Population screening for autoimmune thyroid disease.

Whether or not healthy adults in the community would benefit from screening for autoimmune thyroid disease is controversial. Although the prevalence of unsuspected overt thyroid disease is low, a significant proportion of subjects tested will have evidence of mild thyroid failure or excess. This article assesses whether subclinical thyroid disease is of sufficient clinical importance to warrant screening and, once detected and confirmed, to justify therapy. Population screening for autoimmune thyroid disease is assessed against recently revised screening criteria, using data from epidemiologic studies. Recommendations are proposed that may be applied in any iodine-replete community.

Thyroid hormone concentrations in a large scale community survey. Effect of age, sex, illness and medication.

Total thyroid hormone concentrations have been measured in the course of a large scale community survey to determine the distribution of these variables in the normal population and to assess the effect of age, sex, previously undectected thyroid disease and medication upon these parameters. 2779 subjects were studied. Serum T4 concentrations were normally distributed. A progressive increase in T4 levels with age was noted in the males, and a smaller increase in females which was concealed by the raised T4 values secondary to oral contraceptive therapy in females under the age of 45. Serum T3 levels were also normally distributed. There was a small reduction in T3 with age in the males but this fall was not seen in the females. T3 values were relatively higher in females under the age of 45 but this increase was not noted after exclusion of subjects taking an oral contraceptive. The changes in thyroid hormone concentrations with age are relatively minor (particularly with respect to T3) in a randomly selected sample from an English town. It is suggested that the changes reported by other authors reflect the process of selection used, and the high frequency of undetected thyroid disease, other illness and medication in hospital-based communities.

The development of ischemic heart disease in relation to autoimmune thyroid disease in a 20-year follow-up study of an English community.

The original Whickham Survey documented risk factors for cardiovascular disease and the prevalence of thyroid disorders in a sample of 2779 adults that closely matched the British population. A 20-year follow-up study has determined outcomes in terms of morbidity and mortality from ischemic heart disease in over 97% of the original survey population. Analysis of deaths from all causes and from ischemic heart disease showed no association with antithyroid antibody status identified at first survey. A multiple logistic regression using the development of ischemic heart disease in the total population at follow-up as the dependent variable found that the significant predictor variables for men were age, cholesterol, mean arterial blood pressure, smoking history, and skinfold thickness index. For women only age, cholesterol, and mean arterial blood pressure were significant. The presence of autoimmune thyroid disease, as defined by either hypothyroidism, positive antithyroid antibodies, or raised serum thyrotropin at first survey, was not significant. A retrospective cohort study of a subsample of women identified at first survey with positive antithyroid antibodies or raised serum thyrotropin and closely matched controls found no significant association with mortality or development of ischemic heart disease. There is no evidence from this study to suggest that evidence of autoimmune thyroid disease identified 20 years ago is associated with an increased risk of ischemic heart disease.

Comparison of non-mydriatic retinal photography with ophthalmoscopy in 2159 patients: mobile retinal camera study.

OBJECTIVE: To determine whether non-mydriatic Polaroid retinal photography was comparable to ophthalmoscopy with mydriasis in routine clinic screening for early, treatable diabetic retinopathy. DESIGN: Prospective study of ophthalmoscopic findings according to retinal camera screening and ophthalmoscopy and outcome of referral to ophthalmologist. SETTING: Outpatient diabetic clinics of three teaching hospitals and three district general hospitals. PATIENTS: 2159 Adults selected randomly from the diabetic clinics, excluding only those registered as blind or those in wheelchairs and unable to enter the screening vehicle. MAIN OUTCOME MEASURES: Numbers of patients and eyes correctly identified by each technique as requiring referral with potentially treatable retinopathy (new vessel formation and maculopathy) and congruence in numbers of microaneurysms, haemorrhages, and exudates reported. RESULTS: Camera screening missed two cases of new vessel formation and did not identify a further 12 but indicated a need for referral. Ophthalmoscopy missed five cases of new vessel formation and indicated a need for referral in another four for other reasons. Maculopathy was reported in 147 eyes with camera screening alone and 95 eyes by ophthalmoscopy only (chi 2 = 11.2; p less than 0.001), in 66 and 29 of which respectively maculopathy was subsequently confirmed. Overall, 38 eyes received laser treatment for maculopathy after detection by camera screening compared with 17 after ophthalmoscopic detection (chi 2 = 8.0; p less than 0.01). Camera screening underestimated numbers of microaneurysms (chi 2 = 12.9; p less than 0.001) and haemorrhages (chi 2 = 7.4; p less than 0.01) and ophthalmoscopy underestimated hard exudates (chi 2 = 48.2; p less than 0.001). CONCLUSIONS: Non-mydriatic Polaroid retinal photography is at least as good as ophthalmoscopy with mydriasis in routine diabetic clinics in identifying new vessel formation and absence of retinopathy and is significantly better in detecting exudative maculopathy.

Renal replacement treatment for diabetic patients in Newcastle upon Tyne and the Northern region, 1964-88.

