintained to mitigate effects of biosynthetic enzyme inhibitors that substantially change the proportions of calcitonin-related species released into the culture medium.

Comparison of the prognostic values of selected inflammation based scores in patients with medullary thyroid carcinoma: A pilot study

BACKGROUND

The significance of inflammation based scores including the neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (dNLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), prognostic nutritional index (PNI), and plasma fibrinogen remains unclear in medullary thyroid carcinoma (MTC). We aimed to compare the prognostic value of these scores.

METHODS

Seventy-eight patients newly diagnosed as MTC with operation in our institution from May 2009 to September 2016 were retrospectively evaluated. Receiver operating characteristic (ROC) curves and Kaplan-Meier analyses were calculated to compare the prognostic value of these scores.

RESULTS

Increased PLR was predictive of lymph node metastasis (AUC = 0.644, P = 0.022), capsule invasion (AUC = 0.666, P = 0.007), advanced tumor stages (AUC = 0.657, P = 0.011), and recurrence (AUC = 0.655, P = 0.049). Increased fibrinogen was predictive of lymph node metastasis (AUC = 0.669, P = 0.006) and capsule invasion (AUC = 0.631, P = 0.038). Reduced PNI was predictive of recurrence (AUC = 0.655, P = 0.049). Kaplan-Meier analyses and Cox regression analysis revealed that PLR was a significant predictor for recurrence.

CONCLUSIONS

PLR, fibrinogen, and PNI are all predictive. Specially, PLR is superior to other inflammation based scores in terms of prognostic ability.

Serum calcitonin negative medullary thyroid carcinoma: a systematic review of the literature

Generally, calcitonin (CT) values below the upper reference limit rule-out medullary thyroid carcinoma (MTC) with very high accuracy. However, sparse cases of serum-calcitonin-negative MTC (CT-NEG-MTC) have been reported. Here we reviewed CT-NEG-MTC reported in literature, discussed the potential causes and proposed a practical laboratory and clinical approach. A comprehensive literature search was conducted by using the terms "medullary thyroid carcinoma" AND "non-secreting calcitonin" OR "undetectable calcitonin". The search was updated until December 2014. Original articles that described CT-NEG-MTC were eligible for inclusion. Only MTC cases with preoperative CT below the upper reference limit were included in the present review. Eleven papers with 18 CT-NEG-MTC cases (age 50 years, size 26 mm) were retrieved. Four patients with poorly differentiated MTC died within 3 years. Different CT assays were employed and different reference values were adopted. Preoperative serum CT values were below the institution cut-off levels in all cases, and undetectable in four patients. In some papers negative CT results were confirmed by additional tests. Further laboratory investigations were performed in some of the included studies. In patients with well founded suspicious of MTC and within the reference limits/undetectable CT other laboratory investigations [carcinoembryonic antigen (CEA), procalcitonin, CT stimulation, CT in washout of nodule's aspiration] have to be performed. Surgical approach to CT-NEG-MTC does not differ from those secreting CT. Postoperative follow-up of these rare cases should include periodical imaging and measurement of all potential markers. Patients with poorly differentiated MTC are at higher risk of disease-related death, and require more aggressive follow-up strategy.

Epidemiology and Clinical Presentation of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating from the thyroid C cells producing mainly calcitonin (CTN) used as tumor marker. MTC occurs either sporadic (75%) or in a hereditary form (multiple endocrine neoplasia type 2, MEN2), due to germline mutations in the RET proto-oncogene. The discovery of an MTC in a patient has several diagnostic implications involving a specific strategy: preoperative evaluation of the tumor marker CTN and the extent of the disease, classification of MTC as sporadic or hereditary by DNA testing, and screening for associated endocrinopathies in hereditary MTC. Elevated CTN is a highly sensitive and specific tumor marker for diagnosis and follow-up of MTC. CTN is directly related to the tumor mass. In patients with nodular thyroid disease, diagnosis of MTC could be made by CTN determination as an indicator of tumor burden in conjunction with fine-needle aspiration. Patients with confirmed sporadic or hereditary MTC should have a total thyroidectomy and depending on the preoperative CTN value and the extent of disease additional dissection of the lymph nodes in the central and lateral neck compartment. In MEN 2 patients diagnosed by screening, the time of prophylactic thyroidectomy depends on RET mutation and CTN level.

