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PubMed2003

Thyroid dysfunction in elderly patients.

INTRODUCTION: The aim of this study was to determine the prevalence of thyroid dysfunction in an elderly in-patient population in a restructured hospital. METHODS: This was a prospective observational study performed on consecutive patients admitted into a geriatric ward in a restructured hospital in Singapore over a period of 3 months. Thyroid function tests (free thyroxine and thyroid stimulating hormone) were performed on all patients during routine blood screening. For those with abnormal thyroid function tests, further investigations including thyroid autoantibodies and anterior pituitary hormone measurements were performed where indicated. Demographic data, the presence of sepsis, hypoalbuminaemia and patients' functional status as well as other thyroid-related data were captured. RESULTS: A total of 184 patients were screened and 62 (33.7%) patients were found to have abnormal thyroid function tests. The mean age was 83.8 years (SD 6.2). Twenty (32.3%) were males and 42 (67.7%) were females. Thirty-three (53.2%) patients had sepsis on admission, 29 (46.8%) were functionally dependent and 22 (35.5%) had hypoalbuminaemia. The prevalence of thyroid disorders were as follows: 1 (0.5%), 4 (2.2%), 9 (4.9%), 15 (8.2%) and 33 (17.9%) patients had hyperthyroidism, subclinical hypothyroidism, primary hypothyroidism, secondary hypothyroidism and sick euthyroid syndrome, respectively. Cross-tabulating sick euthyroid syndrome against functional dependence, hypoalbuminaemia and sepsis did not reveal any significant association (Fisher's exact test, P = 0.44, P = 0.42 and P = 0.61, respectively). CONCLUSION: There was a high prevalence of thyroid dysfunction in the elderly in-patient population. We would advocate a lower threshold for screening elderly in-patients for thyroid dysfunction.

Aged↗
PubMed1996

Laboratory tests for thyroid disorders.

The evolution in thyroid function tests since the 1960s has improved the physician's proficiency in accurately identifying thyroid dysfunction in a patient with suspected thyroid disease. The mainstays of modern thyroid testing strategies are the serum TSH concentration and AMA (anti-TPO) titer. The TSH level serves as an endogenous indicator of the biologically active free T4 fraction and, as a result, is currently the best gauge of the thyroid status of an individual. In addition, the TSH level has other advantages over free T4 estimates in confirming the presence of thyroid disease. First, each individual has his or her own free T4-TSH setpoint, whereby any deviation from this genetically determined relationship changes the serum TSH level. Second, owing to the local nature of the T4 feedback at the pituitary, these alterations in serum TSH values amplify small changes in circulating free T4 values. The net result of these unique attributes of measuring TSH is the ability to detect thyroid dysfunction early in the course of thyroid disease. There are limitations to the use of a TSH determination as a single thyroid function test, however. They include the presence of hypothalamic or pituitary disease or concurrent nonthyroidal illness and the immediate treatment of either hyperthyroidism or hypothyroidism. Because the majority of thyroid diseases involves autoimmune processes of the thyroid gland, the inclusion of an AMA titer in any approach to thyroid testing enhances both the diagnostic and prognostic expertise of the physician. In conclusion, currently available thyroid function tests have enhanced the diagnostic skills of the physician, but their effectiveness relies on clinical judgment rather than guidance from protocol or random application.

Autoantibodies↗
PubMed1986

Are biochemical tests of thyroid function of any value in monitoring patients receiving thyroxine replacement?

To establish their role in monitoring patients receiving thyroxine replacement biochemical tests of thyroid function were performed in 148 hypothyroid patients studied prospectively. Measurements of serum concentrations of total thyroxine, analogue free thyroxine, total triiodothyronine, analogue free triiodothyronine, and thyroid stimulating hormone, made with a sensitive immunoradiometric assay, did not, except in patients with gross abnormalities, distinguish euthyroid patients from those who were receiving inadequate or excessive replacement. These measurements are therefore of little, if any, value in monitoring patients receiving thyroxine replacement. To stop doing thyroid function tests in these cases would result in considerable savings nationally in the cost of reagents in laboratories using commercial kits.

Adolescent↗
PubMed2004

Endocrine function in thai children infected with human immunodeficiency virus.

