Search PubMed⌕ Search

Biomedical subjects

G Caldwell

Publications and source records attributed to G Caldwell.

At least 37 records · Page 2Linked to original sources
PubMed1987

Relationship between pituitary and other target organ responsiveness in hypothyroid patients receiving thyroxine replacement.

This study was undertaken to compare the sensitivity of the thyrotrophs to that of other tissues to T4 treatment in hypothyroid patients. To do so, we measured serum total and free thyroid hormones and TSH, in addition to several serum markers of peripheral tissue response to thyroid status, in 21 hypothyroid patients treated with 50-micrograms increments of T4 to a maximum of 200 micrograms daily (group I) and in 104 clinically euthyroid patients receiving a long term constant replacement dose (group II). In group I patients, dose-dependent increases (P less than 0.05) in serum glutathione S-transferase, sex hormone-binding globulin, and angiotensin-converting enzyme occurred, whereas serum T4-binding globulin, creatine kinase, and creatinine levels decreased (P less than 0.05). In both patient groups, abnormally high levels of glutathione S-transferase, sex hormone-binding globulin, angiotensin-converting enzyme, alanine aminotransferase, and gamma-glutamyl transferase were found in some patients during treatment. One or more of these biochemical abnormalities suggestive of hyperthyroidism occurred in 15 (71%) group I patients and 27 (26%) group II patients. These were associated with an undetectable serum TSH (less than 0.1 microU/ml) and raised free T4 concentrations in 13, and raised free T3, T4, and T3 concentrations in only 8, 6, and 1 group I patients, respectively. In group II patients, they were more closely associated with an undetectable TSH (67%) or raised free T4 (85%) level than with raised concentrations of free T3 (33%), T4 (26%), or T3 (0%). The use of high sensitivity TSH assays will permit more accurate adjustment of T4 replacement and minimize abnormalities in peripheral tissue biochemistry indicative of overtreatment.

Adolescent↗
PubMed1987

Value and limitations of a highly sensitive immunoradiometric assay for thyrotropin in the study of thyrotroph function.

Using a highly sensitive and specific immunoradiometric assay for thyrotropin, we studied thyrotroph function in 232 new patients referred to a thyroid clinic and in 13 patients after treatment for hyperthyroidism. Significant thyrotroph responsiveness to thyroliberin (thyrotropin-releasing hormone, TRH) was found in all patients with values for basal thyrotropin greater than 0.1 milli-int unit/L. In no overtly hyperthyroid patient was any increment in thyrotropin recorded at 20 min after thyroliberin administration. In seven patients, four subclinically hyperthyroid and three who had received treatment, increments in thyrotropin from undetectable basal values were recorded, consistent with incomplete thyrotroph suppression. By use of assays with even higher sensitivity, one may be able to distinguish these patients from overtly hyperthyroid patients.

Adolescent↗
PubMed1987

Fasting hyperinsulinemic hypoglycemia after ritodrine therapy for premature labor.

A 26-year-old woman with a triplet pregnancy was treated prophylactically with ritodrine beginning at 15 weeks' gestation. At 32 weeks, she was admitted in preterm labor, and over the next 12 days received high-dose oral or intravenous ritodrine. Three female infants were delivered by cesarean section after spontaneous rupture of the membranes. Postoperatively, she developed profound hypoglycemia with inappropriately high insulin levels. Maternal hypoglycemia after ritodrine therapy in pregnancy has not been reported previously. We discuss possible mechanisms.

Adult↗
PubMed1986

An improved approach to thyroid function testing in patients with non-thyroidal illness.

We have compared the results of serum thyrotrophin (TSH) measurements using a sensitive immunoradiometric assay (IRMA) with those of conventional thyroid function tests in 299 hospital inpatients with a range of non-thyroidal illnesses. Levels of total thyroxine (T4), free T4, total tri-iodothyronine (T3) and free T3 in the hypothyroid range were recorded in 8%, 15%, 19% and 49% of patients, respectively, whereas TSH (IRMA) was abnormally low in 1%. Furthermore, basal TSH (IRMA) accurately predicted the result of the thyrotrophin-releasing hormone test in 72 of the 74 patients in whom this test was performed and, unlike thyroid hormone measurement, identified patients with subclinical thyroid disease. It would appear that a single basal TSH (IRMA) measurement is the most appropriate screening test for thyroid dysfunction in patients with concomitant acute or chronic illness.

Adolescent↗
PubMed1986

Two concurrent epidemics of enteroviral meningitis in an obstetric neonatal unit.

A small epidemic of viral infection occurred in a neonatal unit. It involved 11 infants, all of whom recovered. Echovirus 11 was the cause of illness in six infants, coxsackie B3 in four, and one infant had a biphasic illness, due first to echo 11, then to coxsackie B3. The epidemic coincided with a major outbreak of echovirus 11 and a smaller outbreak of coxsackie B3 in the community. Several staff became ill. Five infants were considered to have been infected by perinatal materno-infant spread, others by cross-infection. The epidemic ended when the nursery was closed.

