Beta-adrenergic blockade for the treatment of hyperthyroidism.

PURPOSE: To review the clinical and biochemical effects of beta-adrenergic blocking drugs on hyperthyroidism. MATERIALS AND METHODS: Studies published since 1972 were identified through a computerized search of MEDLINE and extensive searching of the bibliographies of the articles identified. Based on an understanding of the differences in beta-blocker metabolism in euthyroid and hyperthyroid patients, we reviewed the differences in pharmacokinetics and metabolic and clinical outcomes during their use in hyperthyroidism, as reported in the articles reviewed. RESULTS: beta Blockers have been used to modify the severity of the hyperadrenergic symptoms of hyperthyroidism for the past 20 years. The clinical efficacy of these agents is affected by hyperthyroid-induced alterations in their gastrointestinal absorption, hepatic metabolism, and renal excretion. The mechanisms whereby these clinical changes are effected is unknown. The agents differ in their beta 1 cardioselectivity, membrane-stabilizing activity, intrinsic sympathomimetic activity, and lipid solubility. They do not appear to alter synthesis or secretion of thyroid hormone by the thyroid gland. Their effects on thyroxine metabolism are contradictory. Decreased thyroxine to triiodothyronine conversion is caused by some, but not all, beta blockers, and this appears to correlate with membrane-stabilizing activity. There does not appear to be any alteration in catecholamine sensitivity during beta-adrenergic blockade. CONCLUSIONS: The principal mechanism of action of beta blockers in hyperthyroidism is to antagonize beta-receptor-mediated effects of catecholamines. beta Blockers are effective in treating hypermetabolic symptoms in a variety of hyperthyroid states. Used alone, they offer significant symptomatic relief. They are also useful adjuvants to antithyroid medications, surgery, and radioactive iodide treatment in patients with Graves' disease and toxic nodular goiters.

Diabetes care in health maintenance organizations.

An increasing amount of health care today is directed to the amelioration of chronic diseases for which there are no cures. Technological advances and the aging of the population have increased the costs of that care. In an attempt to control costs and increase the efficiency of health care, it is being increasingly delivered in alternate health-care systems where third-party payors influence the access, use, and quality of that care. This article traces the history of the development of alternative health-care delivery systems and describes how they attempt to deal with the tension between cost and quality in the context of the delivery of health care to people with diabetes. Systems for home health care, health education and dietary counseling, prescriptions and durable medical equipment, medical technology assessment, quality management, peer review, and cost containment in the various alternative health-care settings are described. Theoretically, the health maintenance organization offers an ideal system for delivering care that is accessible, affordable, and of good quality.

Pharmacokinetics and clinical effects of atenolol in therapy of hyperthyroidism.

The pharmacokinetics of atenolol and the effect of the drug on the clinical and laboratory features of hyperthyroidism were studied in 23 patients with hyperthyroidism. In the hyperthyroid state, the time to peak plasma concentration (Tmax) occurred significantly earlier, the elimination half-life was significantly shorter, and the areas under the curve were also significantly less compared to the euthyroid state, but there was no significant difference in peak plasma concentrations (Cmax) between these states. Administration of atenolol once daily resulted in marked clinical improvement in 2 to 4 weeks. The clinical index of thyrotoxic symptoms and signs decreased from 23.2 +/- 10.8 to 8.4 +/- 5.3 (p less than 0.005). Pulse similarly decreased significantly from 93.9 +/- 15.7 to 77.8 +/- 10.5. In contrast to the marked clinical improvement, there was no change in any of the serum concentrations of thyroid hormones T4, free T4, T3 and free T3 at the time of maximal clinical effect compared to pretreatment values. These data show that the beneficial effect of atenolol in hyperthyroidism is not due to changes in thyroid hormone metabolism.

A radioimmunoassay for measurement of thyronine and its acetic acid analog in urine.

