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Biomedical subjects

M S Croxson

Publications and source records attributed to M S Croxson.

At least 19 recordsLinked to original sources
PubMed1992

A novel variant of transthyretin (prealbumin), Thr119 to Met, associated with increased thyroxine binding.

A group of patients with prealbumin associated hyperthyroxinemia possess a common single base substitution in the fourth exon of their transthyretin gene. This cytosine to thymine substitution occurs in the codon for residue 119 and results in the predicted replacement of a threonine residue with a methionine at this position. A new NcoI restriction endonuclease cleavage site is created by the point mutation and can be detected by a rapid and simple assay based on the polymerase chain reaction. This variant transthyretin is inherited in an autosomal dominant manner and is apparently not amyloidogenic but is associated with increased thyroxine binding. As healthy heterozygous individuals have normal serum thyroxine concentrations, the hyperthyroxinemia sometimes found may not be primarily due to the variant.

Base Sequence↗
PubMed1988

Treatment of metastatic prostate carcinoma with the depot LRH analog Zoladex.

A long-acting LRH agonist (ICI 118630, Zoladex) was given by monthly subcutaneous injection to 25 patients with previously untreated symptomatic advanced prostatic carcinoma. The medication was well tolerated with the only side effect being hot flushes in 15 patients. Subjective improvement occurred in 22 patients, and disease remission or stabilization judged by objective criteria was seen in 21 and 18 patients from the total group at 3 and 6 months of treatment, respectively. Twelve of 18 patients followed for 1 year were still in objective remission/stabilization. Prostate volume measured by ultrasound decreased by a mean value of 75% and urine flow increased significantly. There were significant falls in serum testosterone and gonadotrophin levels and significant although lesser reductions in serum androstenedione and dehydroepiandrosterone. These changes were accompanied by significant reductions in serum acid and alkaline phosphatase and a rise in serum osteocalcin. Four patients (16%) experienced an initial tumor flare. Although only a small number of patients were studied, Zoladex appeared to be a well-tolerated agent for treatment of prostatic carcinoma, with an initial clinical response similar to that seen with standard endocrine therapy.

Adult↗
PubMed1988

Zoladex treatment of symptomatic prostatic carcinoma.

The depot LH-RH agonist Zoladex was used to treat 38 patients with previously untreated symptomatic stage D2 prostate carcinoma. Side effects were minimal and patient acceptability excellent, although temporary tumor flare occurred in 11% of patients. Eighty-four percent experienced subjective improvement and 87% had objective evidence of initial disease stabilization or remission lasting 3 months. Serum levels of gonadotrophin and free testosterone as well as androgens of adrenal origin fell significantly with treatment. Long-term survival to date appears at least as good as that described for conventional endocrine therapy.

Buserelin↗
PubMed1987

Disopyramide-induced hypoglycaemia and increased serum insulin.

A patient treated with disopyramide presented with hypoglycaemia, a raised serum insulin level and died of pneumonia. From these findings and a review of 10 case reports, we propose that disopyramide causes hypoglycaemia by stimulation of insulin release as described for the antimalarial drugs quinine and quinidine.

Aged↗
PubMed1987

Adrenocortical carcinoma presenting as primary aldosteronism in a young man.

A young Polynesian man presented with severe hypertension complicated by an intracerebral hemorrhage. The hypertension was found to be secondary to hyperaldosteronism from a well differentiated adrenocortical carcinoma. Surgical removal of the tumor has resulted in a near normal blood pressure with no evidence of tumour recurrence of hyperaldosteronism after one year.

Adrenal Cortex Neoplasms↗
PubMed1986

Admission thyroid function testing in elderly patients.

The free thyroxine index (FTI) was measured in 307 elderly patients admitted to two geriatric units. The initial FTI was abnormal in 41 (13.3%), being raised in 27 and low in 14 patients. On further testing, these abnormalities were found to be either transient or of no clinical significance in 36 of the 41 patients (88%). Only five of the 307 patients (1.6%) were finally treated for previously undiagnosed thyroid disease and of these three improved (1%). Thyroid disease identified by routine screening, and not suspected from the history and clinical findings, was present in only two patients (0.7%). In view of these findings we suggest that thyroid screening is no more justified in the elderly than in younger hospitalised patients.

Aged↗
PubMed1985

Detection of familial dysalbuminaemic hyperthyroxinaemia.

