Total and free thyroid hormone concentrations in patients receiving maintenance replacement treatment with thyroxine.

Pearce, C J; Himsworth, R. L.

doi:10.1136/bmj.288.6418.693

Cited by 100 publications

(36 citation statements)

References 11 publications

(1 reference statement)

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“…Several studies regarding the use of L-T 4 therapy to treat hypothyroidism showed that when serum T 4 levels are maintained at the upper limit of the normal ranges, serum T 3 levels are within the normal ranges (4,5,6,7,8). However, there have been few studies that compared postoperative T 3 levels in patients on L-T 4 therapy with their own preoperative endogenous levels.…”

Section: Introductionmentioning

confidence: 99%

“…Serum levels of TSH, FT 4 , and FT 3 were measured by a chemiluminescent immunoassay (ARCHTECT i2000; Abbott Japan). TSH assay showed an intra-assay coefficient of variation (CV) of 1.1-5.0% and an interassay CV of 1.7-5.3%.…”

Section: Thyroid Function Testsmentioning

confidence: 99%

“…In normal subjects, T 4 is secreted by the thyroid (about 100%) and T 3 as the active form is produced by the thyroid gland (about 20%) or is derived from the conversion of T 4 to T 3 in extra-thyroidal peripheral tissues (80%) (1). T 4 therapy using synthetic levothyroxine (L-T 4 ) is the standard of care for patients who had undergone total thyroidectomy (2,3).…”

Section: Introductionmentioning

confidence: 99%

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TSH-suppressive doses of levothyroxine are required to achieve preoperative native serum triiodothyronine levels in patients who have undergone total thyroidectomy

Miyauchi

Morita

et al. 2012

European Journal of Endocrinology

110

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Objective: Thyroidal production of triiodothyronine (T 3 ) is absent in patients who have undergone total thyroidectomy. Therefore, relative T 3 deficiency may occur during postoperative levothyroxine (L-T 4 ) therapy. The objective of this study was to evaluate how the individual serum T 3 level changes between preoperative native thyroid function and postoperative L-T 4 therapy. Methods: We retrospectively studied 135 consecutive patients with papillary thyroid carcinoma, who underwent total thyroidectomy. Serum free T 4 (FT 4 ), free T 3 (FT 3 ), and TSH levels measured preoperatively were compared with those levels measured on postoperative L-T 4 therapy. Results: Serum TSH levels during postoperative L-T 4 therapy were significantly decreased compared with native TSH levels (P!0.001). Serum FT 4 levels were significantly increased (P!0.001). Serum FT 3 levels were significantly decreased (PZ0.029). We divided the patients into four groups according to postoperative serum TSH levels: strongly suppressed (less than one-tenth of the lower limit); moderately suppressed (between one-tenth of the lower limit and the lower limit); normal limit; and more than upper limit. Patients with strongly suppressed TSH levels had serum FT 3 levels significantly higher than the native levels (P!0.001). Patients with moderately suppressed TSH levels had serum FT 3 levels equivalent to the native levels (PZ0.51), and patients with normal TSH levels had significantly lower serum FT 3 levels (P!0.001). Conclusions: Serum FT 3 levels during postoperative L-T 4 therapy were equivalent to the preoperative levels in patients with moderately suppressed TSH levels. Our study indicated that a moderately TSH-suppressive dose of L-T 4 is required to achieve the preoperative native serum T 3 levels in postoperative L-T 4 therapy.

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Section: Introductionmentioning

confidence: 99%

Section: Thyroid Function Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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TSH-suppressive doses of levothyroxine are required to achieve preoperative native serum triiodothyronine levels in patients who have undergone total thyroidectomy

Miyauchi

Morita

et al. 2012

European Journal of Endocrinology

110

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“…Together with the integration in CMOS, the here developed biosensor principle has a high potential for applications in the 10 pM to 0.1 M range, e.g. for the observation of thyroid functionality [14]. …”

Section: Resultsmentioning

confidence: 99%

CMOS based capacitive biosensor with integrated tethered bilayer lipid membrane for real-time measurements

