Biomedical subjects
I R Gunn
Publications and source records attributed to I R Gunn.
Screening for macroprolactinaemia.
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Testing for haemochromatosis in the diabetic clinic.
Random serum transferrin saturation (TS) was measured in 1194 patients attending a diabetic clinic. Twenty-one patients had TS > 55% and in three of these patients repeat random TS was < 55%. Seventeen patients were recalled for fasting serum TS and ferritin measurement. Ten patients had fasting TS > 55%. The diagnosis of haemochromatosis was confirmed by liver biopsy in a total of six patients, three of whom were previously unsuspected. Haemochromatosis was the possible diagnosis in a further four patients. Family studies using HLA typing confirmed haemochromatosis in four family members, three of whom were asymptomatic. We conclude that measurement of TS is a simple and effective method of finding cases of haemochromatosis in the diabetic clinic.
Serum parathyroid hormone levels and familial benign hypercalcemia.
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Emergency serum creatine kinase MB isoenzyme concentration in patients with suspected acute myocardial infarction.
We report the results of the introduction of a service which offered emergency measurement of serum creatine kinase MB isoenzyme concentration in patients admitted to hospital with suspected acute myocardial infarction and a non-diagnostic electrocardiogram. A retrospective study suggested that in such patients, a single admission measurement would have a diagnostic sensitivity of 70% and specificity of 100%. A prospective study employed a protocol which included repeat measurement after two hours where the initial measurement was low in samples taken less than six hours after the onset of symptoms. The prospective study showed that the service was welcomed by physicians, who employed the measurements appropriately as a supplement to, rather than substitute for, clinical judgement. In a continuing audit, 228 patients had an emergency measurement according to the agreed protocol. 79 of these had a discharge diagnosis of acute myocardial infarction. The diagnostic sensitivity and specificity of our emergency strategy were both 94%. The strategy led to the treatment with thrombolytic drugs of 73 patients who would not otherwise have been treated, 69 with a discharge diagnosis of acute myocardial infarction, and four with some other discharge diagnosis. The median time taken from requesting the analysis to reporting the result was 34 minutes. The costs and potential benefits of our strategy are discussed.
Urine calcium and serum ionized calcium, total calcium and parathyroid hormone concentrations in the diagnosis of primary hyperparathyroidism and familial benign hypercalcaemia.
A relationship between serum concentrations of ionized calcium and parathyroid hormone (PTH) in persons without parathyroid overactivity was defined by performing an oral calcium load test. As a result, a serum PTH concentration greater than 2.6 pmol/L in a hypercalcaemic patient was regarded as suggestive of hyperparathyroidism. Fasting serum PTH concentrations in 58 patients with surgically and histologically proven primary hyperparathyroidism (PHPT) were all above 2.7 pmol/L (range 3.2-84.5). Thirteen of 20 patients with familial benign hypercalcaemia (FBH) had fasting serum PTH concentrations greater than 2.6 pmol/L (range 1.6-6.1). There was a significant correlation between serum PTH and age in the FBH patients only. Fasting urine calcium excretion (CaE) ranged from 14 to 222 mumol/L of glomerular filtrate in PHPT and 3-34 mumol/L of glomerular filtrate in FBH. The best biochemical discriminant between patients with PHPT and FBH was a plot of fasting serum PTH against CaE. A plot of post-calcium load PTH against post-load CaE showed no further significant advantage in discriminating between the two conditions.
Post-traumatic hypothalamic-pituitary dysfunction presenting with biochemical features of primary hypothyroidism.
Two cases of post-traumatic hypothalamic-pituitary dysfunction are described where the primary pathology was shown to be understimulation of the pituitary by hypothalamic hormones. In each case, the biochemical presentation was a low serum thyroxine and elevated TSH concentration mimicking primary hypothyroidism. Treatment with thyroxine before cortisol replacement was not beneficial. In both cases, hydrocortisone therapy alone resulted in a rise in serum thyroxine and fall in serum TSH. Chronic cortisol deficiency may directly impair the thyroid response to TSH, whilst thyroxine appears to exert its feedback primarily at pituitary rather than hypothalamic level.
Rapid and accurate diagnosis of acute hyperparathyroid crisis.
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Biological variation of serum and urine creatinine and creatinine clearance.
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Plasma ultrafiltrable magnesium in insulin dependent diabetics.
Plasma ultrafiltrable (MgUF) and total magnesium concentrations were measured in 60 insulin dependent diabetics and compared with values in an age matched control group. Although the diabetic patients had lower plasma albumin concentrations (p less than 0.05), both ultrafiltrable and total magnesium concentrations were significantly decreased by 6.8% and 7.6%, respectively, compared with those of the controls (p less than 0.001). In the diabetic group MgUF varied inversely with fasting plasma glucose (r = -0.269, p less than 0.05). In 14 patients with significant hypomagnesaemia, fasting plasma glucose concentration was higher (p less than 0.01) and the diabetes was of shorter duration (p less than 0.05) than in 46 patients with an MgUF in the control range. The fasting urinary magnesium creatinine ratio was greater in the diabetic patients (p less than 0.05). Patients with retinopathy did not have lower plasma magnesium values than those without retinopathy.
Predictive value of CK-MB measurement in myocardial infarction.
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Prospective evaluation of urinary amylase test strip.
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Tests for growth hormone deficiency.
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High plasma osmolality following intravenous dimethylsulphoxide in the treatment of postoperative hemiplegia.
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Effects of workload and analysis time on the cost of out-of-hours investigations.
In the UK, under present Whitley Council Regulations for payment for out-of-hours pathology services, there is a complex relationship between the number of requests received, the time taken to analyse each request, and the number of calls for which payment may be claimed for work done. At a fixed average analysis time, the rate of increase of remuneration slows down as workload increases until at higher workloads remuneration falls. The introduction of methods with a shorter average analysis time to improve the clinical service increases remuneration disproportionately. We suggest that a fixed sessional payment would be a better way of funding the service.
A comparison of alternative arrangements for an out-of-hours chemical pathology service.
Until 1979, the out-of-hours chemical pathology service was the conventional on-call service in which the medical laboratory scientific officers (MLSOs) carried out analyses at the direct request of clinical staff. In 1980, during an industrial dispute, junior ward doctors were trained to use three simple instruments which are maintained by the chemical pathology department. In January, 1981, when the dispute was settled, the doctors continued to use these instruments. Analyses they could not make were done by the MLSO on call, but only after the requests were monitored by a chemical pathologist or biochemist. The result was an 80% reduction in the number of calls. When the monitoring was withdrawn in 1983, there was some increase in the number of MLSO calls, but this was still 35% less than that with the conventional system despite a 4-fold increase in the total number of analyses done out of hours between 1979 and 1984. Surveys in 1984 and in early 1985 revealed that most doctors preferred using the instruments to asking an MLSO to make the analysis.
Correlation between serum ionised calcium and serum albumin concentrations in two hospital populations.
One quarter of 172 patients from two hospitals with no obvious disturbances of calcium homeostasis and with total serum calcium concentrations that were normal after adjustment for albumin concentration had low serum ionised calcium concentrations. The low values were not due to changes in pH but were associated with hypoalbuminaemia. Significant positive regressions of ionised calcium on albumin concentration were observed in patients from both hospitals and also in 48 healthy laboratory staff. Because the regressions did not differ between patients and healthy subjects the low ionised calcium values associated with hypoalbuminaemia are unlikely to have been of pathological importance. These findings indicate that interpreting serum ionised calcium concentrations in patients with a reduced serum albumin concentration on the basis of a reference range determined in subjects with a normal serum albumin concentration may be clinically misleading.