Usefulness of blood tests carried out during screening of the elderly population in one practice.

A screening programme for elderly patients in a six partner rural practice in west Wales had been found to be unhelpful. When screening became mandatory in April 1990 it was decided to make the programme more medical. The 773 patients aged 75 years or over in the practice were therefore offered a blood test as part of the mandatory screening programme. A total of 631 blood samples were taken. On checking haemoglobin concentrations, 39 patients (6.2%) were found to have levels below 11.5 g dl-1 (30 women, nine men). Forty two patients (7.1%) were found to have a blood urea concentration of more than 10.0 mmol l-1 and only three patients were found to be deficient in potassium, none of whom were receiving long term diuretic medication. Of the 16 patients (2.8%) discovered to have a lower than normal serum thyroxine concentration, 12 were not known to the practice. A raised mean corpuscular volume (greater than 100.0 fl) was found in 35 patients (5.9%) (24 women, 11 men), but only one of these was anaemic. However, among the patients with a low mean corpuscular volume (less than 80.0 fl), seven had a haemoglobin concentration of less than 11.5 g dl-1. Although this exercise has produced clinical benefit for a few patients, and has been interesting and academically stimulating, it cannot be concluded that the benefits obtained are worth the effort that has been involved.