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P Bacharach

Publications and source records attributed to P Bacharach.

11 recordsLinked to original sources
PubMed1994

Low serum thyrotropin concentrations as a risk factor for atrial fibrillation in older persons.

BACKGROUND: Low serum thyrotropin concentrations are a sensitive indicator of hyperthyroidism but can also occur in persons who have no clinical manifestations of the disorder. We studied whether low serum thyrotropin concentrations in clinically euthyroid older persons are a risk factor for subsequent atrial fibrillation. METHODS: We studied 2007 persons (814 men and 1193 women) 60 years of age or older who did not have atrial fibrillation in order to determine the frequency of this arrhythmia during a 10-year follow-up period. The subjects were classified according to their serum thyrotropin concentrations: those with low values (< or = 0.1 mU per liter; 61 subjects); those with slightly low values (> 0.1 to 0.4 mU per liter; 187 subjects); those with normal values (> 0.4 to 5.0 mU per liter; 1576 subjects); and those with high values (> 5.0 mU per liter; 183 subjects). RESULTS: During the 10-year follow-up period, atrial fibrillation occurred in 13 persons with low initial values for serum thyrotropin, 23 with slightly low values, 133 with normal values, and 23 with high values. The cumulative incidence of atrial fibrillation at 10 years was 28 percent among the subjects with low serum thyrotropin values (< or = 0.1 mU per liter), as compared with 11 percent among those with normal values; the age-adjusted incidence of atrial fibrillation was 28 per 1000 person-years among those with low values and 10 per 1000 person-years among those with normal values (P = 0.005). After adjustment for other known risk factors, the relative risk of atrial fibrillation in elderly subjects with low serum thyrotropin concentrations, as compared with those with normal concentrations, was 3.1 (95 percent confidence interval, 1.7 to 5.5; P < 0.001). The 10-year incidence of atrial fibrillation in the groups with slightly low and high serum thyrotropin values was not significantly different from that in the group with normal values. CONCLUSIONS: Among people 60 years of age or older, a low serum thyrotropin concentration is associated with a threefold higher risk that atrial fibrillation will develop in the subsequent decade.

Age Factors↗
PubMed1991

Low serum thyrotropin (thyroid-stimulating hormone) in older persons without hyperthyroidism.

We studied a large population (n = 2575) of unselected ambulatory persons older than 60 years to determine the prevalence of a low serum thyroid-stimulating hormone (TSH) level, ie, of less than 0.1 mU/L using a sensitive assay, a level suggestive of hyperthyroidism in younger adults. One hundred one persons (3.9%) had a low serum TSH level. About half of them (51/101) were taking thyroid hormone. Of the remainder, 44 were not hyperthyroid did not become so during up to 4 years of follow-up. Forty-one of the 44 euthyroid persons had a serum thyroxine level of less than 129 nmol/L; repeated testing showed a serum TSH level of more than 0.1 mU/L in the three euthyroid persons with a serum thyroxine level of more than 129 nmol/L. Only six were hyperthyroid or became so during the follow-up period; all had a serum thyroxine level of more than 129 nmol/L. Routine clinical examination was not a sensitive indicator of hyperthyroidism and did not permit discrimination from euthyroidism. A low value of serum TSH alone, while it had high sensitivity and specificity for hyperthyroidism, had a low positive predictive value (12%) for this diagnosis; addition of the thyroxine assay raised the predictive value fivefold to 67%. A low value of serum TSH is far more common in older persons than is hyperthyroidism. Low values in euthyroid persons are accompanied by a clearly normal serum T4 concentration (less than 129 nmol/L) or by a serum TSH level of more than 0.1 mU/L on repeated testing. We recommend measurement of the serum TSH thyroid concentration, using a sensitive assay, as the initial step in testing any older person for possible hyperthyroidism. Measurement of the serum T4 concentration or the free T4 index on the same sample would be needed only in the approximately 2% with a serum TSH level of less than 0.1 mU/L; alternatively, the TSH assay in these could be repeated at a later time.

Aged↗
PubMed1989

The aging thyroid. The use of thyroid hormone in older persons.

The overall prevalence of thyroid hormone use in an unselected population of older adults (n = 2575; average age, 68.6 years) was 6.9% (10.0% in women and 2.3% in men). Eighty-one percent of women taking it were doing so for appropriate indications, eg, hypothyroidism, while 12% were not, eg, for obesity or high serum cholesterol; more men (29%) were taking it inappropriately. Inappropriate use was associated with desiccated thyroid more than with thyroxine. After follow-up averaging 6.9 years, 58% of inappropriate users were still taking it. Underuse also occurred. Thirty-seven percent of those definitely hypothyroid had a clearly elevated serum thyrotropin level (greater than 10 mU/L) despite thyroid therapy. Thyroid therapy is common in the elderly; most is appropriate. When inappropriate use occurs, it is more common in men and more often associated with desiccated thyroid, still commonly used in this age group. In chronic users of thyroid hormone, it is important to review currently appropriate indications and to measure serum thyrotropin levels to assess the adequacy of treatment of primary hypothyroidism.

Age Factors↗
PubMed1989

Serum prolactin and aging: basal values and changes with estrogen use and hypothyroidism.