A simple test of in vitro thyroxine binding to serum proteins was used to screen serum samples from euthyroid patients with unexplained increases in the free thyroxine index. A diagnosis of familial dysalbuminaemic hyperthyroxinaemia was presumed in 14 unrelated subjects and six first degree relatives. Increased binding of thyroxine to thyroxine binding prealbumin was diagnosed in one woman with four unaffected relatives. Seven patients with familial dysalbuminaemic hyperthyroxinaemia had been treated for presumed thyrotoxicosis: two had typical Graves' disease and one subacute thyroiditis. Four other patients had been mistakenly treated with radioactive iodine or antithyroid drugs. In previously treated patients familial dysalbuminaemic hyperthyroxinaemia was suspected from the combination of a high serum thyroid stimulating hormone concentration and a normal but invalid free thyroxine index. Physicians should be cautious in accepting a diagnosis of thyrotoxicosis based mainly on a raised serum thyroxine concentration.

Adolescent↗
PubMed1985

The screening of patients with suspected thyrotoxicosis using a sensitive TSH radioimmunoassay.

A radioimmunoassay was optimized to measure serum TSH with maximum sensitivity (sTSH). With this assay sTSH was less than 0.5 mIU/l in 100% of 64 patients with proven thyrotoxicosis and greater than 0.5 mIU/l in 92% of 76 normal subjects. sTSH correctly predicted the TSH response to TRH (delta TSH) in 93% of 125 patients with suspected thyrotoxicosis. In this group thyrotoxicosis was excluded by an sTSH greater than 0.5 mIU/l in 52% of patients thus avoiding the need for further testing.

Humans↗
PubMed1985

Objective assessment of treatment response in hirsutism.

A simple photographic technique was used to assess the objective response of hirsute women to treatment with cyproterone acetate (CA). The skin in front of the left ear was shaved and photographs taken immediately and after 1 week, and hair growth per week estimated by averaging the length of 20 hairs in the magnified photographs. The precision, repeatability and patient acceptance of the method were found to be satisfactory. Basal hair growth rates were 2.28 +/- 0.4 mm/week (mean +/- SD, n = 34) and showed a significant correlation with hirsutism scores derived from a standard physician-rated scale. During therapy with CA the mean (+/- SD) improvement in hair growth rate was 19 +/- 13%, whereas physician-rated hirsutism scores improved by 33 +/- 20%. The reduction in hair growth rate showed no significant correlation with improvement assessed using subjective rating by either physician or patient. The greater improvement in physician-rated scores compared with hair growth rate assessment suggests that hair shaft width, colour and other factors may be as important as hair length when assessing treatment response.

Adolescent↗
PubMed1985

Cyproterone acetate as initial treatment and maintenance therapy for hirsutism.

Thirty-four patients with hirsutism were treated for 9 months with 100 mg cyproterone acetate (CA) given on days 5-15 of the menstrual cycle together with a combination oral contraceptive containing 2 mg CA and 50 micrograms ethinyloestradiol (Diane) given on days 5-25 of the cycle. After 9 months treatment patients were randomised to a 12 month double-blind cross-over trial comparing Diane plus 25 mg CA with Diane plus placebo, to test the efficacy of low-dose CA as maintenance therapy. Thirty-one patients (92%) experienced moderate or good subjective improvement in hirsutism on high-dose CA, associated with a 40% mean overall improvement in objective hirsutism grade and 13% overall reduction in hair growth rate measured by a photographic technique. Minor or moderate side effects were experienced by 64% of patients and severe side effects by 11% at this dosage. There was a mean subjective relapse rate of 33% when patients were changed to low dose CA, and relapse rates were not significantly different between the two regimens with 28% relapsing on 25 mg CA + Diane and 48% on placebo and Diane (P less than 0.05). Despite significant subjective relapse with low-dose treatment there was no significant deterioration in objective hirsutism grade or hair growth rate determined photographically. Levels of plasma testosterone, sex hormone binding globulin, free testosterone (derived) and androstenedione fell significantly on high dose CA and this reduction was maintained during low dose therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Goitre and thyroid dysfunction during chronic amiodarone treatment.

