Reference values for 34 frequently used laboratory tests in 80-year-old men and women.
OBJECTIVE
Reference values are usually based on blood samples from healthy individuals in the age range 20-50 years. Most patients seeking health care are older than this reference population. Many reference intervals are age dependent and there is thus a need to have appropriate reference intervals also for elderly individuals.


METHODS
We analyzed a group of frequently used laboratory tests in an 80-year-old population (n=531, 266 females and 265 males). The 2.5th and 97.5th percentiles for these markers were calculated according to the International Federation of Clinical Chemistry guidelines on the statistical treatment of reference values.


RESULTS
Reference values are reported for serum alanine transaminase (ALT), albumin, alkaline phosphatase, pancreatic amylase, apolipoprotein A1, apolipoprotein B, apolipoprotein B/apolipoprotein A1 ratio, aspartate aminotransferase (AST), AST/ALT ratio, bilirubin, calcium, calprotectin, cholesterol, HDL-cholesterol, creatinine kinase (CK), creatinine, creatinine estimated GFR, C-reactive protein, cystatin C, cystatin C estimated GFR, gamma-glutamyltransferase (GGT), iron, iron saturation, lactate dehydrogenase (LDH), magnesium, phosphate, transferrin, triglycerides, urate, urea, zinc, hemoglobin, platelet count and white blood cell count. The upper reference limit for creatinine and urea was significantly increased while the lower limit for iron and albumin was decreased in this elderly population in comparison with the population in the Nordic Reference Interval Project (NORIP).


CONCLUSIONS
Reference values calculated from the whole population and a subpopulation without cardiovascular disease showed strong concordance. Several of the reference interval limits were outside the 90% confidence interval of NORIP.
Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Johanna
J
Helmersson-Karlqvist
Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Peter
P
Ridefelt
Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
Lars
L
Lind
Department of Medical Sciences, Uppsala University, Uppsala, Sweden. Electronic address: anders.larsson@akademiska.se.
Anders
A
Larsson
D000369:Aged, 80 and over; D001053:Apolipoproteins / Q000097:blood*; D001663:Bilirubin / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D002118:Calcium / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood; D004798:Enzymes / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000097:blood; D007958:Leukocyte Count; D039841:Leukocyte L1 Antigen Complex / Q000097:blood; D008274:Magnesium / Q000097:blood; D008297:Male; D010710:Phosphates / Q000097:blood; D010976:Platelet Count; D012016:Reference Values; D012709:Serum Albumin / Q000378:metabolism; D061250:Transferrins / Q000097:blood; D014280:Triglycerides / Q000097:blood; D014508:Urea / Q000097:blood; D014527:Uric Acid / Q000097:blood; D015032:Zinc / Q000097:blood
D001053:Apolipoproteins; D008076:Cholesterol, HDL; D055316:Cystatin C; D004798:Enzymes; D006454:Hemoglobins; D039841:Leukocyte L1 Antigen Complex; D010710:Phosphates; D012709:Serum Albumin; D061250:Transferrins; D014280:Triglycerides; D014527:Uric Acid; D014508:Urea; D002097:C-Reactive Protein; D003404:Creatinine; D007501:Iron; D008274:Magnesium; D015032:Zinc; D001663:Bilirubin; D002118:Calcium
Age 80 and over; Clinical laboratory techniques; Reference values