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Biomedical subjects

G S Kidd

Publications and source records attributed to G S Kidd.

At least 19 recordsLinked to original sources
PubMed1995

A longitudinal assessment of bone loss in women with levothyroxine-suppressed benign thyroid disease and thyroid cancer.

To determine if differing degrees of levothyroxine (LT4) suppression therapy for benign and malignant thyroid disease are associated with proportionately increased rates of bone loss, this longitudinal assessment of bone densitometry changes (single-photon and dual-photon absorptiometry) was conducted in three groups of subjects: 24 thyroid cancer patients who were treated with near-total thyroidectomy, radioiodine ablation, and aggressive LT4-suppression; 44 patients who were treated with more conservative LT4-suppression for benign thyroid disorders; and 24 normal controls. Bone densitometry values were adjusted for age, weight, height, and menopausal status. The rates of bone loss in benign LT4-suppressed patients were greater than those in controls at the midradius, distal radius, lumbar spine, and femoral neck. The rates of loss in the thyroid cancer patients were also greater than those in the controls at all four sites and greater than in the benign LT4-suppressed patients at the midradius, distal radius, and femoral neck but not in the lumbar spine. Rates of bone loss were not significantly correlated with LT4 dose or with the serum level of T4 or TSH. LT4-suppression therapy for benign thyroid disease is associated with accelerated bone loss. More aggressive LT4-suppression for thyroid cancer is associated with even greater bone loss, particularly in cortical bone regions. These risks must be weighed against the benefits of LT4 therapy in individual patients.

Bone Density↗
PubMed1994

Effects of mild asymptomatic primary hyperparathyroidism on bone mass in women with and without estrogen replacement therapy.

Primary hyperparathyroidism (HPT) presents most commonly as a mild elevation of the serum calcium concentration in an asymptomatic individual. There are conflicting data regarding the effects of mild primary HPT on bone mass. This cross-sectional study was conducted to examine this question further and to determine whether estrogen replacement therapy (ERT) in postmenopausal women with primary HPT might be beneficial. We measured bone mass in 59 women with mild asymptomatic primary HPT, of whom 43 (HPT) had never taken and 16 (estrogen-replaced HPT) were currently taking ERT. We also studied 84 healthy normocalcemic women who were not on ERT (controls) and 45 who were on ERT (estrogen-replaced controls). After adjustment for age, height, and weight, mean bone mass values in the HPT group were significantly reduced in the midradius (20%), distal radius (20%), lumbar spine (17%), and femoral neck (11%) compared with the controls. The estrogen-replaced HPT group had mean bone mass values greater than those in the HPT group, similar to those in the controls, and lower than those in the estrogen-replaced controls. Mild asymptomatic primary HPT results in bone loss from both the appendicular and axial skeleton, and ERT in postmenopausal women with primary HPT may ameliorate this loss.

Aged↗
PubMed1993

An iodine load from water-purification tablets alters thyroid function in humans.

Tablets containing tetraglycine hydroperiodide are used to purify small quantities of water for drinking. Because short-term administration of stable iodide can alter thyroid function in normal adults, we evaluated the effects of these tablets on thyroid function during a military field training exercise. Fourteen normal volunteers participated in the study. After an adjustment period of 2 weeks to the field environment, half of the subjects received four dissolved water-purification tablets (32 mg free iodine) daily for 7 consecutive days while the other half served as controls. At the end of the study the treatment group showed reductions in the mean serum levels of thyroxine (14%) and total triiodothyronine (15%) and significant increments in basal thyrotropin (TSH) (122%) and the TSH response to thyrotropin-releasing hormone (49%) compared to baseline values. The basal TSH level rose above the normal range in two subjects. No significant changes in any parameter of thyroid function were observed in the control subjects. One week of daily exposure to the iodine load from four tetraglycine hydroperiodide water-purification tablets causes mild impairment of thyroid function in humans.

Adolescent↗
PubMed1992

Lack of prostaglandin effect on sodium balance and hyperreninemia in adrenalectomized rats.

