Levothyroxine-induced serum free thyroxine response following radioactive iodine administration in patients thyroidectomized for differentiated thyroid cancer: A randomized controlled trial

PURPOSE

Patients undergoing thyroidectomy for differentiated thyroid cancer (DTC) may require 131-radioactive iodine (RAI) administration for remnant ablation or disease treatment. After ingestion, RAI resides within the gastrointestinal tract potentially leading to mucosal damage and abnormalities in the absorption of levothyroxine (LT4). The aim of this study was to evaluate whether serum FT4 peak, induced by a LT4 challenge, changes according to the LT4 formulation (solid or liquid) in both RAI and non-RAI-treated DTC patients.

METHODS

This was a monocentric controlled clinical trial, with a parallel two-groups (1:1) randomization of sequence of LT4 formulation. Patients received 200 mcg LT4 orally administered at 08:00 h, in both solid and liquid formulation, at one-week interval, at baseline and after 1, 3, and 6 months from RAI administration. At each time-point, circulating FT4 was evaluated both before LT4 assumption as well as after 1 and 3 h. FT4 increments were evaluated as area under the curve response (AUC). Analogous protocol with the same time-intervals was followed for non-RAI patients.

RESULTS

The trial included 29 consecutive DTC patients, nineteen of whom were submitted to RAI. In RAI subjects, we observed an overall significant reduction in serum FT4 increments with the most relevant decrease at the 1-month time-point, (FT4 AUC: 4.46 ± 0.72 (M ± SD) vs 4.07 ± 0.63 in baseline vs 1-month, P = 0.001) without any difference between the two LT4 formulations. No difference in serum FT4 AUC was found in non-RAI subjects.

CONCLUSION

LT4-induced serum FT4 responses are reduced following RAI administration in thyroidectomized DTC patients.

Assessment of Access hsTnI 99th percentiles upper reference limits following IFCC recommendations

BACKGROUND

The detection of an increase and/or decrease of cardiac troponin (cTnI) values, with at least one value above the 99th percentile of the upper reference limit (URL) have a central role in acute myocardial infarction (AMI) diagnosis. The employment of sex specific 99th percentile URLs and High-sensitivity (Hs) assays are recommended. We assessed sex specific 99th percentile URL for Access Hs-cTnI and AccuTnI3+ (Beckman Coulter) using European donor reference population following recent International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommendations.

METHODS

300 males and 300 females plasma samples were collected. Both chemiluminescent immunoenzymatic assays were performed on UniCel DxI 800 platform (Beckman Coulter).

RESULTS

For Access hsTnI, the observed sex-specific 99th percentile URLs were 5.5 (90% CI: 4.4-7.6) for females and 13.9 ng/L (90% CI: 7.4-17.4) for males. For AccuTnI+3 we could not establish them because the assay couldn't report detectable values of troponin for most of the analyzed samples.

CONCLUSION

The sex-specific 99th percentile URLs established for Access hsTnI assay were significantly lower than those declared by the manufacturer caused by the different choice of population selection, age groups and sample types: for those reasons, we maintain the 99th URLs provided by manufacturer.

Analytical Evaluation of Free Testosterone and Cortisol Immunoassays in Saliva as a Reliable Alternative to Serum in Sports Medicine

BACKGROUND

This study was aimed to investigate whether measurement of free testosterone and cortisol in saliva is a reliable alternative to their assessment in serum for monitoring physical fitness in professional athletes.

METHODS

We studied 25 members of the soccer team Parma F.C., playing in Italian major football league. Blood and saliva samples were collected at fasting, before a regular training session. Cortisol, total and free testosterone, as well as the ratio between free testosterone and cortisol, were assessed in paired serum and saliva samples, and their results were compared.

RESULTS

An excellent correlation was found between serum and saliva cortisol (r = 0.751; P < 0.001). A significant correlation was also observed between free testosterone in serum and saliva (r = 0.590; P = 0.002), whereas no significant correlation was found between total testosterone in serum and saliva (r = 0.181; P = 0.387). A significant correlation was found for the free testosterone to cortisol ratio in serum and saliva (r = 0.43; P = 0.031). All athletes (25/25; 100%) declared that they would feel more comfortable to have saliva rather than blood serially collected.