[Medullary thyroid carcinoma]

Medullary thyroid carcinoma (MTC) is a very rare malignancy, which arises from parafollicular C cells and accounts for 3-5% of all thyroid cancers. MTC represents a neuroendocrine tumor with a biology that differs considerably from differentiated thyroid cancer. Presence of a RET proto-oncogene germline mutation indicates hereditary C cell disease in the context of multiple endocrine neoplasia type 2 and hence a special treatment algorithm is required. Cure of MTC is only possible through surgery. Calcitonin screening is advocated for early MTC diagnosis and preoperative MTC management stratification. In case of surgically incurable persistent MTC, estimation of calcitonin and CEA doubling time is crucial to assess tumor biology and is complemented by multimodal imaging to assess tumor burden. Treatment decisions in incurable MTC must be carefully balanced with treatment-related morbidity, since MTC may take an indolent course over years.

Procalcitonin for detecting medullary thyroid carcinoma: a systematic review

The aim of the present study was to perform a systematic review of published studies to provide a robust estimation of the use of procalcitonin (ProCT) as a diagnostic marker of medullary thyroid carcinoma (MTC), with particular focus on its specificity and negative predictive value in excluding MTC. A comprehensive computer literature search was conducted to find relevant published articles on the topic. We used a search algorithm based on a combination of the terms 'medullary,' 'thyroid,' and 'ProCT.' The search was updated until February 2015. To expand our search, references of the retrieved articles were also screened. A total of 39 articles were retrieved, of which nine original papers published from 2003 to 2014 were selected for the review. Some of these studies used ProCT in the preoperative diagnosis of MTC, whereas others measured ProCT during the follow-up of patients who had been previously treated for MTC. Other laboratory measurements were performed in some of the included studies. The results of the majority of the studies indicate that ProCT measurement appears to be a very promising and reliable serum marker for the diagnosis of MTC, and it is not inferior to calcitonin (CT). The sample handling is less laborious, and in the few CT-negative cases reviewed, the assay had even greater sensitivity. It would be worthwhile to establish cutoff levels using larger patient series, because we speculate that this assay could potentially replace CT measurement in the future.

Surgical Treatment of Medullary Thyroid Cancer

Medullary thyroid cancer (MTC) can vary in tumor biology and progression. The most important indicator of distant metastases, determining clinical outcome, is lymph node metastasis to the neck and mediastinum. Surgical cure is within reach in node-negative tumors or node-positive tumors with fewer than 10 lymph node metastases. From a surgical point of view, compartment-oriented lymph node dissection, clearing gross, and occult metastases are important for locoregional tumor control. The discovery of missense germline mutations in the RET proto-oncogene and the close genotype-phenotype correlation in hereditary MTC promoted the worldwide breakthrough of prophylactic thyroidectomy. The best approach to hereditary MTC affords the DNA-based/biochemical concept, which is geared at limiting prophylactic surgery to total thyroidectomy at minimal surgical morbidity before the tumor can spread beyond the thyroid capsule. To improve outcome, routine calcitonin screening in nodular thyroid disease and DNA-based screening of the offspring in RET families are effective interventions.