Glucocorticoids are known inhibitors of prostaglandin production. Prostaglandin E2 (PGE2) and prostacyclin (PGI2) are promoters of natriuresis and renin release. Excessive prostaglandin production, therefore, might contribute to the altered sodium balance and renin release observed in primary adrenal insufficiency. To test this hypothesis, sodium balance and prostaglandin production were measured in adrenalectomized rats and in animals receiving prostaglandin inhibitors or replacement dexamethasone. Compared to sham-operated controls, adrenalectomized rats had decreased two-day sodium balance and elevated plasma renin concentration (PRC), renal PGE2 production, and renal 6-ketoprostaglandin F1 alpha (6kPGF1 alpha, the nonenzymatic metabolite of PGI2); however, no appreciable change in aortic 6kPGF1 alpha production was observed. Dexamethasone given to adrenalectomized rats normalized PRC but had no effect on sodium balance or prostaglandin production. Likewise, prostaglandin inhibitors did not alter the sodium balance or decrease the PRC post adrenalectomy. These data confirm renal prostaglandin production is increased in adrenalectomized rats, but suggest that the elevation is not due directly to glucocorticoid deficiency. Further, PRC levels in adrenal insufficiency do not appear to be prostaglandin mediated. In conclusion, excessive renal prostaglandin production does not contribute to altered sodium balance or increased PRC in adrenalectomized rats.

Adrenal Glands↗
PubMed1992

Case report: a glucose responsive insulinoma--implication for the diagnosis of insulin secreting tumors.

Normal insulin secretagogues, including glucose, usually have little influence on insulin secretion from insulinomas. Therefore, insulinomas typically cause fasting hypoglycemia with relative hyperinsulinemia. This report describes a patient with hyperinsulinemia due to an islet cell adenoma with microadenomatosis, which, upon provocative in vivo testing, was found to be profoundly responsive to hypoglycemic and hyperglycemic stimuli. A 72 hr fast followed by brisk exercise resulted in a gradual reduction of serum glucose and insulin concentrations, but did not provoke symptomatic hypoglycemia. Oral glucose tolerance testing resulted in a prompt 10-fold increase in serum insulin accompanied by a mildly symptomatic and gradual fall in serum glucose to 30 mg/dl 90 minutes after glucose ingestion. An intravenous glucose challenge caused an acute increase in serum insulin to more than 1200 microU/ml with a resulting serum glucose of 11 mg/dl 25 minutes later, associated with loss of consciousness. Although a prolonged fast has proven to be the best diagnostic test for insulin secreting tumors, many other provocative tests that use normal insulin secretagogues have been somewhat useful in this regard. The patient in this report supports the concept that insulinomas vary widely in their response to a number of normal physiologic regulators of insulin secretion, including the serum glucose concentration. A variety of provocative tests may be needed to fully evaluate the rare patient in whom there is a strong clinical suspicion of insulinoma but who has a nondiagnostic prolonged fast.

Blood Glucose↗
PubMed1992

The clonidine suppression test for pheochromocytoma. A review of its utility and pitfalls.

OBJECTIVE: The intent of this study is to retrospectively evaluate our experience, as well as all published information, regarding the clonidine suppression test to determine its utility, accuracy, and safety in the diagnosis of pheochromocytoma. PATIENTS AND METHODS: All 22 patients (including four with pheochromocytoma) evaluated at a major military referral hospital with the clonidine suppression test for suspected pheochromocytoma for more than 6 years were retrospectively reviewed. All published series of patients similarly evaluated were also critically reviewed. RESULTS: All studies confirm that a nonstressed plasma norepinephrine of more than 2000 pg/mL is diagnostic of pheochromocytoma. In those patients with a plasma norepinephrine of less than 2000 pg/mL, the clonidine suppression test is 92% accurate in diagnosing pheochromocytoma when the normal response to clonidine is defined as total plasma catecholamines of less than 500 pg/mL. Its accuracy diminishes in patients with low baseline plasma catecholamine levels, who may better be tested with a stimulatory test (ie, glucagon). The use of diuretics, beta-blockers, and antidepressants may cause false-positive results or severe hypotension during the clonidine suppression test. Those previously treated with clonidine or with baroreceptor dysfunction may also be prone to severe hypotension, but this complication is otherwise uncommon after acute clonidine ingestion. CONCLUSION: Although it is rarely necessary for the diagnosis of pheochromocytoma, the clonidine suppression test is an accurate and safe test in a select group of patients.

Adrenal Gland Neoplasms↗
PubMed1991

Crossover comparison of maximum dose glyburide and glipizide.

Patients with non-insulin-dependent diabetes mellitus (NIDDM) failing to respond to therapy with a maximum dose of glyburide (GB) or glipizide (GZ) are often given a trial of the alternate second-generation sulfonylurea (SGS) before insulin therapy is considered. The efficacy of this therapeutic maneuver has not been thoroughly tested. We studied 26 subjects with fasting serum glucose (FSG) levels greater than 8.3 mmol/L (150 mg/dL) despite maximum doses of either GB (20 mg/day) or GZ (40 mg/day). Group 1 consisted of 16 subjects taking GB (mean FSG = 12.7 mmol/L [228 mg/dL]) and group 2 included 10 subjects taking GZ (mean FSG = 13.0 mmol/L [234 mg/dL]). Subjects continued taking their original SGS for 8 weeks then switched to a maximum dose of the alternate agent for an additional 8 weeks. Values for FSG, hemoglobin A1c, and lipids were recorded before the study and after 8 weeks on each SGS trial. No significant changes were noted for any variable in either group. When maximum dose GB therapy was compared to maximum dose GZ therapy in the combined study group (n = 26), no advantage was noted for either agent. We conclude that metabolic control in NIDDM patients failing to respond to therapy with maximum dose GB or GZ is not improved by switching to the alternate SGS.