CONCLUSIONS

The results of this study suggest that measurement of free testosterone and cortisol in saliva may be seen as a reliable alternative to their assessment in serum.

Analytical assessment of the novel Maglumi squamous cell carcinoma antigen (SCCA) immunoluminometric assay

BACKGROUND

The demand for routine measurement of squamous cell carcinoma antigen (SCCA) is rapidly increasing in clinical laboratories, due to the central role that this biomarker plays in staging and monitoring patients with various forms of squamous cell carcinomas (SCCs).

METHODS

The present analytical evaluation of Maglumi SCCA was aimed to assess the imprecision, linearity and comparability against a widely used technique.

RESULTS

The intra- and inter-assay imprecision was comprised between 2.6-4.2% and between 5.0-7.3%, respectively. The linearity of the test was excellent in the range of SCC values comprised between 1.0 and 18.0 ng/mL (r=0.998; P<0.001). A highly significant correlation was observed between Maglumi SCCA and BRAHMS Kryptor SCC in the range of values comprised between 0.44 and 15.18 ng/mL (r=0.960; P<0.001). The mean bias was 0.79 ng/mL (95% CI, 0.61-0.97) and the diagnostic agreement at the respective diagnostic cut-offs was 95%.

CONCLUSIONS

The results of this study confirm that Maglumi SCCA may be regarded as a suitable alternative to Kryptor SCC for routine and fully-automated assessment of SCCA in clinical laboratories.

Circulating concentrations of free thyroxine after an oral intake of liquid LT4 taken either during fasting conditions or at breakfast

BACKGROUND AND AIM OF THE WORK

Liquid levothyroxine (LT4) given at breakfast normalizes TSH in hypothyroid patients. However, a few studies are available on circulating free thyroxine (FT4) concentrations after liquid vs solid LT4 preparations.

METHODS

During an "ad interim" analysis on serum FT4 after 200 mcg liquid LT4 consumption while fasting in thyroidectomized thyroid cancer patients, we found that seven subjects fortuitously took liquid LT4 at breakfast. As established in the original protocol, serum FT4 was measured both at baseline as well as at 3 and 4 hours after solid or liquid LT4 consumption. We compared serum profile of FT4 in these subjects with those obtained in other subjects participating in the same study who took liquid LT4 (n. 7 subjects) or solid LT4 (n. 7 subjects) while fasting. The percentage increase of circulating FT4 was calculated at the above reported peak-times over the baseline values.

RESULTS

Circulating FT4 increased of about 40% in each group of subjects at both the 3rd and the 4th hour with no difference between these two time points in either group. The maximum FT4 % increase, irrespective of the time point, was 44.62 ± 3.05 (Mean ± SE), 44.84 ± 5.43, and 43.83 ± 1.30 after fasting solid, fasting liquid, and breakfast liquid LT4 consumption, respectively, with no differences among the three groups.

CONCLUSIONS

Circulating FT4 obtained after 3 and 4 hours from the ingestion of 200 mcg liquid LT4 is not influenced by meal and is comparable with that observed after solid LT4 preparations ingested while fasting.

Analytical evaluation of Diazyme procalcitonin (PCT) latex-enhanced immunoturbidimetric assay on Beckman Coulter AU5800

BACKGROUND

This study was aimed to evaluate the analytical performance of the novel Diazyme procalcitonin (PCT) immunoturbidimetric assay on Beckman Coulter AU5800.

METHODS

Diazyme PCT is a latex-enhanced immunoturbidimetric assay, developed for use on laboratory instrumentations with capability of reading absorbance at 600 nm. This analytical evaluation included the assessment of limit of blank (LOB), limit of detection (LOD), functional sensitivity, imprecision, linearity, carryover, and method comparison between Diazyme PCT and Kryptor PCT on 129 routine serum inpatient samples.

RESULTS

The LOB, LOD, and functional sensitivity of Diazyme PCT were 0.16, 0.26, and 0.28 ng/mL, respectively. The intra- and inter-assay imprecision of Diazyme PCT was between 2.9% and 7.8%. The linearity was excellent in the range of PCT values between 0.16 and 56 ng/mL, and the carryover was negligible (0.02%). A highly significant agreement was found between Kryptor PCT and Diazyme PCT in a range of concentrations between 0.16 and 111 ng/mL (Diazyme PCT=1.10×Kryptor PCT-0.89; r=0.960; p<0.001). The mean bias was 0.48 ng/mL (95% CI, -0.58 to 1.54 ng/mL). The strength of agreement between Kryptor PCT and Diazyme PCT was between 85% and 96% at 0.50, 2.0, and 10 ng/mL cutoffs.