Most children infected by HIV show manifestations which mimic the clinical features of endocrine dysfunction, such as failure to thrive and hyperpigmentation. Our cross-sectional study was designed to assess the endocrine function of Thai children infected with HIV and to determine any relationship between disease severity, height and endocrine function. Thirty-six prepubertal children infected by HIV, 12 boys and 24 girls, aged 4-12 years (mean +/- SD 7 +/- 2 years), were tested for thyroid function (serum T4, T3, TSH and free T4), morning serum cortisol level, serum insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3). Disease severity was assessed using CD4+ T-lymphocyte percentage. Ten (28%) patients showed abnormal thyroid function. Five patients had euthyroid sick syndrome. Thyroid function tests indicated another five patients had a condition compatible with compensated hypothyroidism. Most patients had normal morning serum cortisol levels. Two-thirds and one-third of the patients showed low IGF-I and IGFBP-3 standard deviation scores (SDS), respectively. Twenty-six (72%) patients had CD4+ T-lymphocyte <15%, thus were classified as severely immune suppressed. A weak linear relationship was indicated between disease severity and endocrine function (r = -0.03 to 0.41). Statistical significance was found between CD4+ percentage and IGF-I SDS, IGFBP-3 SDS, serum T3 and free T4 (p-value = 0.03, 0.02, 0.02 and 0.01, respectively. Nearly half (44%) the patients were below the third percentile for height of Thai children. There was also a weak correlation between height SDS and endocrine function (r = -0.03 to 0.41). Statistical significance was observed between height SDS and IGF-I SDS, serum T3 and TSH (p-value = 0.02 and 0.01, respectively). We conclude that HIV-infected children with demonstrated growth failure and greater disease severity tend to have abnormal endocrine function, particularly disordered IGF-I levels.

Child↗
PubMed1975

In vitro testing of thyroid function: a review.

Triiodothyronine (T(3)) is the major thyroid hormone and thyroxine (T(4)) may be only a "prohormone". A normal serum T(3) concentration can compensate for a low serum T(4) to maintain euthyroidism and on the other hand hyperthyroidism can exist in spite of a normal T(4) if the T(3) concentration is increased ("T(3)-toxicosis"). A raised serum thyroid stimulating hormone (TSH) concentration is the present most sensitive indicator of thyroidal hypothyroidism and the level can be used to titrate replacement therapy to the individual's own requirements. TSH concentration is classically low in hypothyroidism secondary to pituitary or to hypothalamic disorder and synthetic thyrotrophin release hormone can then be used to identify which of these two sites is at fault. Thyroxine is the best form of thyroid replacement for hypothyroidism because it produces more consistently physiological concentrations of T(3). Full replacement is achieved with 0.1 - 0.2 mg of T(4)/day and doses above this, as formerly widely used, may cause over-replacement. New reliable kit tests are available which give in one quick procedure a measure of free-thyroxine even in the presence of abnormalities of protein-binding. These kit tests are suitable for the routine screening of the whole spectrum of thyroid dysfunction and when combined, in appropriate instances, with radioimmunoassay procedures for serum T(3) and TSH, provide a battery of tests which will help in the diagnosis of the great majority of causes of thyroid dysfunction.

Female↗
PubMed2000

From guidelines to hospital practice: reducing inappropriate ordering of thyroid hormone and antibody tests.

OBJECTIVE: Because of major technical improvements and conscious care about cost effectiveness, limiting the inadequate use of thyroid biological tests appears to be a major issue. DESIGN: To (i) estimate the ordering prevalence of each thyroid test, (ii) assess the prevalence of relevant thyroid tests, and (iii) evaluate the impact of expressing justification for tests during a 2-month intervention period on these prevalences. METHODS: During a prospective 2-month survey (June-July 1997), all the request forms were divided into four groups of prescription: (1) investigation of thyroid function, (2) taking drugs affecting the thyroid, (3) monitoring of nodule and cancer, and (4) investigation of thyroid autoimmunity. Their appropriateness was thus determined according to consensus in our hospital and previously published recommendations. Results were compared with those of retrospective similar 2-month periods in 1996 and 1998. Combinations of thyroid function tests and thyroid antibodies were analyzed during the 1996, 1997 and 1998 periods. RESULTS: The overall estimated rate of appropriate ordering between 1996 and 1997 increased from 42.5% to 72.4% (P<10(-4)), with a significant improvement in each group of main diagnosis referral, except in group 3 where suitability was always over 85%. However, in group 4, appropriateness remained low (36%). Combinations of thyroid tests revealed an increase in single TSH order forms and single autoantibodies to thyroperoxidase (TPOAb) ones, while TSH+free thyroxine+free tri-iodothyronine and TPOAb+ autoantibodies to thyroglobulin ones decreased significantly. Interestingly, all these changes were maintained 1 year later (June-July 1998) even though physicians were not aware of this new study. CONCLUSIONS: Persistent change in medical practice was thus assessed.

Autoantibodies↗
PubMed1981

Pharmacological interference with in vitro tests of thyroid function.

Numerous drugs may cause changes in the serum concentrations of T4 and of T3. If such alterations are not recognized an incorrect diagnosis may result. In moderate degrees of hypo- and hyperthyroidism thyroid hormone levels may be spuriously normal, or the influence of pharmacological substances may lead to false diagnosis of thyroid disease in euthyroid patients. Since prediction of such alterations remains uncertain, it may be necessary to perform additional investigations when a potential artefact is recognized. On the other hand many pharmacological agents, especially those which interact with neurotransmitters, may influence TSH secretion, too. The TRH-test may show an increase or decreased TSH response, although complete suppression is only rarely seen during high-dose glucocorticoid treatment when low TRH doses are applied. Because of TRH-test gives such wide separation between different clinical states false interpretations are generally less likely than with drug-induced changes in T4 and T3 values.

Alpha-Globulins↗