Twenty-four-hour thyrotropin (TSH) profiles in eight severely ill patients were compared with those of six healthy subjects. The profiles were assessed using the cosinor method to evaluate circadian variations and using the Pulsar algorithm to analyze episodic secretion. In the normal subjects, the typical periodicity of TSH secretion showed a mean level in the rhythm (mesor) of 2.03 mU/l. The amplitude (half the extent of rhythmic change in the cycle) was 0.58 mU/l; the acrophase (the delay from midnight (0 degrees) of the highest level in the rhythm) was -9.9 degrees. In contrast, severely ill patients showed only slight and anticipated elevations of serum TSH levels (mesor 0.93 mU/l, amplitude 0.22 mU/l, acrophase +82.4 degrees). Moreover, whereas the episodic TSH secretion in healthy individuals consisted of 5-8 pulses/24 h, mainly clustered around midnight, only one pulse of reduced amplitude was detected in two of the eight severely ill patients and no pulses in the other six. Since earlier studies have indicated that the loss of TSH pulsatility is associated with the relative insensitivity of the thyrotrophs to low thyroid hormone levels and our analytical procedures have demonstrated that 24 h pulsatile pattern of TSH closely overlapped with baseline TSH secretion, it seems reasonable to assume that low-thyroid-hormone state, deficient pulsatile TSH secretion and altered nyctohemeral TSH periodicity do not coincide by chance, but that there is a causal relationship between such abnormalities in severely ill patients.
The aims of this study were to evaluate plasma lipid, apoprotein and Lp(a) levels in patients with severe coronary atherosclerosis undergoing aorto-coronary bypass surgery (BP) and to relate these parameters to the involvement of one or more vessels. Seventy-seven male patients and 77 cardiovascular disease-free controls, matched for sex, age and body weight were studied. Higher triglyceride and apo B levels with lower HDL-cholesterol and apo A-I levels were found in BP patients in comparison with the controls. Lp(a) levels were slightly, but not significantly, increased. Moreover BP patients presented a significantly higher prevalence of HDL-cholesterol levels below 35 mg dl-1 (49.3% vs 22.1%) and Lp(a) levels above 70 mg dl-1 (10.4% vs 1.3%) than the controls. When patients were divided according to the number of coronary vessels involved (one, two or three), no significant difference was found, with a trend to increase in Lp(a) mean levels and in prevalence of Lp(a) levels above 30 and 70 mg dl-1 in more severely diseased patients. These results suggest that patients with severe coronary artery disease undergoing aorto-coronary bypass surgery show low HDL-cholesterol levels with high triglyceride levels. Moreover Lp(a) levels above 70 mg dl-1 are highly associated with severe coronary vessel stenosis.
rhythm of serum thyrotropin in critically ill patients. Acta Endocrinol 1992;127:18-22. ISSN 0001-5598 To evaluate the 24-h pattern of serum thyrotropin (TSH) in critically ill patients, we measured serum concentrations of TSH in blood samples collected every 2 h for 24 h from nine patients (six with malignancy, two with liver cirrhosis, one with chronic renal failure), who had subnormal levels of both triiodothyronine (T3) and thyroxine (T4), in the absence of history, symptoms or signs of thyroid disease. Analysis of the data, performed using a second-order inferential statistical methodology for rhythmometry (cosinor method), demonstrated that critically ill patients still had daily oscillations of serum TSH which significantly adapted to the function approximating the circadian rhythms (R2 = 74.3%). However, the mean level (mesor) in the rhythm of the patients was found to be significantly lower than that of healthy subjects (0.96 vs 2.18 mU/l); the amplitude of rhythmical daily variations also was lower in patients than in healthy subjects (0.23 vs 0.56 mU/l), even though the amplitude/mesor ratio was similar (23% vs 26%). Lastly, the highest level in the TSH rhythm of the patients was found to be in the late afternoon, in contrast to healthy subjects, who had a TSH surge after midnight. Although these alterations are consistent with the existence of a dysregulation at suprahypophyseal level in critically ill patients, it remains to be established whether the state of low T3 and T4 may be ascribed to anomalous circadian rhythm of TSH.Alterations in circulating levels of thyroid hormones occur in a large number of patients with severe nonthyroidal illness, the most common being a fall in serum triiodothyronine (T3) and, in the critical phase, also in serum thyroxine (T4) levels (1). Despite these changes, such patients are not considered to be in a state of primary hypothyroidism because they did not have elevated thyrotropin (TSH) levels, but, as earlier reports have repeatedly documented, within the normal range.However, in some patients undergoing bone marrow transplantation (2), and in other critically ill patients (3-5), an impaired secretion of TSH coupled with hypothyroxinemia, a finding suggestive of a secondary hypothyroidism of a functional type, has been described.On the other hand, quantitative changes in TSH secretion cannot be estimated merely on the basis of single measurements in the morning hours. Serum concentration of circulating TSH markedly fluctuates over 24 h in relation to the rhythmical secretion from the pituitary, a gradual increase beginning in the late afternoon and the peak-level being attained around midnight (6). Since thyroid hormone secretion seems to depend on stimulation subsequent to the nocturnal surge of TSH (7), thyroid hypofunction in critical illness could rely on the absence of the typical circadian secretion of pituitary TSH.A decreased or absent nocturnal surge of TSH, despite morning concentrations being in the normal reference range, has been demonstrated in s...
In a previous study on the function of the hypothalamus -pituitary -thyroid axis, about 10% of postmenopausal women with the climacteric syndrome were found to have borderline high values of T3 and T4 and signs of pituitary decreased sensitivity to the suppressive effect of increased thyroid hormones. The present report concerns 5 women in the first phase of their menopause who showed a mild hyperthyroidism under basal conditions and after suppression test with liothyronine. Each patient had borderline increased levels of serum total and free T4 and T3 and a marked TSH responsiveness to exogenous TRH.After liothyronine, the serum levels of T4, FT4, TSH and the responsiveness to TRH-test clearly decreased. These data suggest an inappropriate TSH secretion with a decreased pituitary sentitivity to thyroid hormones.These cases could represent a modification of the hypothalamus-pituitary-thyroid axis associated with that of the gonadal axis, secondary to the absence of rapid adaptation of neurotransmitters.In a previous work we reported functional altera¬ tions in the hvpothalamus-pituitarv-thvroid axis during the first phase of the menopause (Custro et al. 1982).In the present study we selected women with borderline high values of serum T3 and T4. Such values are found in 10% of women menopaused for 1 to 5 vears and presenting a climacteric svndrome. This frequency is certainly higher than Requests for reprints:
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