Laboratory results in the elderly: the Sydney Older Persons Study.

Background: The use of laboratory intervals based on younger and healthier populations is of questionable validity in older populations. The aim of this study was to examine haematological and biochemical profiles in a sample of community-dwelling older people and to study the impact of age, disease, disability and medications.

Methods: Basic haematological and biochemical values were obtained for 338 survivors of a random sample of community-living people aged 75 years or over at time of recruitment. These values were compared to the laboratory reference intervals and the effects of age, disease, medication and disability examined.

Results: The distribution of the 35 parameters measured differed from those described by the laboratory reference intervals in all but four of the variables. The values showed few significant age associations but did show associations with disease, disability and drug use.

Conclusions: Abnormalities identified in haematological and biochemical testing are not due to age but to age-related illnesses. This is contrary to previous studies reporting a change in haematological and biochemical parameters purely on the basis of age. In the presence of abnormalities, identification and clarification of disease states should be made.