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Biomedical subjects

T Helenius

Publications and source records attributed to T Helenius.

27 records · Page 2Linked to original sources
PubMed1982

Serum levels of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D and parathyroid hormone in patients with femoral neck fracture in southern Finland.

Serum concentrations of 25-hydroxyvitamin D (25-OHD), 24,25-dihydroxyvitamin D [24,25(OH)2D] and immunoreactive parathyroid hormone (PTH) were determined in elderly patients with fracture of the femoral neck and in age-matched controls during summer, winter and early spring in southern Finland. The expected seasonal variation in 25-OHD values was observed in both patients and controls, though the patient group had significantly lower values during winter (P less than 0.02) and spring (P less than 0.01). The 24,25(OH)2D:25-OHD ratio remained constant in both patients and controls throughout the study. A significant negative correlation between PTH and 25-OHD values was found in the patient group. Thus, vitamin D deficiency may contribute to the high incidence of femoral neck fractures in elderly people, and the increased PTH activity, observed in many patients with these fractures, is secondary to vitamin D deficiency.

24,25-Dihydroxyvitamin D 3↗
PubMed1982

Effect of parenteral nutrition on the blood levels of insulin, glucagon, growth hormone, thyroid hormones and cortisol in catabolic patients.

The changes in plasma insulin (IRI) glucagon (IRG), IRI:IRG ration, growth hormone (HGH), cortisol and thyroid hormones during two different but isocaloric parenteral nutrition regimens were investigated in 11 malnourished patients and 21 postoperative patients. The nutrition program which used glucose as a non-nitrogen energy source favoured anabolism by a higher rise in plasma IRI and by a higher rise in the initially low plasma IRI:IRG ratio in both malnourished and postoperative patients more than the alimentation regimen with glucose and lipid. The glucose program augmented the IRI:IRG ratio to an average of 5.5 +/- 1.2 (SEM) in malnourished patients and to 8.4+/-2.7 in postoperative patients. The corresponding values for the glucose-lipid program were 3.9+/- 1.0 and 1.9 +/- 0.4. In malnourished patients the difference between the anabolic effect of these nutrition regimens was further increased by a fall in the plasma HGH level to 0.7 +/- 0.3 microgram/l during fat infusion. Over a period of four days both alimentation programs similarly increased in the initially low serum T3 and free T3 index to the normal reference interval and decreased serum rT3 to a subnormal level (0.18+/-0.7 nmol/l) in malnourished patients. In postoperative patients the only change in thyroid hormones which was dependent on the four-day parenteral nutrition was the decrease in the initially elevated serum rT3 to the normal reference interval by both alimentation programs (by 54% in the glucose and by 30% in the glucose-lipid program).

Adult↗
PubMed1980

Effect of anticonvulsant and antidepressant drugs on iodothyronines in serum.

Serum iodothyronine concentrations were measured in patients on long-term therapy with one or two anticonvulsant drugs. Diphenylhydantoin (DPH) and carbamazepine (CBZ) reduced the serum levels of thyroxine (T4) free T4 index, reverse triiodothyronine (rT3) and 3,3'-diiodothyronine (3,3'-T2), whereas the depressant effect on the serum levels of triiodothyronine (T3) and free T3 index was small but statistically significant. In patients administered DPH and phenobarbital (PB) or CBZ and primidone (PD) the serum iodothyronine levels were also depressed, except for normal T3 and free T3 index. Patients receiving only PB or PD had normal serum levels of total and free thyroid hormones, but decreased concentrations of rT3 and 3,3'-T2. Only supratherapeutic concentrations of DPH and CBZ added in vitro to control sera significantly reduced the number of T4 and T3-binding sites, as reflected in increased T4 and T3 uptake test results. This indicates that the DPH and CBZ-induced decrease in thyroid hormone concentrations in vivo is not due to a displacement of thyroid hormones from their binding sites on serum proteins. The antidepressant drugs amitriptyline and mianserin had no effect on the thyroid hormone levels in serum.

Adult↗
PubMed1979

Abnormal thyroid function tests in devere non-thyroidal illness: diagnostic and pathophysiologic aspects.

In vitro thyroid function tests were studied in twenty-three patients with serious non-thyroidal illness. All had reduced protein binding of serum thyroxine (T4) and serum triiodothyronine (T3) as reflected in increased T4 and T3 uptake tests. The mean T4-binding prealbumin (TBPA) capacity and concentration were about one third the normal levels, whereas the decrease in R4-binding globulin (TBG) was much smaller. Increased serum free fatty acids and reverse T3 were frequently observed, but in vitro displacement of thyroid hormones from their binding sites was achieved only with much high concentrations of these compounds. Other still unrecognized substances significantly inhibiting binding of thyroid hormones might, however, occur in sera of severely ill patients. Evidence in favour of this possibility was the disproportionately high serum T4 by TBG-binding assay relative to T4 by radioimmunoassay. In most of the patients the dual-stage free T4 was elevated, whereas the single-stage free T4 index (CT4I) was within the reference interval. However, neither of these indices reflected the moderately increased dialysable free T4 concentration very accurately. The free T3 index was depressed in most of the patients, whereas the dialysable free T3 concentration was not affected. For practical purposes the combination of normal serum T4 and CT4I in a severely ill patient indicates absence of an associated thyrometabolic disorders.

