scholarly journals Measurement of Serum Free Thyroxine Index May Provide Additional Case Detection Compared to Free Thyroxine in the Diagnosis of Central Hypothyroidism

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Kevin M. Pantalone ◽  
Betul Hatipoglu ◽  
Manjula K. Gupta ◽  
Laurence Kennedy ◽  
Amir H. Hamrahian
Keyword(s):  
Elevated Serum ◽  
Free Thyroxine ◽  
Pituitary Hormone ◽  
Normal Range ◽  
Free T4 ◽  
Central Hypothyroidism ◽  
Serum Free ◽  
Free Thyroxine Index ◽  
Serum Tsh ◽  
Serum Free Thyroxine

The diagnosis of central hypothyroidism is often suspected in patients with hypothalamic/pituitary pathology, in the setting of low, normal, or even slightly elevated serum TSH and low free thyroxine (FT4). We present four cases of central hypothyroidism (three had known pituitary pathology) in whom central hypothyroidism was diagnosed after the serum free thyroxine index (FTI) was found to be low. All had normal range serum TSH and free thyroxine levels. This report illustrates that the assessment of the serum FTI may be helpful in making the diagnosis of central hypothyroidism in the appropriate clinical setting and when free T4 is in the low-normal range, particularly in patients with multiple anterior pituitary hormone deficiencies and/or with symptoms suggestive of hypothyroidism.

Serum free thyroxine in patients with T3-toxicosis

1985 ◽  
Vol 110 (3) ◽  
pp. 354-359 ◽  
Author(s):  
Enio Martino ◽  
Alessandro Pacchiarotti ◽  
Fabrizio Aghini-Lombardi ◽  
Lucia Grasso ◽  
Giovanni Bambini ◽  
...  
Keyword(s):  
Clinical Evidence ◽  
Elevated Serum ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Total Serum ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Serum Thyroxine ◽  
Free Thyroxine Index ◽  
Serum Free Thyroxine

Abstract. The serum free thyroxine concentration was measured by direct radioimmunoassay in 38 untreated T3-thyrotoxic patients with elevated serum total and free triiodothyronine, normal serum thyroxine and free thyroxine index, no TSH response to TRH, and with clinical evidence of hyperthyroidism. An elevation of circulating free thyroxine values was observed in 58% of the patients, whereas total serum thyroxine concentration was within the normal range. It is suggested, therefore, that T3-thyrotoxicosis should be reserved for patients with elevated serum total T3 and free T3 concentrations and normal serum total T4 and free T4 concentrations. Serum thyroxine-binding globulin concentrations were significantly lower (P < 0.025) in patients with an elevated serum free thyroxine (18.7 ± 3.6 μg/ml: mean ± sd) as compared with those in patients with a normal free thyroxine concentration (23.4 ± 2.6 μg/ml). In addition, no daily fluctuations in total and free thyroxine concentration were observed in 6 patients over a 4–8 day period.

Circadian thyrotropin variations are preserved in normal pregnant women

1995 ◽  
Vol 133 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Elio Roti ◽  
Luigi Bartalena ◽  
Roberta Minelli ◽  
Mario Salvi ◽  
Eliana Gardini ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Pregnant Women ◽  
Free Thyroxine ◽  
Third Trimester ◽  
Circadian Variations ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Trimester Pregnancy ◽  
Serum Tsh ◽  
Serum Free Thyroxine

Roti E, Bartalena L, Minelli R, Salvi M, Gardini E, Pistolesi A, Martino E, Braverman LE. Circadian thyrotropin variations are preserved in normal pregnant women. Eur J Endocrinol 1995;133:71–4. ISSN 0804–4643 Serum thyrotropin (TSH) concentration circadian rhythm is abolished in many endocrine and nonendocrine diseases. In the present study we have measured serum TSH concentration over 24 h every 2 h in second and third trimester pregnant women. During the 24-h period, serum free thyroxine and free triiodothyronine concentrations did not change significantly. In contrast, serum TSH concentrations demonstrated significant circadian variations both in the second and third trimester pregnant women (p<0.02 and p <0.005, respectively). In summary, second and third trimester pregnancy is associated with a normal circadian TSH rhythm. Elio Roti, Centro per lo Studio, Prevenzione, Diagnosi e Cura delle Tireopatie, University of Parma, via Gramsci 14, 1-43100 Parma, Italy

Artifactually Elevated Serum-Free Thyroxine Levels Measured by Equilibrium Dialysis in a Pregnant Woman with Familial Dysalbuminemic Hyperthyroxinemia

Thyroid ◽  
2004 ◽  
Vol 14 (2) ◽  
pp. 155-160 ◽  
Author(s):  
Saeko Hoshikawa ◽  
Kouki Mori ◽  
Nobuko Kaise ◽  
Yoshinori Nakagawa ◽  
Sadayoshi Ito ◽  
...  
Keyword(s):  
Pregnant Woman ◽  
Equilibrium Dialysis ◽  
Elevated Serum ◽  
Free Thyroxine ◽  
Serum Free ◽  
Serum Free Thyroxine

scholarly journals L-T4 Therapy in the Presence of Pharmacological Interferents

2020 ◽  
Vol 11 ◽  
Author(s):  
Salvatore Benvenga
Keyword(s):  
Thyroid Function ◽  
Cardiovascular Complications ◽  
Primary Hypothyroidism ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Central Hypothyroidism ◽  
Serum Free ◽  
Function Tests ◽  
Frequent Monitoring ◽  
Serum Free Thyroxine

Pharmacological interference on L-thyroxine (L-T4) therapy can be exerted at several levels, namely from the hypothalamus/pituitary through the intestine, where the absorption of exogenous L-T4 takes place. A number of medications interfere with L-T4 therapy, some of them also being the cause of hypothyroidism. The clinician should be aware that some medications simply affect thyroid function tests with no need of modifying the dose of L-T4 that the patient was taking prior to their prescription. Usually, the topic of pharmacological interference on L-T4 therapy addresses the patient with primary hypothyroidism, in whom periodic measurement of serum thyrotropin (TSH) is the biochemical target. However, this minireview also addresses the patient with central hypothyroidism, in whom the biochemical target is serum free thyroxine (FT4). This minireview also addresses two additional topics. One is the costs associated with frequent monitoring of the biochemical target when L-T4 is taken simultaneously with the interfering drug. The second topic is the issue of metabolic/cardiovascular complications associated with undertreated hypothyroidism.

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