We measured thyroid function in a cross-sectional survey of 37 unselected patients receiving chronic amiodarone treatment. Palpable goitre was presented in 17 patients and was a new finding in ten. Despite frequent elevations of serum free T4 (67%) or free T4 index (43%), all 37 patients were clinically euthyroid with a normal or decreased serum free T3 or free T3 index. Mean urine iodide/creatinine excretion was increased 13-fold. Three patterns of thyroid function were seen; in 21 patients with normal TRH responses, the mean basal serum TSH was significantly elevated. Five patients had biochemical hypothyroidism which did not require treatment. Eleven patients had evidence of thyroid autonomy and the three patients with absent TRH responses each gave a past history of goitre or thyrotoxicosis; a trial of carbimazole treatment in these three was without clinical benefit. The observed spectrum of subclinical goitre and thyroid dysfunction may result from an unpredictable thyroid response to excessive free iodide combined with a weak goitrogenic effect of amiodarone mediated by increased TSH secretion.

Adult↗
PubMed1984

Iodine intake in an urban environment: a study of urine iodide excretion in Auckland.

Dietary iodine intake was estimated by measurement of iodide in random overnight 12 hr and 24 hr urine samples. Urinary iodide excretion was measured in 231 healthy females comprising 127 female secondary students (ages 16-19), 27 female tertiary students (17-23 yr), 42 female laundry workers (18-52 yr) and 26 pregnant women in the third trimester (18-40 yr). Urine iodide excretion was also examined in a group of 28 patients attending a thyroid clinic, with thyroid disease of diverse aetiology and in 34 patients taking the antiarrhythmic drug amiodarone for control of cardiac arrhythmias. The mean daily urine iodide excretion was 2.4 mumol/day (0.9-5.8 mumol/day) and iodide to creatinine ratio 0.21 mumol/mmol (0.09-0.29). Iodine deficiency (less than 0.4 mumol/day) was not observed in any subject. Excessive iodine (greater than 8 mumol/day) was found only in patients known to be taking iodine-containing drugs and in one normal individual. The urine iodide was normal in 154 female students, 14 of whom had a trivial thyroid enlargement. The study suggests that dietary sources other than iodised salt contribute significantly to dietary iodine intake and that residual goitre in the community is not secondary to deficiency or excess of dietary iodine.

Adolescent↗
PubMed1984

Clinical and biochemical evaluation of patients with hirsutism.

Patients with moderate to severe hirsutism presenting over an 18-month period to an endocrine clinic were assessed by clinical evaluation and hormone measurements. Hair growth rate was estimated by a photographic technique and the severity of hirsutism graded using an objective scale. Of 43 patients, 9 had polycystic ovaries and the remainder were considered to have idiopathic hirsutism. The most severely affected group had significantly increased hair growth rates compared with less clinically affected subjects, and 47% of this group showed objective features of virilization. However, apart from a significantly higher 24-hr urine 17-ketosteroid excretion all other hormonal patterns were not significantly different between severely and mildly affected patients. Serum levels of testosterone (T), sex hormone-binding globulin (SHBG), free T (calculated from T and SHBG values), and androstenedione (A) were abnormal in 44%, 51%, 60% and 60% of patients respectively, whereas plasma levels of the specific adrenal androgen DHAS were increased in 40% of patients. There was an overlap between patients with elevated hormone levels, although isolated elevation of T, A or DHAS were seen in 9%, 19% and 3% of patients respectively. In 19% of patients all serum androgen measurements were normal. Gonadotrophin levels were significantly lower in the more severely affected group. Thus androgen levels in patients with idiopathic hirsutism or polycystic ovaries, show considerable overlap with measurements in normal subjects, and elevated plasma androgens may be of adrenal (DHAS) or combined adrenal/ovarian (T, A) origin.

17-Ketosteroids↗
PubMed1983

Effect of cyproterone acetate on glucocorticoid secretion in patients treated for hirsutism.

The effect of cyproterone acetate (CA) on adrenal glucocorticoid secretion was studied in 35 women with hirsutism. Patients were treated for 9 months with 100 mg CA orally 10 days each month, administered in reverse sequence with 21 days of a combination oral contraceptive containing 50 micrograms ethinyloestradiol and 2 mg CA. During treatment one patient had a mildly impaired plasma cortisol response to insulin-induced hypoglycaemia and 2 patients showed slight reduction of the plasma cortisol response to ACTH. Responses to metyrapone were normal in all patients tested. Overall, the mean response to these tests was significantly greater during CA treatment compared with pre-treatment measurements, probably due to effects of oestrogen on cortisol-binding globulin. In all patients urinary cortisol excretion remained normal and no patient demonstrated any features of steroid insufficiency. Thus it appears that CA has no untoward effect upon glucocorticoid secretion when given in high dosage for prolonged periods to hirsute women.

17-Hydroxycorticosteroids↗