We determined the prevalence of iron overload due to homozygous haemochromatosis in an asymptomatic Australian (predominantly Caucasian) population by surveying 1968 employees of two large corporations. Subjects were screened by measurement of transferrin saturation and serum ferritin concentration and, in all subjects with elevation of both indices, percutaneous liver biopsy was performed to establish whether significant iron overload was present. The prevalence of iron overload due to haemochromatosis in this population was 0.36%. The prevalence rate was not significantly different between males and females, suggesting that this autosomal recessive disease is expressed equally in females given an adequate dietary iron supply. The positive predictive value of a transferrin saturation consistently greater than 45% together with an elevated serum ferritin concentration was 64%. It is concluded that the prevalence of significant iron overload due to homozygous haemochromatosis warranting treatment is approximately 1:300 and that transferrin saturation should be included in existing adult health screening programmes.

We measured by different techniques the ferritin concentration in serum in two large asymptomatic Australian population samples: 1367 bank employees and 601 insurance corporation employees. Ethanol intake, diet, the frequency of blood donation, smoking and exercise habits, and past medical history were documented. The median concentration of ferritin in serum varied according to age and sex, but was generally higher than in previously reported populations under age 65 years. Results for the two population samples were in close agreement. Apart from the blood donation status, the most important factors influencing the concentration of ferritin in serum were ethanol intake in men and diet in women. Heavy ethanol intake was associated with increased values, even among men without evidence of liver disease. We conclude that the reference range for ferritin concentration in serum in the Australian population should be significantly increased and should be related to age as well as sex. This study emphasizes the need to determine local reference ranges for ferritin concentrations in serum.

In an attempt to demonstrate a rapid and economical approach to deriving reference intervals, we analyzed data on plasma calcium and phosphate from a multichannel analyzer for more than 20 000 subjects and data on alkaline phosphatase from more than 10 000 subjects. Subjects were selected by the criterion, that their results for constituents other than the one of interest were within current reference intervals. Thus we have been able to include older patients who have diseases that accompany old age, but that do not affect test results. The mean concentrations of calcium and phosphate decreased with increasing age in both sexes, except for an abrupt increase for women about the time of reaching menopause. Similarly, the mean alkaline phosphatase activity increased with age in both sexes, reflecting a skewed frequency distribution. Here also, there was an abrupt increase in the modal value for women near menopause.

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