We studied basal serum prolactin in older (greater than age 50) men (N = 501) and women (N = 384) using younger adults for comparison and excluding those taking medications. Serum prolactin rose slightly with increasing age in men; it fell slightly in women until age 80, when it rose slightly. Men and women were not different except for the higher value in women at age 20 to 29. Serum prolactin did not fall after the menopause, while estrogen treatment had no effect on older women and caused only a slight rise in older men. Thyroid deficiency had only a minimal effect and did not raise the serum prolactin above 25 ng/ml. The prevalence of clearly elevated values (greater than 20 ng/ml) was only 1.3% in women and 0.6% in men above age 50; there is little evidence for a significant prevalence of prolactin-secreting adenomata in older persons. In older persons, prolactin-secreting tumors are uncommon, and neither thyroid failure nor estrogen therapy are good explanations for a clearly elevated serum prolactin.

Adult↗
PubMed1985

The aging thyroid. Relationship between elevated serum thyrotropin level and thyroid antibodies in elderly patients.

The relationship of thyroid antibodies and the serum level of thyrotropin in older adults (over age 60) was studied to determine whether thyroid antibodies were a good clue to thyroid failure in elderly persons. Of those with thyroid failure, evidenced by clearly elevated serum thyrotropin values (more than 10 microU/ml), 67 percent had positive antimicrosomal antibody levels, a prevalence much greater (p less than 0.001) than that among those of comparable age with normal thyroid function (18 percent). Nevertheless, one third (33 percent) had thyroid failure without positive antimicrosomal antibody levels; this was true whether or not a low serum thyroxine value was present. Furthermore, of those with positive antimicrosomal antibody levels, most (68 percent) did not have thyroid failure. Thus, although positive antimicrosomal antibody levels occurred more often in elderly patients with thyroid failure than in those with normal thyroid function, a sizable fraction of those with thyroid failure did not have positive antimicrosomal antibody levels. Hence, measurement of thyroid antimicrosomal antibodies is not a good test of early thyroid failure in older patients; direct demonstration of a clearly elevated serum thyrotropin value is a better approach.

Adult↗
PubMed1985

The aging thyroid. Thyroid deficiency in the Framingham Study.

In an unselected population of elderly (over age 60 years) men and women (the original cohort of the Framingham Study), the prevalence of thyroid deficiency, evidenced by a clearly elevated serum thyrotropin (TSH) level (greater than 10 microU/mL), was 4.4%. Women had thyroid deficiency (5.9%) more often than men (2.3%). Of those with clearly elevated serum TSH levels, only 39% had low serum thyroxine (T4) levels; the remainder had serum T4 levels in the lower half of the normal range. Others (5.9%) had a slightly elevated serum TSH level (5 to 10 microU/mL); their status was not clear, but more (12.7%) had low T4 levels than expected. The level of serum T4 was not a sensitive measure of thyroid deficiency nor was routine examination by a physician, even when the patient's background contained a clue to a possible thyroid problem. An elevated serum TSH level was a sensitive marker of thyroid deficiency in the elderly and was often the only way to detect it. Further studies are needed to determine the relationship of thyroid deficiency to cognitive and cardiovascular function in older persons.

Aged↗
PubMed1979

The aging thyroid. Increased prevalence of elevated serum thyrotropin levels in the elderly.

Of 344 relatively healthy persons older than 60 years, 22 (5.9%) had a clearly elevated level of serum thyrotropin (TSH) (greater than 10 muU/mL), a finding more common in women than in men. Ten of the 22 had low values for serum thyroxine (T4) and free T4 (FT4) index, but only one had a low value for serum triiodothyronine (T3) or free T3 (FT3) index. A further 14.4% had a slightly elevated level of serum TSH (greater than 5 less than or equal to 10 muU/mL), but none had low values for serum T4 or FT4 index. Age alone has little effect on the measurements of T4; age is associated with slightly lower T3 levels, but only in men 60 years or older or in women 80 years or older. Longitudinal studies should determine if a slightly elevated serum TSH rises further with age and if there is a causal relationship between a high level of serum TSH and cardiovascular disease.

Aged↗
PubMed1978

The relationship of changes in serum estradiol and progesterone during the menstrual cycle to the thyrotropin and prolactin responses to thyrotropin-releasing hormone.

The responses of serum TSH and PRL to TRH (500 microgram) were studied in normal young women in the early follicular, periovulatory, and midluteal phases of the menstrual cycle in order to examine the relationship of these responses to the levels of estradiol relationship of these responses to the levels of estradiol (E2) and progesterone. Each woman was studied twice in each phase in order to assess intraindividual variability. There was no significant difference in either the TSH or PRL responses among the phases of the menstrual cycle nor was either response affected by the periovulatory rise in E2 or by the luteal rise in both E2 and progesterone. Thus, the interpretation of the TSH and PRL responses to TRH in normal women is not affected by the menstrual cycle although both responses are greater in women that in men. Both the peak TSH and peak PRL after TRH were highly correlated with the basal levels of TSH (r = 0.85; P less than 0.01) and PRL (r = 0.67; P less than 0.01), respectively, indicating that the TSH and PRL responses to TRH in women are directly proportionate to the basal levels of the respective hormones, as previously shown for the TSH response in men. The mean intraindividual variability (coefficient of variation) of the TSH response to TRH was 18%, but ranged as high as 56%, while that of the PRL response was 16% and ranged up to 31%; variability was not affected by the phase of the menstrual cycle. The normal range of the peak TSH after TRH in women is 7-33 microU/ml (mean +/- 2 SD); however, because of the variability, a normal woman may sometimes have a peak TSH after TRH as low as 4 microU/ml. Repeating the test will result in a normal value if the woman is truly normal. Similarly, the normal peak PRL after TRH in women is 22-111 ng/ml (mean +/- 2 SD); usually, however, the lower limit is 30 ng/ml with lower values due to intraindividual variation. The data suggest that the higher average level of E2 in women compared to women, but that the cyclic changes in serum E2 or progesterone in women have little or no additional effect.

Adult↗