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Diurnal variations of serum thyroid hormones was evaluated in hypothyroid
patients on replacement L-T4 therapy by Faria
et al. (Sào Paulo, Brazil). They examined serum TSH and
thyroid hormone levels in two groups. Group A was composed of 24 patients,
aged 53.7 ± 18.7 yr. (mean ± SD) with primary hypothyroidism
on L-T4 replacement (2.21 ± 0.58 µg/kg/daily)
and group B, used as control, of 10 euthyroid individuals, aged 50.3 ±
13.1 yr. In group A, blood samples were taken while the patient was fasting
(sample 0), an hour after the patient had taken L-T4
(sample 1) and at 16:00 h (sample 2). In group B only samples 0 and 2 were
taken. Serum TSH (3rd generation), total T4, T3
and free T4 were evaluated by chemoluminescent assay
(DPC-immulite). Kruskal-Wallis and MannWhitney statistical tests were used.
No differences were observed in group A when comparing TSH values of samples
0 (5.74±3.0 µU/mL) vs. 1 (4.96±12.3 µU/mL), 0
vs. 2 (7.56±16.7 µU/mL) and 1 vs. 2. Similar results were
observed in group B (sample 0 = 1.71±1.1 vs. sample 2 = 1.23±.42
µU/mL). No differences wee also noted in T4,
T3 and free T4 serum concentration.
There was a significant difference (p=0.001) of TSH and T4
concentrations of samples 0 between groups A (TSH = 6.74±3.0 µU/mL,
T4 = 8.4±3.0 µg/dL) and B (TSH = 1.71±1.13
µU/mL, T4 = 9.5±1.4 µg/dL), but
no difference was found between the values of samples 2 (TSH = 7.56±16.7
µU/mL; T4 = 8.8±2.7 µg/dL and TSH
= 1.23±0.42 µU/mL; T4 = 8.6±1.1
µg/dL). Besides in group A, 6 patients (25%) had elevated serum TSH
and 4 (17) had suppressed TSH values but no difference was found between
the L-T4 dosage (1.68±1.1 vs. 1.75±0.36
µg/kg/day) between these patients. The authors concluded that during
the daytime there is no major variability of the values of serum thyroid
hormones and TSH levels in hypothyroid patients on L-T4
therapy.
Thyroid function changes in acquired immunodeficiency syndrome (AIDS) and the prognostic role of T3 levels was evaluated by Sgarbi and co-workers (Marilia, Brazil). They have analyzed, prospectively, thyroid function of 53 HIV-infected individuals (M=31, F=22), whose ages ranged between 17 and 63 years. The HIV- infected individuals were divided into three groups according to the number of CD4+T cells (by cu. mm): G I - <200 (n="36," AIDS patients); G II 200 to 499 (n="12," HIV-infected) and G III>499 (n=5, HIV-infected). As controls, 15 healthy volunteers (G IV) and 15 patients from Intensive Care Unit (ICU - G V) were also studied. In all patients and controls were submitted to the determination of serum TSH, T3, T4, FT4 levels, TSH stimulation test with TRH and CD4+, CD8+ T-cell measurement. The TSH levels were higher in G I than in the controls (G IV and G V), but it was not different from the G II and G III. G I presented lower FT4 levels and higher T4 levels than G IV, but these parameters did not differ from those in G II, G III and G V. G I patients showed lower T3 levels (1.02 ng/mL) than G II (1.45 ng/mL), but higher than G V (0.47 ng/mL). On the other hand, 12 out of 36 G I patients with clinically active opportunistic infections, revealed low T3 serum levels (0.7 ng/mL), which were not different from those observed in G V. Analyses of thyroid function revealed 5 patients with hypothyroidism, all of them in G I. Serum T3 levels presented a positive correlation with the CD4+ T-cell (r=0.49) and a negative with mortality (p=0.0045). These findings demonstrated an important involvement of thyroid function in the final stage of AIDS disease, and indicated that the serum T3 level may be used as a prognostic parameter in these patients. |
