Haematological abnormalities in a 75-year-old population. Consequences for health-related reference intervals.

A representative sample (n = 486) of a 75-year-old population was studied, and probands with defined laboratory aberrations were re-investigated. Anaemia was present in 6% of the men and 3% of the women; in 17/22 anaemic subjects a cause was found. The prevalence of plasma cobalamin concentrations less than 130 pmol/l was 6%, of iron deficiency approximately 6%. Divergences in white blood cell and platelet counts were rare. The observed haematological aberrations were almost always caused by disease. Reference intervals for haematological components were calculated in the total study group and two reference sample groups after exclusions based on anamnestic and/or laboratory screening criteria or anamnestic criteria and/or verified disease. The lower reference limits for B-Hb and P-B12 in a group obtained after exclusions based on anamnestic and screening data were considered to be minimum values for healthy subjects. The WHO criteria for anaemia were applicable.