Blood Glucose↗
PubMed1991

Reduced bone-mineral content is a risk factor for hip fractures.

To evaluate skeletal osteopenia as a risk factor for hip fractures, we measured bone-mineral content in 18 postmenopausal women (aged 50 to 85 years) within 5 days of sustaining a nontraumatic hip fracture. We compared these findings to those in 50 women without a hip fracture who were matched for age, postmenopausal years, height, and weight to the study participants. With the use of dual-photon absorptiometry, the hip fracture patients were found to have a significantly reduced mean bone-mineral content (P less than .005) at three sites in the unaffected hip and a marginally lower mean value (P less than .057) in the lumbar spine as compared to the controls. Other findings in the fracture group included a history of little physical activity, diminished visual acuity, and a somewhat high prevalence of psychiatric/organic brain disorders. Reduced bone mass is an important risk factor for hip fractures. However, other conditions such as physical inactivity, reduced visual acuity, and cognitive impairment may also affect the tendency to fall and/or the ability to cushion the impact of a fall and thus further increase the risk of fracture occurrence.

Accidental Falls↗
PubMed1990

The effects of theophylline and nifedipine on corticotropin-stimulated cortisol secretion.

The adrenal cortisol response to corticotropin appears to involve both calcium and cyclic adenosine 3',5'-monophosphate (cAMP) as intracellular mediators. In 10 healthy male volunteers, the short-term administration of theophylline, which affects both intracellular calcium and cAMP, lowered basal cortisol levels but augmented the in vivo cortisol response to short-term corticotropin stimulation. Short-term administration of nifedipine, a calcium channel antagonist, had no effect on basal or peak cortisol levels but reduced the incremental cortisol response to corticotropin. The effects of both theophylline and nifedipine, although statistically significant, were modest and of questionable clinical significance but should be considered in the interpretation of the clinical corticotropin stimulation test. They may also provide some insight into the post-receptor actions of corticotropin.

Adrenal Cortex↗
PubMed1990

Tamoxifen therapy for painful idiopathic gynecomastia.

We have evaluated the efficacy of the antiestrogen tamoxifen in six men with painful idiopathic gynecomastia. Subjects were given either tamoxifen or placebo for 2 to 4 months and then were given the other agent for an identical period. Breast size was considered to have been reduced only if it had decreased by one or more Marshall-Tanner stages during the treatment period. Pain reduction with tamoxifen therapy was statistically significant for the group, occurring in five of six subjects during tamoxifen treatment and in only one of six during the placebo period. Size reduction with tamoxifen was only marginally significant for the entire group, but occurred in all three subjects who were initially in Marshall-Tanner stage III and in none of the three subjects who were initially in stage V. During tamoxifen treatment, there was a significant increase in the serum levels of luteinizing hormone and total estradiol and a marginally significant increment in the total testosterone level.

Adult↗
PubMed1990

Evidence of endocrine involvement early in the course of human immunodeficiency virus infection.

Adrenal, gonadal, and thyroid function were assessed in 40 asymptomatic subjects in whom infection with the human immunodeficiency virus (HIV) had recently been documented. None of the patients had historical or clinical evidence of endocrine dysfunction. Their mean serum hormone levels were also within the expected ranges, but several differences were noted compared to those of seronegative controls. Basal cortisol, basal aldosterone, and ACTH-stimulated cortisol were significantly lower in the HIV group. One subject (2.5%) had a subnormal cortisol response, and two (5%) had abnormal aldosterone responses to ACTH. PRA tended to be higher, and serum angiotensin-converting enzyme levels somewhat lower in the HIV group. Serum free testosterone was markedly elevated in the HIV patients and was associated with an exaggerated LH response to GnRH, but PRL, estradiol, and basal and peak GnRH-stimulated FSH did not differ between groups. Three subjects (8%) had subclinical hypothyroidism. Serum thyroid hormone levels were normal, but basal T3 was lower in the HIV group compared to control values. While of little immediate clinical importance, many subtle endocrine aberrations are evident very early in the course of HIV infection. These findings obtained in HIV-seropositive subjects without infections or tumors and who were not receiving medical therapy suggest an effect of HIV on each of the endocrine systems examined.

