Elevated serum thyroglobulin as a manifestation of acute haemorrhage into the thyroid gland

Serum thyroglobulin levels after fine-needle aspiration of thyroid nodules

OBJECTIVE

To investigate whether a minor insult to the thyroid gland attributable to fine-needle aspiration (FNA) or external thyroid palpation can cause a release of serum thyroglobulin (Tg) into the circulation.

METHODS

We determined serum Tg levels before and at 60 minutes and 15 days after FNA in 25 patients with thyroid nodules. Results were compared with those obtained in 25 patients with thyroid nodules, in whom serum Tg concentrations were determined before and 60 minutes after palpation of the thyroid, and in 15 healthy subjects without thyroid disease, who had no thyroid palpation and no FNA, from whom 2 blood specimens were obtained 60 minutes apart. All participants had normal results of thyroid function tests and no detectable antithyroglobulin or thyroid peroxidase antibodies.

RESULTS

After FNA, 22 of 25 patients had significant elevation of serum Tg concentrations. The Tg levels returned to baseline values 15 days after FNA. In 4 of the 25 patients with thyroid nodules who had palpation of the thyroid, a significant increase in serum Tg levels was elicited. None of the 15 healthy subjects with normal thyroid glands (and with no FNA or thyroid palpation) had significant Tg elevations.

CONCLUSION

FNA causes a significant increase in serum Tg concentrations, which may persist for 15 days. Therefore, Tg assay should not be scheduled prematurely after FNA.

Huge intrathyroidal hematoma causing airway obstruction: a multidisciplinary challenge

Thyroid hemorrhage is a relatively frequent event that in most cases causes pain and discomfort only, while rarely can cause significant neck swelling. Even more rarely, however, extensive thyroid hemorrhage can result in a rapidly expanding hematoma with airway compromise. We report a case of a rapidly expanding thyroid hemorrhage that occurred secondary to oral anticoagulation therapy in an 80-year-old patient with a previously existing goiter. The patient presented with acute onset of neck pain, dysphagia, and respiratory distress caused by tracheal compression from the thyroid mass. Computed tomography demonstrated a 6 x 9 x 10 cm mass consistent with an intrathyroidal hematoma projecting into the anterior mediastinum and displacing the trachea to the left. Rapid reversal of the coagulopathy was achieved with fresh frozen plasma and vitamin K. Consequently, the patient was managed conservatively with close observation, antibiotics, and steroids because no progression of airway compromise was manifested. Although the diagnosis can be easily established in these patients, no management guidelines of this condition exist. The potential of rapid airway compromise and the risk for exacerbation of bleeding in the light of significant elevation in the international normalized ratio (INR), make any airway management decisions very difficult. The importance of managing the airway and the haemostatic problem with the help of a multidisciplinary team is discussed.

Degree of thyrotropin suppression in differentiated thyroid cancer without recurrence or metastases

Forty-eight patients with differentiated thyroid cancer (DTC), who had no evidence of tumor recurrence or metastases on studies such as radioiodine scanning, neck ultrasonography, and with thyrotropin (TSH) and thyroglobulin (Tg) levels less than 1 mU/L and 5 ng/mL, respectively, were included in the study. The mean age was 43 +/- 12 years (range 15-65) and all were receiving levothyroxine (LT4) treatment with a mean dose of 184 +/- 46 microg daily. Patients were divided into two groups; group A included patients that had baseline TSH levels of 0.4 mU/L or more, and group B patients had baseline TSH levels of less than 0.4 mU/L. LT4 doses for all patients were increased, and serum TSH and Tg measurements were reevaluated after 2 months of dose increments. The mean TSH of group A (patients with baseline TSH levels > or = 0.4 mU/L) decreased from 0.67 +/- 0.28 mU/L to 0.16 +/- 0.08 mU/L (p < 0.001), but mean serum Tg level showed no change after dose increments (2.92 +/- 1.36 ng/mL vs. 3.59 +/- 0.93 ng/mL at the second month; p > 0.05). Similar results were also observed in group B (patients with baseline TSH levels < 0.4 mU/L). Mean TSH level decreased from 0.26 +/- 0.07 mU/L to 0.1 +/- 0.05 mU/L (p = 0.006), but no decrease occurred in mean Tg level (3.0 +/- 1.16 ng/mL vs. 3.3 +/- 1.03 ng/mL; p > 0.05). The patients' data were reevaluated according to second-month TSH levels. Patients with a TSH level between 0.11 to 0.4 mU/L were set as "final TSH > 0.1 group," and patients with a TSH level equal or less than 0.1 mU/L were set as "final TSH < or = 0.1 group," and baseline and second-month Tg levels were assessed. The mean second month Tg levels did not differ in these two patient groups (3.7 +/- 0.74 ng/mL for final TSH > 0.1 group vs. 3.3 +/- 1.2 ng/mL for final TSH < or = 0.1 group; p > 0.05). No difference could be found between initial and second-month Tg levels in both groups (2.8 +/- 1.4 ng/mL vs. 3.7 +/- 0.74 ng/mL in final TSH > 0.1 group and 3.11 +/- 1.1 ng/mL vs. 3.3 +/- 1.2 in final TSH < or = 0.1 group; p > 0.05). In conclusion, these results indicate that serum Tg levels cannot be suppressed by maximal TSH suppression in tumor-free DTC patients. The suppression of TSH to less than 0.1 mU/L seems not to be necessary in most patients who have no evidence of active disease.

Analytical goals for quantities used to assess thyrometabolic status

Analytical goals for imprecision derived from data on intra-individual variation for total T4, free T4, total T3, free T3 and thyrotropin (TSH) are coefficients of variation (CV) less than or equal to 2.5, 4.7, 5.2, 3.9 and 8.1%, respectively. If total T4 is used to monitor replacement therapy with thyroxine, a more stringent goal of CV less than or equal to 1.4% is appropriate. For those analytes for which biological variation data are not available, analytical goals may be derived either from reference intervals or from the 'state of the art' as judged from the performance of a stated proportion of laboratories participating in an interlaboratory quality assessment scheme. Analytical goals for imprecision for reverse T3 and thyroxine-binding globulin derived from reference values are CV less than or equal to 10.7 and 7.2%, respectively. The goal for inaccuracy is that there should be none. Statements regarding the detection limit of an assay should be replaced with information about the range of concentrations over which specified goals for imprecision are met. If goals are not achieved at concentrations which are used for clinical decision making the 95% confidence limits of the extreme values of the 'working range' should be calculated using the relevant imprecision. Improved analytical performance will result in better between-laboratory comparability and eventually allow the use of universally applicable reference values.