OBJECTIVES: To review the experience of renal replacement treatment in diabetic patients treated in Newcastle upon Tyne and the Northern region from 1964 to 1988, and to compare the morbidity and mortality of diabetic patients treated with dialysis or transplantation with those of matched controls of non-diabetic patients. DESIGN: Retrospective study of clinical case notes. SETTING: Renal units of the Northern region, particularly that in Newcastle upon Tyne. PATIENTS: All 65 diabetic patients treated by renal replacement treatment in Newcastle upon Tyne from 1964 to 1987; 42 diabetic patients were matched with 42 non-diabetic patients according to age, sex, year of starting treatment, and type of treatment (dialysis or transplantation). MAIN OUTCOME MEASURES: Sex, age, renal biopsy findings, blood pressure, history of diabetic treatment, and plasma creatinine concentration at the start of renal replacement treatment. History of renal replacement treatments, suitability for transplantation, history of transplantation, cumulative survival, and cause of death during follow up. Survival of technique, cumulative survival of the first peritoneal catheter and history of peritonitis in patients treated with continuous ambulatory peritoneal dialysis; source of graft, histocompatibility antigens, duration of associated stay in hospital, and graft survival in patients receiving renal or pancreatic transplant. RESULTS: 1259 Patients with chronic renal failure were accepted for renal replacement treatment in Newcastle upon Tyne, of whom 65 (5%) had diabetes. The first was accepted in 1974, and between 1974 and 1980 another 15 were treated (mean age 42 years; 4% of new patients). From 1981 to 1987, 49 diabetic patients (mean age 44; 9% of new patients) were treated. Fifty patients (77%) had insulin dependent diabetes and the remaining 15 (23%) non-insulin dependent diabetes. On average, the patients were aged 25 (range 5-57) when diabetes was first diagnosed and 44 (range 24-70) at the start of renal replacement treatment. The mean age at the start of treatment was 40 for patients with non-insulin dependent diabetes and 58 for patients with non-insulin dependent diabetes. Transplantation was performed in 33 of the diabetic patients, whose mean age was lower than that of those who did not receive a transplant (41 v 48 respectively, p less than 0.05). Comparison between the 42 diabetic patients and matched controls showed that the overall survival at five years was 46% and 77% respectively. The three year survival of the diabetic patients who did not receive a transplant was poor (41% v 79% respectively). Of patients transplanted, survival at five years was 73% in the diabetic patients and 90% in the controls. However, there was no significant difference in the five year graft survival (64% v 46% respectively). CONCLUSIONS: Diabetes adversely affects morbidity and mortality in patients having renal replacement treatment, but renal transplantation seems to be the best option for treating diabetic patients with end stage renal failure.

The epidemiology of hypothyroidism--an update.

Comparison of studies of the prevalence and incidence of hypothyroidism is hampered by differing definitions and population samples. Using a uniform set of diagnostic criteria, the prevalence of previously undiagnosed, spontaneous, overt hypothyroidism in community-based studies has been estimated between 2-4/1000 total population world-wide. If all cases of previously diagnosed hypothyroidism, previous thyroid surgery and radioiodine treatment are included, this prevalence rises to approximately 10/1000, and if subclinical cases are included, then the prevalence is probably over 50/1000 total population. The annual incidence of overt hypothyroidism is between 1-2/1000 for female and around 2/10,000 for males, with individuals having previously elevated TSH and positive circulating thyroid autoantibodies, being particularly at risk. The question of widespread population screening for hypothyroidism is unsettled, but it is probably not cost-effective unless incorporated as part of a screening programme for other conditions such as cervical cancer, or targeted at high risk groups such as post-menopausal women. The combination of serum TSH estimation and a high clinical index of suspicion should detect most patients with thyroid dysfunction, although detailed studies on the use of the more sensitive assays in the detection of both hyper- and hypothyroidism have yet to be published.

Information loss in limb-lead electrocardiograms compared with twelve-lead tracings in a population survey among the elderly.

A total of 235 telve-lead electrocardiogram tracings representing all those traces with positive Minnesota codings from a population sample of persons aged 65 and over were re-coded on the basis of the six limb-leads alone. The over-all loss of information amounted to about 22.3 per cent of major abnormalities, as defined, but was higher than 50 per cent for some individual abnormalities such as abnormal Q and QS waves. Possible implications of these findings are discussed.

Low incidence of chlorpropamide-alcohol flushing in diet-treated, non-insulin-dependent diabetes.

50 diet-treated, non-insulin-dependent diabetics were tested subjectively and objectively for chlorpropamide-alcohol flushing (CPAF) with a single challenge test. Of the 12 (24%) who reported a subjective flush, 9 (18%) also flushed when a placebo was given instead of chlorpropamide, so the true incidence of chlorpropamide-alcohol flushing was 4% (1 patient was not retested with placebo). In a control group of 21 non-diabetics, 2 showed the specific CPAF phenomenon. Temperature measurement did not improve discrimination, but it did show a faster rise in facial temperature in CPAF-positive subjects than in alcohol flushers. This study does not confirm previous higher estimates of the incidence of the CPAF phenomenon in non-insulin-dependent diabetes.

Age-associated change in QRS axis: intrinsic or extrinsic ageing?

Human ageing is most usefully conceptualised as an interaction between intrinsic and extrinsic processes. Comparison of age-associated trends in populations living under different environmental conditions provides a method of recognising the effects of extrinsic influences. This paper compares the age-associated trend in mean frontal plane QRS axis in the male adult population of Pukapuka with the trend observed in an age-matched sample from a British population. The Pukapukans show no rise in mean blood pressure with age and have other features placing them at low risk of coronary heart disease. Although the British population showed the shift to the left in mean QRS axis characteristic of economically advanced populations there was no change in mean QRS axis with age among the Pukapukans. The conclusion is drawn that the shift with age in QRS axis observed in advanced populations is extrinsic in origin but is not necessarily a manifestation of coronary heart disease.