CONCLUSIONS

Diazyme PCT appears to be a reliable assay for diagnosis and management of critical care patients susceptible to severe bacterial infections.

Characterization of skeletal parameters in a cohort of North Italian rugby players

BACKGROUND

Vitamin D deficiency is common in the general population and may impair skeletal muscle function. Very few data are available regarding this condition in professional athletes.

AIM

To evaluate some skeletal parameters and in particular serum 25-hydroxyvitamin D status in professional rugby players during two different sunlight exposure times (October and early April) and to assess its impact on bone metabolism.

MATERIALS AND METHODS

Twenty-one male healthy professional rugby players living in northern Italy at latitude of 44°55'N (age 24.6 ± 4.3 years; height 182.0 ± 0.05 cm; mass 96.3 ± 14.6 kg; BMI 28.9 ± 3.7 kg/m(2)) participated in this observational study. During 2012/2013 Italian rugby season, 25-hydroxyvitamin D, PTH and other related biochemical parameters were monitored. Dietary calcium intake and body composition by DXA were also evaluated.

RESULTS

Significant changes were observed between October and April data for 25-hydroxyvitamin D concentration (22.8 ± 5.8 vs. 19.1 ± 5.3 ng/ml; p = 0.001) whereas serum PTH, calcium and phosphorus plasma levels did not change. They presented with an appropriate daily intake of calcium (1,304.8 ± 477.9 mg; max 1,939 mg; min 228 mg).

CONCLUSIONS

Professional rugby athletes practicing a sport characterized by intense outdoor training and with good calcium intake are at higher risk of hypovitaminosis D that worsens significantly during times of low cutaneous vitamin D production. Further studies are warranted to evaluate whether an appropriate supplementation with cholecalciferol in professional athletes is needed.

Interference by heterophilic antibodies in immunoassays: wrong increase of myoglobin values

Aim of this work is to illustrate how analytical interference in immunoassay may produce serious errors in clinical laboratory results. The sophisticated quality assurance schemes used in many laboratories do not identify erroneous results arising from aberrant samples. Recently attention has been focused on the incidence and implication of false-positive results arising from the presence of certain substances in a patient's serum that interfere with one or more steps in immunoassays. In this paper, we present the case of a 92 year-old woman whose plasma myoglobin concentrations falsely increased when measured using the Beckman Access assay. We demonstrated that heterophilic antibodies accounted for the falsely increased myoglobin values, and we suggest how to resolve such situations.

[Application of a preoperative evaluation model in patients undergoing elective abdominal surgery]

We used a preoperative evaluation model based on the clinical history in order to determine the clinical characteristics of the patients. We also estimated the prevalence of asymptomatic disease in ASA1 patients and described the frequency of diagnosis that motivated suspension of the surgery during the preoperative time. Another purpose was to establish the perioperative complications according to the risk index and to detect the medical reasons for suspension of surgery during hospitalization. A total of 777 patients having an indication of surgery were evaluated in this program. Only 507 completed the preoperative evaluation. Of these, 57.79%, had at least one known disease or were diagnosed by their clinical history. Preoperative tests were indicated according to age in ASA1 patients. Complementary studies were indicated in relationship to the history and physical examination in ASA2 and ASA3 patients. After the evaluation, 27 surgeries were suspended: 21 were considered high risk, 2 suffered unknown active infections, and 4 ASA1 patients had severe asymptomatic anemia. A total of 328 patients were admitted for surgery. In 5 of these patients the anesthesiologist stopped the procedure in the operating room. The causes were acute decompensations of known pathologies. There were no complications or deaths related to unknown diseases and no patients died from cardiopulmonary or metabolic complications. In ASA1 patients, there were no complications related to this evaluation. This study allowed us to determine the clinical status of the patients and in consequence high-risk surgeries were canceled. In admitted patients a few surgeries were canceled for clinical reasons. This program probably decreased patient morbimortality, unnecessary hospitalization and costs.