A sensitive and specific RIA has been developed to measure thyronine (To) in urine. The RIA used an anti-To antibody obtained from a rabbit immunized with a L-To-human serum albumin conjugate and [3H]To as the radioligand. The acetic acid analog of To (ToAc), that is the diphenyl structure with an acetic acid side-chain, cross-reacted strongly with the antibody. Relative to To, it cross-reacted 160% in phosphate-buffered saline, pH 7.4, and 100% in 0.075 mol/L barbital buffer, pH 8.6, containing sodium salicylate (final concentration, 8 mg/mL). The latter conditions were employed for the RIA, and the results reported thus reflect the presence of To and/or ToAc. 3-Monoiodothyronine, 3'-monoiodothyronine, 3',5'-diiodothyronine, and 3,5-diiodothyronine cross-reacted with the anti-To antibody 1.9%, 1.7%, 0.3%, and 0.2%, respectively; the cross-reactivity of other To derivatives and tyrosine and its derivatives was less than 0.05%. Urinary To and/or ToAc excretion in 12 normal subjects averaged 16 +/- 2 (+/- SE) micrograms/day (59 +/- 9 nmol/day) or 14 +/- 2 micrograms/g creatinine (5.9 +/- 0.6 nmol/mmol creatinine). Treatment of urine from normal subjects with beta-glucuronidase or sulfatase did not significantly alter the To content. Column and thin layer chromatographic studies revealed that 83% and 61%, respectively (range, 37-100%), of urinary To immunoreactivity was attributable to ToAc. The mean daily excretion of To in 20 patients with nonthyroidal illness [NTI; 22 +/- 4 micrograms/day (82 +/- 17 nmol/day)] was similar to that in normal subjects, but was elevated when expressed as nanomoles per mmol creatinine (20 +/- 2; P less than 0.001), because creatinine excretion was reduced in the NTI patients. The mean daily urinary To excretion in 13 patients with hyperthyroidism due to Graves' disease was slightly elevated [29 +/- 6 micrograms/day (108 +/- 21 nmol/day); P less than 0.1], but was clearly elevated when expressed as nanomoles per mmol creatinine (37 +/- 8; P less than 0.001), again because creatinine excretion was reduced in these patients. The mean urinary To excretion was subnormal in 13 patients with hypothyroidism and was significantly (P less than 0.005) less than that in the NTI patients regardless of the manner in which the results were expressed. Analysis of pronase hydrolysates of thyroid glands obtained at autopsy from euthyroid patients suggested that the To content of the thyroid approximates only 1.2% that of T4, supporting the thesis that prior iodination of tyrosine is critical for the coupling process in the thyroid.(ABSTRACT TRUNCATED AT 400 WORDS)

Serum cortisol levels in Cushing's syndrome after low- and high-dose dexamethasone suppression.

To standardize the cutoff points of serum cortisol values in the evaluation of Cushing's syndrome during a low- and high-dose dexamethasone suppression test, daily serum cortisol measurements (0800 hours and 1600 hours) and urinary 17-hydroxycorticosteroids were compared (Study A). Forty-seven subjects were studied (11 normal subjects, 15 patients with Cushing's disease, five patients with adrenal adenoma, and 16 subjects with suspected Cushing's syndrome). A serum cortisol measurement at 1600 hours of more than 5 micrograms/dL on low-dose dexamethasone suppression and more than 10 micrograms/dL on high-dose dexamethasone were ascertained to be nonsuppressed values. A baseline dehydroepiandrosterone-sulfate value less than 0.4 microgram/mL indicated patients with an adrenocorticol adenoma. Study B was a prospective study of 17 patients in which no urine samples were collected. Serum cortisol levels, obtained in 1600 hours on the second day of low- and high-dose dexamethasone, accurately allowed a differential diagnosis of suspected Cushing's syndrome. Serum cortisol measurements can replace the urinary 17-hydroxycorticoid measurements in a cost-effective manner without a decrease in the degree of accuracy.

Treatment of hyperthyroidism with sodium ipodate (oragrafin) in addition to propylthiouracil and propranolol.

Ten patients with hyperthyroidism due to Graves' disease were treated with sodium ipodate (1 g daily) in addition to propranolol (P) plus propylthiouracil (PTU; 100 mg every 8 h) and were compared with a control group of 8 patients treated with P and PTU. Patients on P and PTU had a mean (+/- SEM) basal free T3 index of 387 +/- 59 (normal, 70--160) compared with that of 409 +/- 47 (P greater than 0.05) in the sodium ipodate group. The respective basal free T4 index values (normal, 4.5-10.9) were 21.3 +/- 2.8 for the controls and 25.9 +/- 2.8 for the ipodate group (P greater than 0.5), and the basal rT3 values were 192 +/- 49 and 210 +/- 41 (normal, 16--50 ng/dl; P greater than 0.05). The average percent changes in each thyroid index and rT3 were calculated. The first 3 days on P and PTU served as the basal period for the control group, and comparisons were made to the following 9 days. The ipodate group received P and PTU for 2.7 +/- 3.0 days, and comparisons were made with the interval on ipodate, P, and PTU (mean, 9.1 +/- 0.9 days). For the free T3 index, the control group showed a mean decrement of 20.5 +/- 4.4% compared with 50.2 +/- 3.1% for the ipodate group (P less than 0.001). The respective free T4 index decrements were 14.5 +/- 4.4% and 18.5 +/- 2.7% (P greater than 0.05). The respective changes in rT3 were -13.4 +/- 7.6% and +140 +/- 26.9% (P less than 0.001). In patients with hyperthyroidism, short term daily therapy with sodium ipodate plus P and PTU produces a greater reduction of free T3 index values than that caused by P and PTU alone.