Adrenal Cortex Function Tests↗
PubMed1990

Antideoxyribonucleic acid antibodies in Graves' disease.

Antidouble stranded DNA (dsDNA) antibodies have been detected by a sensitive RIA in the sera of 28-100% of patients with Graves' disease, but it remains unclear whether these assays have detected authentic dsDNA antibodies. We have obtained sera from 42 patients with active Graves' disease and no known connective tissue disorders. All sera were tested for dsDNA antibodies by 2 quantitative RIAs (Farr assay and Millipore filter assay; normal, less than 20% for both assays) and by an enzyme-linked immunosorbant assay for antibodies to dsDNA and to single stranded DNA (ssDNA). All sera were negative for dsDNA antibodies by the Farr assay and by enzyme-linked immunosorbant assay, 2 of 42 had mildly elevated levels (33% and 23%) by the Millipore filter assay, and 7 of 42 were positive for ssDNA antibodies. The 2 positive sera for dsDNA antibodies were also tested using the Crithidia luciliae indirect immunofluorescence assay, and both were negative. Patients with Graves' disease have been reported to have an increased prevalence of antinuclear antibodies, but the more recent findings of dsDNA antibodies in these patients is of interest because dsDNA antibodies are considered to be specific for systemic lupus erythematosus. Our data suggest that true immunoglobulin G dsDNA antibodies are not elevated during active Graves' disease, and positive assay results may be due to measurement of ssDNA antibodies, immunoglobulin M dsDNA antibodies, or nonantibody DNA binding.

Adolescent↗
PubMed1990

Effects of a continuous thyrotropin-releasing hormone infusion on gonadotropin-releasing hormone-stimulated gonadotropin secretion.

We examined the effects of elevated thyrotropin-releasing hormone (TRH) levels on the gonadotropin response to gonadotropin-releasing hormone (GnRH) in 16 healthy men. A TRH infusion, which was begun 15 minutes before and continued for 120 minutes after the bolus administration of GnRH, was compared with a saline infusion. During the TRH infusion the gonadotropin responses to acute GnRH stimulation were higher than in the saline control period but, although statistically significant, the differences were small in magnitude and were similar to the intraindividual coefficient of variation in gonadotropin responses determined under control conditions. They did not appear to be of clinical significance. TRH significantly lengthened the interval between GnRH administration and the appearance of peak gonadotropin levels. These results indicate that a brief TRH infusion, producing mild elevations of thyrotropin and prolactin, causes slight alterations predominantly in the timing of GnRH-stimulated gonadotropin secretion.

Adult↗
PubMed1989

Massive extracapsular hemorrhage from a parathyroid cyst.

A 32-year-old man had a giant cervical mass, dysphagia, dyspnea, and severe hypercalcemia. A computed tomographic scan showed the mass to extend from the left mandible to the level of the aortic arch. Exploratory surgery of the neck revealed a ruptured parathyroid cyst complicated by massive hemorrhage into the cervical tissues and mediastinum. The postoperative course was uncomplicated with prompt resolution of the hypercalcemia. Although a rare occurrence, extracapsular parathyroid hemorrhage should be considered in the differential diagnosis of all rapidly evolving cervical and mediastinal masses, especially when hypercalcemia is present.

Adult↗
PubMed1989

Gallium-67 uptake by the thyroid associated with progressive systemic sclerosis.

Although thyroidal uptake of gallium-67 has been described in several thyroid disorders, gallium-67 scanning is not commonly used in the evaluation of thyroid disease. Thyroidal gallium-67 uptake has been reported to occur frequently with subacute thyroiditis, anaplastic thyroid carcinoma, and thyroid lymphoma, and occasionally with Hashimoto's thyroiditis and follicular thyroid carcinoma. A patient is described with progressive systemic sclerosis who, while being scanned for possible active pulmonary involvement, was found incidentally to have abnormal gallium-67 uptake only in the thyroid gland. Fine needle aspiration cytology of the thyroid revealed Hashimoto's thyroiditis. Although Hashimoto's thyroiditis occurs with increased frequency in patients with progressive systemic sclerosis, thyroidal uptake of gallium-67 associated with progressive systemic sclerosis has not, to our knowledge, been previously described. Since aggressive thyroid malignancies frequently are imaged by gallium-67 scintigraphy, fine needle aspiration cytology of the thyroid often is essential in the evaluation of thyroidal gallium-67 uptake.

Biopsy, Needle↗