Australia↗
PubMed1986

SimulTRAC simultaneous radioimmunoassay of thyrotropin and free thyroxin evaluated.

We assessed the analytical and diagnostic performance of a dual-isotope RIA for thyrotropin (TSH) and free thyroxin (FT4) in serum. The mean interassay CVs for these analytes were 7.9% and 5.0%, respectively. The mean minimum detection limit for TSH was 0.25 milli-int. unit/L, the mean analytical recovery 110%. There was good agreement with values for TSH and FT4 measured by alternative RIA procedures. Euthyroid patients were well distinguished from those with overt thyroid disease, although there was a small overlap in the case of TSH. Combining the two results better discriminated these categories and identified those patients with subclinical thyroid disease who had abnormal TSH concentrations but FT4 concentrations within reference limits. Euthyroid women taking estrogen-containing oral contraceptives had normal results for TSH and FT4, as did most pregnant women studied. During the third trimester of pregnancy, TSH concentrations of women with low FT4 concentrations were within reference limits. Similarly, euthyroidism was confirmed in patients with low FT4 due to nonthyroidal illness by the simultaneous finding of a normal TSH concentration.

Adult↗
PubMed1985

Simple mechanical methods for cardioversion: defence of the precordial thump and cough version.

A prospective study was made of the value of the precordial thump and of cough version in life threatening ventricular arrhythmias. Of about 5000 medical and surgical patients, 68 were treated for persistent ventricular tachycardia and 248 for ventricular fibrillation, 86 of whom had presented outside hospital. Mechanical intervention was successful in 26 incidents occurring in 23 patients. Electrocardiographic records were obtained in 14 instances. Ventricular fibrillation was terminated by a thump in five patients and ventricular tachycardia by either a thump or a cough in a total of 17 patients. Four additional instances were recorded of successful recovery from asystolic or unspecified circulatory arrest after a precordial thump. Fifteen patients survived to be discharged from hospital. The potential benefit of the precordial thump and cough versions greatly outweighs their risks; hence these manoeuvres should probably be reintroduced into schedules for first aid resuscitation.

Aged↗
PubMed1985

A new strategy for thyroid function testing.

In view of the increasing number of in-vitro tests of thyroid function, rationalization of the biochemical assessment of patients with suspected thyroid disease was attempted. In addition to clinical examination of 285 consecutive new referrals to a thyroid clinic, measurements were made of serum total and free triiodothyronine (T3) and thyroxine (T4) and of thyrotropin (TSH) by radioimmunoassay before and 20 min after thyrotropin-releasing hormone (TRH) and basal TSH by immunoradiometric assay (IRMA). Analysis of these results demonstrated that: (i) a detectable and normal TSH (IRMA) result indicates that the patient is euthyroid and obviates the need for measurement of thyroid hormones and (ii) a raised or undetectable TSH (IRMA) level should be followed by measurement of free T4 (and rarely also free T3) to distinguish between subclinical and overt hypothyroidism and hyperthyroidism. This policy would considerably reduce the number of in-vitro thyroid function tests without resulting in either a delay in diagnosis or a reduction in its accuracy.

Adolescent↗
PubMed1984

A sensitive immunoradiometric assay for serum thyroid stimulating hormone: a replacement for the thyrotrophin releasing hormone test?

The value as a thyroid function test of a new, rapid, and highly sensitive immunoradiometric assay for thyroid stimulating hormone (TSH) was assessed in 188 consecutive new patients with suspected hyperthyroidism. The diagnosis was made on clinical grounds and on the basis of serum total triiodothyronine and thyroxine concentrations and the response of TSH to thyrotrophin releasing hormone (TRH) as measured by radioimmunoassay. In all except one patient the basal TSH concentration by immunoradiometric assay predicted the response of TSH by radioimmunoassay to TRH, an undetectable value being recorded in patients with a subnormal response and a measurable value in those with a normal test result. This clear relation was not observed for basal TSH concentrations as measured by radioimmunoassay. In a series of 39 hospital inpatients with acute or chronic non-thyroidal illness, of whom 11 had low concentrations of total thyroxine or triiodothyronine, or both, basal TSH concentrations were detectable by both radioimmunoassay and immunoradiometric assay in all cases and were associated with normal responses to TRH. The immunoradiometric assay for TSH, which is commercially available, may therefore obviate the need for the more time consuming TRH test and simplify the approach to thyroid function testing in patients with suspected hyperthyroidism.

Adult↗
PubMed1983

[The migratory movements of young people who left English-language high schools in Quebec in 1971].

"The present article is an abridged version of the last of four reports on a longitudinal study of migratory movements, in and out of Quebec, of one cohort of young anglophones, those who left high school in Quebec in 1971." The data concern 975 individuals, who are a representative sample of those leaving English-language high schools in Quebec in 1971. The subjects were followed up in 1979 and again in 1982-1983. The results indicate that by 1982-1983, about 50 percent of those surveyed had left the province. (summary in ENG, SPA)

Americas↗