title: Age- and sex-related variations in platelet count in Italy: a proposal of reference ranges based on 40987 subjects' data.
abstract: OBJECTIVE
  Although several studies demonstrated that platelet count is higher in women, decreases with age, and is influenced by genetic background, most clinical laboratories still use the reference interval 150-400×10(9) platelets/L for all subjects. The present study was to identify age- and sex-specific reference intervals for platelet count.
  
  
  METHODS
  We analysed electronic records of subjects enrolled in three population-based studies that investigated inhabitants of seven Italian areas including six geographic isolates. After exclusion of patients with malignancies, liver diseases, or inherited thrombocytopenias, which could affect platelet count, reference intervals were estimated from 40,987 subjects with the non parametric method computing the 2.5° and 97.5° percentiles.
  
  
  RESULTS
  Platelet count was similar in men and women until the age of 14, but subsequently women had steadily more platelets than men. The number of platelets decreases quickly in childhood, stabilizes in adulthood, and further decreases in oldness. The final result of this phenomenon is that platelet count in old age was reduced by 35% in men and by 25% in women compared with early infancy. Based on these findings, we estimated reference intervals for platelet count ×10(9)/L in children (176-452), adult men (141-362), adult women (156-405), old men (122-350) and, old women (140-379). Moreover, we calculated an "extended" reference interval that takes into account the differences in platelet count observed in different geographic areas.
  
  
  CONCLUSIONS
  The age-, sex-, and origin-related variability of platelet count is very wide, and the patient-adapted reference intervals we propose change the thresholds for diagnosing both thrombocytopenia and thrombocytosis in Italy.
authors: Institute of Molecular Genetics, National Research Council of Italy, Pavia, Italy. biino@igm.cnr.it
authors: Ginevra
authors: G
authors: Biino
authors: Iolanda
authors: I
authors: Santimone
authors: Cosetta
authors: C
authors: Minelli
authors: Rossella
authors: R
authors: Sorice
authors: Bruno
authors: B
authors: Frongia
authors: Michela
authors: M
authors: Traglia
authors: Sheila
authors: S
authors: Ulivi
authors: Augusto
authors: A
authors: Di Castelnuovo
authors: Martin
authors: M
authors: Gögele
authors: Teresa
authors: T
authors: Nutile
authors: Marcella
authors: M
authors: Francavilla
authors: Cinzia
authors: C
authors: Sala
authors: Nicola
authors: N
authors: Pirastu
authors: Chiara
authors: C
authors: Cerletti
authors: Licia
authors: L
authors: Iacoviello
authors: Paolo
authors: P
authors: Gasparini
authors: Daniela
authors: D
authors: Toniolo
authors: Marina
authors: M
authors: Ciullo
authors: Peter
authors: P
authors: Pramstaller
authors: Mario
authors: M
authors: Pirastu
authors: Giovanni
authors: G
authors: de Gaetano
authors: Carlo L
authors: CL
authors: Balduini
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000166:cytology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007558:Italy; D008297:Male; D008875:Middle Aged; D010976:Platelet Count / Q000379:methods / Q000592:standards; D012016:Reference Values; D012737:Sex Factors; D013921:Thrombocytopenia / Q000097:blood / Q000175:diagnosis*; D013922:Thrombocytosis / Q000097:blood / Q000175:diagnosis*; D044465:White People
references: Thromb Haemost. 2000 Mar;83(3):480-4
references: 10744157
references: Clin Diagn Lab Immunol. 2003 May;10(3):443-5
references: 12738646
references: Nat Genet. 2009 Nov;41(11):1182-90
references: 19820697
references: Haematologica. 1999 Jun;84(6):541-7
references: 10366799
references: Haematologica. 2011 Aug;96(8):1180-8
references: 21546503
references: Hum Hered. 2007;64(2):123-35
references: 17476112
references: PLoS Med. 2006 Mar;3(3):e24
references: 16401142
references: Ann Epidemiol. 2006 Feb;16(2):123-30
references: 16246584
references: Obesity (Silver Spring). 2008 Oct;16(10):2289-95
references: 18719631
references: J Natl Med Assoc. 2006 Mar;98(3):398-402
references: 16573304
references: Am J Clin Pathol. 2002 Aug;118(2):235-41
references: 12162684
references: PLoS One. 2009;4(2):e4654
references: 19247500
references: Genes Dev. 2003 Dec 1;17(23):2864-9
references: 14665668
references: Clin Chem. 1971 Apr;17(4):275-84
references: 5552364
references: Br J Haematol. 1981 May;48(1):31-7
references: 7248189
references: Eur J Hum Genet. 2009 Dec;17(12):1635-41
references: 19550436
references: Br J Haematol. 2012 May;157(3):384-7
references: 22171955
references: J Clin Pathol. 1996 Aug;49(8):664-6
references: 8881919
references: Lab Hematol. 2004;10(1):42-53
references: 15070217
references: Haematologica. 2011 Jan;96(1):96-101
references: 20823129
references: Int J Lab Hematol. 2007 Jun;29(3):195-9
references: 17474897
references: PLoS Genet. 2012;8(3):e1002491
references: 22423221
references: Nature. 2011 Nov 30;480(7376):201-8
references: 22139419
references: Clin Diagn Lab Immunol. 1999 May;6(3):410-4
references: 10225845
references: Thromb Haemost. 2004 Feb;91(2):367-72
references: 14961166
references: PLoS One. 2009 Oct 22;4(10):e7554
references: 19847309
references: BMC Med Genet. 2007 Jun 05;8:29
references: 17550581
references: Br J Haematol. 1999 Sep;106(4):884-8
references: 10519988
references: J Med Genet. 2011 Jun;48(6):369-74
references: 21493956
references: J Clin Pathol. 1952 Feb;5(1):10-5
references: 14917765
references: Am J Clin Pathol. 1987 Mar;87(3):365-9
references: 3826001
references: Br J Haematol. 1977 Oct;37(2):295-300
references: 603762
references: Clin Chem Lab Med. 2004;42(7):710-4
references: 15327004