Patterns off recovery of the hypothalamic-pituitary-thyroid axis in patients taken of chronic thyroid therapy.

To determine the patterns of recovery of the hypothalamic-pituitary-thyroid axis following long-term thyroid hormone therapy, TRH tests were performed on 8 euthyroid nongoitrous patients, 5 euthyroid goitrous patients, and 5 hypothyroid patients while they were taking full doses of thyroid hormone and 3, 7, 10, 14, 17, 21, 28, 35, 42, 49, and 56 days after stopping it. Serum TSH, T3, and T4 were measured before and at multiple intervals over a 4-h period after giving 500 mug TRH iv. In euthyroid non-goitrous patients, the mean duration of suppressed TSH response to TRH (maximum deltaTSH less than 8 muU/ml) was 12 +/- 4 (SE) days after stopping thyroid hormone and the mean time to recovery of normal TSH response to TRH (maximum deltaTSH greater than 8 muU/ml) was 16 +/- 5 days. None of the euthyroid nongoitrous patients ever hyperresponded to TRH; their average maximal deltaTSH was 24.5 +/- 2.2 muU/ml. Serum T4 fell below normal in 4 euthyroid non-goitrous patients, reaching lowest values at 4 to 28 days. While serum T4 was low, deltaTSH was subnormal. Normal increments of T4 and T3 after TRH occurred at 19 +/- 5 and 22 +/- 6 days, respectively. In the 5 goitrous patients, patterns of recovery of pituitary and thyroid function assessed by the same parameters were much less consistent. In the 5 hypothyroid patients, the mean duration of suppressed basal TSH and suppressed deltaTSH was 13 +/- 3 days; mean time to attain a supranormal basal TSH (greater than 8 muU/ml) was 16 +/- 4 days and to reach a supranormal deltaTSH (greater than 38 muU/ml) after TRH was 29 +/- 8 days. Following prolonged thyroid therapy in euthyroid patients, recovery of normal TSH responsiveness to TRH preceded recovery of the normal T3 and T4 response to TRH by 3 to 6 days. Basal serum TSH may be used to differentiate euthyroid from hypothyroid patients 35 days after withdrawal of thyroid therapy; the response to TRH does not improve this differentiation.

Propylthiouracil blocks extrathyroidal conversion of thyroxine to triiodothyronine and augments thyrotropin secretion in man.

Propylthiouracil (PTU) inhibits peripheral deiodination of thyroxine (T4) and triiodothyronine (T3) and decreases the metabolic effectiveness of T4 in animals. To assess the effect of PTU on extrathyroidal conversion of T4 to T3 in man, 15 studies were performed in athyreotic patients treated with 100 or 200 mug of L-T4 daily for 1 mo before the addition of PTU, 250 mg every 6 h for 8 days. serum T3, T4, and thyrotropin (TSH) were measured daily by radioimmunoassay; serum TSH response to 500-mug thyrotropin-releasing hormone (TRH) was measured before and on the last day of giving PTU. On the 100-mug LT4 dose, serum T3 fell from 120 plus or minus 5 (SE) to 83 plus or minus 6 ng/dl (P less than 0.005) with return to 113 plus or minus 5 ng/dl after stopping PTU; serum T4 (4.5 plus or minus 0.3 mug/dl) did not change. Similar results were seen in patients taking 200 mug of L-T4 daily. On the 100-mug dose of L-T4 the fall in T3 was accompanied by a reciprocal rise in serum TSH to 195 plus or minus 33% of initial concentration (P less than 0.01) with return to 104 plus or minus 8% after PTU. The serum TSH response to TRH (DELTAMUU/ml over base line) was greater during PTU therapy than during the control period. On 100-mug L-T4 DELTA TSH rose from 64 plus or minus 19 to 101 plus or minus 23 muU/ml (P less than 0.005). Expressed as percent of base-line TSH concentration, TSH rose from 140 plus or minus 52 to 280 plus or minus 44% (control vs. PTU) at 15 min, 265 plus or minus 72 to 367 plus or minus 63% at 30 min, 223 plus or minus 54 to 313 plus or minus 54% at 45 min, 187 plus or minus 45 to 287 plus or minus 51% at 60 min, and 145 plus or minus 22 to 210 plus or minus 28% at 120 min after TRH. The data suggest that PTU blocks extrathyroidal conversion of T4 to T3, thus increasing pituitary TSH secretion and augmenting the TSH response to TRH.