Calcitonin as Biomarker for the Medullary Thyroid Carcinoma

Calcitonin (CTN) is a polypeptide hormone consisting of 32 amino acids with a disulfide bridge between position 1 and 7 that is mainly produced by the C-cells of thyroid gland. The measurement of CTN concentrations in blood reflects C-cell activity and is performed in general by immunoassay methods. However, there are analytical, physiological, pharmacological, and pathological factors that can influence results of serum CTN values. Due to the influence of these factors, there is a high variability in assay-dependent cutoffs used to discriminate between MTC, C-cell hyperplasia (CCH), and the absence of the pathological impairment of C-cells. There is a lot of evidence that the measurement of serum CTN concentrations in patients with thyroid nodules can lead to an earlier diagnosis of MTC or CCH than the exclusive use of imaging procedures and/or fine-needle aspiration cytology. Basal CTN concentrations higher than 60-100 pg/mL are highly indicative for the diagnosis MTC. In the range between cutoff and 60 pg/mL CTN, both MTC and HCC may be a relevant diagnosis. PCT and CTN appear to have a comparable diagnostic capability to diagnose MTCs. However, "positive" PCT values of more than 50 pg/mL may be reached also in subclinical infections and will lead, therefore, to an overdiagnosis of the tumor. Pentagastrin- or calcium-stimulated serum CTN concentrations higher than cutoff values might improve diagnostics of MTC, but the non-availability of the first and the lacking of relevant cutoff values for the second tool favors the use of only basal values currently.

Utility of serum procalcitonin for screening and risk stratification of medullary thyroid cancer

CONTEXT

The clinical utility of procalcitonin has not been demonstrated across the whole spectrum of medullary thyroid cancer (MTC).

OBJECTIVE

This serum biomarker validation study aimed at defining the diagnostic accuracy of procalcitonin for screening and risk stratification of MTC and delineating biochemical thresholds predictive of lymph node involvement in the neck and mediastinum.

DESIGN AND SETTING

This was a retrospective analysis at a tertiary referral center.

PATIENTS

Included in this study were 457 consecutive patients with previously untreated MTC, 112 of whom had procalcitonin and calcitonin serum levels determined before the initial operation.

INTERVENTION

The intervention was compartment-oriented surgery.

MAIN OUTCOME MEASURES

Main outcome measures included primary tumor diameter, extrathyroidal extension, lymph node metastases, distant metastases, and biochemical cure.

RESULTS

Receiver operating characteristics analyses revealed similar diagnostic accuracy for procalcitonin vs the current calcitonin standard, yielding comparable areas under the curve for primary tumors at thresholds of 10 (0.94 vs 0.93) and 40 (0.92 vs 0.84) mm; extrathyroidal extension (0.84 vs 0.83), lymph node metastasis (0.88 vs 0.86), and distant metastasis (0.93 vs 0.91). Lymph node metastases were present in the ipsilateral lateral neck with procalcitonin levels ≤1.0 ng/mL and the ipsilateral central neck with procalcitonin levels ≤0.25 ng/mL. Above a threshold of 1.0 ng/mL, lymph node metastases emerged in the contralateral central and lateral neck and above 5.0 ng/mL also in the upper mediastinum. When procalcitonin levels exceeded 1, 5, 10, and 50 ng/mL, biochemical cure rates declined to no more than 71%, 36%, 23%, and 10%, respectively.

CONCLUSION

Serum procalcitonin, having comparable diagnostic accuracy, has great potential to replace serum calcitonin as a new standard of care in the management of MTC because it does not need to be kept cool on ice or frozen and is easier to manage at the community level.

Development and application of a novel sensitive immunometric assay for calcitonin in a large cohort of patients with medullary and differentiated thyroid cancer, thyroid nodules, and autoimmune thyroid diseases

BACKGROUND

Serum calcitonin (sCT) is a useful biomarker for medullary thyroid cancer (MTC). Consensus has not been reached concerning sCT measurements in the evaluation of nodular thyroid disease (NTD).

OBJECTIVE AND METHODS

We developed a new immunofluorometric assay for sCT and have validated it in samples from 794 patients [203 with MTC, 205 with autoimmune thyroid disease (ATD), 248 with NTD, 80 with differentiated thyroid cancer (DTC) 'free of disease', 58 with chronic renal failure (CRF)] and 178 normal individuals, including samples after pentagastrin tests and samples from the washout of 92 FNA procedures in patients with NTD or MTC. We also compared some samples from patients with low or high calcitonin levels using both this assay and the Nichols Institute Diagnostics (NID) assay.