Adult↗
PubMed1978

Thyroid function tests in patients on long-term treatment with various anticonvulsant drugs.

Thyroid function tests were studied in patients undergoing long-term treatment with various anticonvulsant drugs. Previous reports that diphenylhydantoin induces a decrease in the serum concentrations of total and free thyroxine (T4) and triiodothyronine (T3) without a change in the TSH concentration were confirmed. Diphenylhydantoin had no effect on reverse T3. Carbamazepine was also found to decrease serum T4, the free T4 index and T3 but, with the exception of T3, the decrease was smaller than that induced by diphenylhydantoin. Dipropylacetic acid did not influence the serum thyroid hormone concentrations, and neither did primidone. This demonstrates that the interaction between anticonvulsant drugs of different chemical structure and thyroid hormone metabolism is diverse. None of the drugs tested altered serum TSH or the T3 uptake test for the estimation of unsaturated thyroid hormone binding-capacity in serum. These two tests are considered diagnostically more dependable than the measurement of thyroid hormones in serum when diphenylhydantoin and carbamazepine are administered.

Adolescent↗
PubMed1978

Acute effects of alcohol on anterior pituitary secretion of the tropic hormones.

The plasma or serum concentrations of GH, TSH, LH, PRL, testosterone, cortisol, T4, and T3, and the values of the T3 uptake test were monitored in 12 healthy male volunteers for a period of 20 h after administration of one large dose of ethanol (1.5 g/kg BW). The effects of TRH and LRH on the secretion of TSH, PRL, and LH were studied in these subjects once during the period of acute alcohol intoxication (4 h after the start of drinking) and once during the hangover period (14 h after the start of drinking). Each subject served as his own control by drinking water only during another experimental session. Alcohol had no significant effect on basal concentrations of GH, TSH, LH, T4, T3, or testosterone. The concentration of cortisol in plasma was elevated during the whole 20-h period after ingestion of alcohol, as compared with the control values. Alcohol also did not significantly alter the effects of TRH and LRH on plasma TSH and LH levels at 4 and 14 h. During the hangover period, the PRL response to TRH was totally blocked, but during alcohol intoxication, there was a slight increase in the PRL response to TRH. The lack of response of PRL to TRH during the hangover suggests that withdrawal symptoms are associated with increased dopaminergic activity in the hypothalamus.

Adolescent↗
PubMed1976

Effect of fatty acids on thyroid function tests in vitro and in vivo.

Addition of long-chain fatty acids to serum increased thyroxine (T4), measured by a competitive protein binding assay, and triiodothyronine (T3) uptake by Sephadex or resin (T3U tests). This is compatible with the assumption that fatty acids compete with thyroxine for binding sites on T4-binding proteins. When equimolar concentrations of various saturated and unsaturated fatty acids were added to serum it was observed that the effectiveness in raising tests based on protein binding of thyroid hormones incrreased serum T3 determined by radioimmunoassay (RIA). T4(RIA) was not significantly influenced by either saturated or unsaturated fatty acids. Serum T4(CPB) rose during storage at 22degreesC and 37degreesC but was stable at 4degreesC and --20degreesC for periods up to two weeks. The proportional increase in T4(CPB) and free fatty acids (FFA) indicated that this phenomenon was due, at least partly, to the interference from FFA formed during storage of the serum. There was also a small, significant increase in T3U, T3(RIA) and CT4I (a free thyroxine estimate) after storage of serum at room temperature or higher for one to two weeks. Serum T4(RIA) did not alter during two weeks of storage. In five subjects with raised serum FFA after eating a fat meal followed by a heparin injection an increase in T4(CPB), T3U, T3(RIA) and CT4I that was proportional to the increase in FFA was observed. This effect on the thyroid tests was small until the increase in FFA concentration exceeded 2 mmol/l. T4(RIA) did not respond to the increase in FFA. In ten patients with raised levels of FFA due to uncontrolled diabetes T4(CPB), T4(RIA) and T3(RIA) decreased while T3U increased. These unexpected alterations were probably related to the severe, chronic illness in these patients. Increased FFA in vivo seem to be of little importance for the interpretation of thyroid tests in clinical practice.

Adult↗
PubMed1975

Comparison of serum free thyroxine indices and "corrected" thyroxine tests.

A dual competitive protein-binding assay for serum thyroxine (T4) is described. The assay is called the "corrected" T4 index and can be performed simultaneously with the determination of total T4. This method correlated significantly with the free T4 index and the effective T4 ratio. The "corrected" T4 index was compared for precision and diagnostic accuracy with the effective T4 ratio and two different free T4 indices. Improved modifications of the thyroxine and triiodothyronine Sephadex uptake tests, used for calculation of the free T4 indices, are also reported. In spite of better precision, the "corrected" T4 index and effective T4 ratio gave twice as many incorect classifications of both hyper- and hypothyroidism as the free T4 indices. Previous reports on the effective T4 ratio and other basically similar tests might give an overly optimistic view of what can be expected in routine clinical practice. The free T4 index, which is a good estimate of the free T4 concentration, may still be the thyroid function test of choice when serum T4 and clinical impression are not in conformity.

Adult↗