Kißler

Pierrat

Zimmermann

et al. 2012

Biomedical Engineering / Biomedizinische Technik

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Conventional methods to investigate ionophore concentration require complex laboratory equipment. One approach to reduce the size of devices for the biosensor application is the implementation of the sensor circuits on CMOS microchips. Thus a new approach for the detection of changes in the ionophore concentration in tethered Bilayer Lipid Membranes (tBLMs) implemented in CMOS has been developed. In case of ion transport across the membrane by ionophores the ion concentration in the spacer region of the membrane is increased. This causes a permittivity increase and therefore a change of the capacitance of the spacer region which can be measured. The advantages of the capacitive biosensor principle are label-free measurements with short measurement times in the millisecond range. The test of the sensor chip with a circuit that mimics the membrane shows very good agreement between simulation and measurement. In addition, a Valinomycin concentration of 100 nM has been detected. An estimation of the detection limit gives a value of about 10 pM. IntroductionDetecting and quantifying ionophore activity is of utmost importance for biosensor applications, e.g. in the field of drug screening or the point-of-care-testing . A drawback, which consists, however, is that the measurement result has to be extracted from a graph. Both described methods are based on the change of the membrane resistance. Vockeroth et al. showed for the AChR ion channel M2 [6] that the spacer capacitance also changes in case of ion transport across the membrane. Since the change of spacer capacitance is smaller than the change of the membrane resistance, the effect has not been further investigated for the applicability in biosensing, yet. For CMOS integration of a sensor circuit the change in the spacer capacitance is an interesting aspect. Since the resistances of the biomimetic membranes are in the high Mega-Ohm range, they cause high noise voltages. Changes in capacitances, however, can be determined with a high read out accuracy with switched capacitor circuits [7]. Tethered bilayer lipid membranesSuitable biomimetic membranes for the embedding of ionophores are tethered bilayer lipid membranes, which are attached to a solid support via a spacer group to improve the long term stability of the biosensor [8].Glass slides with ultra flat template stripped gold (fabrication described in [9]) have been exposed to a solution of di-phytanyl-glycerol-tetraethylene-glycol-lipoic-acid-esterlipid (DPTL) in Ethanol in a concentration of 0.2 mM. They have been left for 24 h to build the monolayer of the membrane via self-assembling. After rinsing in pure ethanol and drying in a stream of nitrogen, the slides have been assembled in a measurement cell having a volume of 1 ml and an electrode area of 0.07 mm 2 . A vesicle solution of a suspension of 1 mg/ml di-phytanoyl-glycerophosphocholine (DPhyPC) in water has been produced by extrusion (Mini Extruder Kit) as described in [9]. The extruder and the DPhyPC have been purchased from Avanti Polar Lipid...

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“…According to Woeber K.A., a higher ratio of T4 to T3 is due to the suppression of the residual T3 secretion by the thyroid gland and low conversion of T4 to T3 in the peripheral tissues on the exogenous L-T4 therapy. It has been demonstrated in earlier studies, that replacement therapy of hypothyroidism with L-T4 is accompanied by increased ratio of T4 to T3 in the blood [Pearce CJ, 1984, Rendell M., 1985, Stock JM, 1974, and this ratio grows up with increasing doses of L-T4.…”

Section: Levels Of Thyroid Hormones On the Replacement Monotherapy Wimentioning

confidence: 99%

Options of Replacement Therapy in Hypothyroidism

Fadeyev¹,

Мельниченко²,

Моргунова³

2012

Hypothyroidism - Influences and Treatments

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Total and free thyroid hormone concentrations in patients receiving maintenance replacement treatment with thyroxine.

Cited by 100 publications

References 11 publications

TSH-suppressive doses of levothyroxine are required to achieve preoperative native serum triiodothyronine levels in patients who have undergone total thyroidectomy

TSH-suppressive doses of levothyroxine are required to achieve preoperative native serum triiodothyronine levels in patients who have undergone total thyroidectomy

CMOS based capacitive biosensor with integrated tethered bilayer lipid membrane for real-time measurements

Options of Replacement Therapy in Hypothyroidism

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