RESULTS

The assay's analytical sensitivity was 1.0 pg/ml. Considering MTC patients prior to surgery, the cut-off values for the 95% reference range were 11.1 pg/ml for males and 5.5 pg/ml for females and employing the ROC curve were 18.4 pg/ml for males and 7.8 pg/ml for females. sCT in patients with MTC was strongly correlated with disease status. Patients with NTD and ATD did not present false-positive results. sCT measurements were significantly correlated with age (excluding MTC and CRF). The NID test had a strong correlation with our assay. A hook effect was observed only with concentrations >200,000 pg/ml.

CONCLUSIONS

We developed a novel sCT assay and validated it in healthy subjects, as well as in a large cohort of patients with MTC, NTD, ATD, DTC, and CRF.

Comparison of serum calcitonin and procalcitonin in detecting medullary thyroid carcinoma among patients with thyroid nodules

BACKGROUND

To prospectively evaluate the role of procalcitonin (PCT) in detecting or excluding medullary thyroid carcinoma (MTC) among patients with thyroid nodules and increased calcitonin (CT) levels.

METHODS

Fourteen of 1236 patients referred for thyroid nodules had increased serum CT >10 pg/mL. A stimulation test with pentagastrin was done and both CT and PCT were measured after stimulation. All patients underwent thyroid ultrasound, fine-needle cytology and, if indicated, surgery with histological and immunohistochemical examination of the surgical specimens.

RESULTS

After follow-up, two MTCs were found. These two patients had basal CT >100 pg/mL and detectable (>0.1 ng/mL) PCT, with 100% sensitivity. Pentagastrin stimulated CT achieved values above 100 pg/mL in two MTCs and in other two cases with no MTC outcome (50% PPV and 83% NPV). On the contrary, all patients with no MTC had both basal and stimulated undetectable PCT (100% PPV and 100% NPV).

CONCLUSIONS

The addition of basal PCT measurement in patients with thyroid nodule(s) and increased CT may significantly improve accuracy of CT measurement without needing a PG stimulation test.

Influence of chronic autoimmune thyroiditis and papillary thyroid cancer on serum calcitonin levels

BACKGROUND

Serum calcitonin (sCt) is measured in many patients with nodular thyroid disease, and the possibility of a false-positive result is a matter of concern, particularly in the case of mild hypercalcitoninemia. Among the conditions reported to cause sCt elevation, Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma (PTC) are relevant. In view of the high frequency of these conditions in patients with nodular disease and the controversy regarding the extent to which they contribute to hypercalcitoninemia, the objective of this study was to determine the influence of the presence of HT and PTC on sCt levels.

METHODS

Three groups of patients >12 years of age were studied. The first group (group A, n=492) consisted of patients with nodular disease evaluated before thyroidectomy and without medullary thyroid carcinoma (MTC) upon histology. The second group (group B, n=583) consisted of subjects without nodules on ultrasound. The third group (group C, n=62) consisted of patients with PTC and distant metastases after total thyroidectomy. The levels of sCt and frequency of elevated sCt were compared in patients with versus without HT (groups A and B) and those with PTC>1 cm versus without PTC (group A).

RESULTS

No difference in sCt levels or in the frequency of elevated sCt was observed between patients with and without HT, irrespective of sex. Moreover, the presence of PTC>1 cm did not influence sCt levels or the frequency of hypercalcitoninemia. In fact, none of the 1075 patients in groups A and B had sCt>40 pg/mL, regardless of the presence of HT and PTC. Serum calcitonin was undetectable in any patient of group C.

CONCLUSIONS

The finding of hypercalcitoninemia in patients with nodular disease should be interpreted as a suspicion of MTC, even in the presence of associated HT or cytology suggestive of PTC.

German Association of Endocrine Surgeons practice guideline for the surgical management of malignant thyroid tumors

INTRODUCTION

Over the past years, the incidence of thyroid cancer has surged not only in Germany but also in other countries of the Western hemisphere. This surge was first and foremost due to an increase of prognostically favorable ("low risk") papillary thyroid microcarcinomas, for which limited surgical procedures are often sufficient without loss of oncological benefit. These developments called for an update of the previous practice guideline to detail the surgical treatment options that are available for the various disease entities and tumor stages.

METHODS

The present German Association of Endocrine Surgeons practice guideline was developed on the basis of clinical evidence considering current national and international treatment recommendations through a formal expert consensus process in collaboration with the German Societies of General and Visceral Surgery, Endocrinology, Nuclear Medicine, Pathology, Radiooncology, Oncological Hematology, and a German thyroid cancer patient support organization.

RESULTS

The practice guideline for the surgical management of malignant thyroid tumors includes recommendations regarding preoperative workup; classification of locoregional nodes and terminology of surgical procedures; frequency, clinical, and histopathological features of occult and clinically apparent papillary, follicular, poorly differentiated, undifferentiated, and sporadic and hereditary medullary thyroid cancers, thyroid lymphoma and thyroid metastases from primaries outside the thyroid gland; extent of thyroidectomy; extent of lymph node dissection; aerodigestive tract resection; postoperative follow-up and surgery for recurrence and distant metastases.

CONCLUSION

These evidence-based recommendations for surgical therapy reflect various "treatment corridors" that are best discussed within multidisciplinary teams and the patient considering tumor type, stage, progression, and inherent surgical risk.

Euthyroid goiter with and without nodules--diagnosis and treatment

BACKGROUND

Thyroid enlargement and thyroid nodules are common in the general population. This review concerns their proper diagnostic assessment and treatment.

METHODS

We selectively reviewed the literature from 1990 to 2012 and evaluated original articles and reviews retrieved from the PubMed database, as well as the recommendations of the following specialty societies: the German Societies of Endocrinology and Nuclear Medicine (Deutsche Gesellschaft für Endokrinologie, Deutsche Gesellschaft für Nuklearmedizin), the German Working Group for Endocrine Surgery (Chirurgische Arbeitsgemeinschaft Endokrinologie, CAEK), the European Thyroid Association, and the American Thyroid Association.

RESULTS

There have been very few randomized trials concerning the diagnosis and treatment of goiter. Nodular goiter can be managed by watchful waiting, drug treatment (initially with levothyroxine and iodide), radioactive iodine therapy, or surgery.

CONCLUSION

Many patients with nodules need no treatment at all. Treatment is indicated, however, if the patient is symptomatic and/or has an autonomously functioning ("hot") nodule, or if cancer is suspected. Potentially cancerous nodules must be operated on. If euthyroid nodular goiter is to be treated with the main goal of size reduction, either surgery or radioactive iodine therapy can be used. Drug treatment is an option for small nodules or goiters, but iatrogenic hyperthyroidism must be avoided at all costs. The type of follow-up that is required depends on the chosen treatment.

Advances in the follow-up of differentiated or medullary thyroid cancer

The long-term survival of patients with thyroid cancer and the possibility of tumour recurrence up to 30-40 years after the achievement of a disease-free status illustrate the importance of lifelong follow-up in these individuals. This Review discusses the most innovative aspects of follow-up protocols for patients with differentiated thyroid cancer, that is, of papillary or follicular hystotype, and those with medullary thyroid cancer. Particular focus is placed on the relevance of new ultrasensitive assays for thyroglobulin measurement and the option of using recombinant human TSH to stimulate thyroglobulin secretion. Methods to compensate for the loss of diagnostic significance of serum thyroglobulin levels in patients with differentiated thyroid cancer and circulating anti-thyroglobulin antibodies are highlighted, as well as the role of the postoperative calcitonin stimulation test and the clinical relevance of determining the doubling time of calcitonin and carcinoembryonic antigen in patients with medullary thyroid cancer. Moreover, this Review gives some insights into the role of molecular thyroid cancer testing, both for prognostic and for therapeutic purposes. Finally, a general overview of traditional imaging procedures, such as neck ultrasonography, CT, MRI and bone scintigraphy, is provided alongside a comparison with new nuclear imaging tests such as PET.