Plasma interleukin-6 and C-reactive protein levels in reactive versus clonal thrombocytosis

Am J Med. 1994 Oct;97(4):374-8. doi: 10.1016/0002-9343(94)90306-9.

Abstract

Purpose: Evaluate the discriminatory value of plasma interleukin-6 or C-reactive protein levels in clonal thrombocytosis compared with those in reactive thrombocytosis.

Patients and methods: A comparative analysis of quantitatively measured laboratory values in a prospectively studied group of consecutive patients. The setting was a tertiary referral center consisting of two hospitals and an outpatient clinic. Plasma interleukin-6 and C-reactive protein levels were measured in 91 consecutive patients with thrombocytosis (platelet count > or = 600 x 10(9)/L). The cause of thrombocytosis was determined by reviewing the medical histories and follow-up data without knowledge of the corresponding laboratory values. Sixty-four patients had reactive thrombocytosis, 20 had clonal thrombocytosis, and 7 had clonal thrombocytosis plus reactive thrombocytosis. Plasma interleukin-6 was measured by an enzyme-linked immunosorbent assay, and C-reactive protein was measured with rate immunonephelometry.

Results: Interleukin-6 levels were undetectable in all the patients with clonal thrombocytosis, whereas they were increased in 60% of the patients with reactive thrombocytosis or clonal thrombocytosis plus reactive thrombocytosis. There was a correlation between interleukin-6 and C-reactive protein levels (r = .6), and the median and range values of both levels differed significantly between the clonal thrombocytosis group and the other two groups (P < 0.0001). In 81% of the patients with reactive thrombocytosis, levels of either interleukin-6 or C-reactive protein were elevated. There was no correlation between interleukin-6 and C-reactive protein levels and the platelet count.

Conclusions: An elevated interleukin-6 level is rare in uncomplicated clonal thrombocytosis and suggests reactive thrombocytosis. However, an isolated normal value has little discriminatory value. Measurement of C-reactive protein level may be used as a less expensive surrogate for measurement of interleukin-6. Repeatedly low levels of both interleukin-6 and C-reactive protein are most consistent with clonal thrombocytosis.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • C-Reactive Protein / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunoassay
  • Interleukin-6 / blood*
  • Male
  • Middle Aged
  • Nephelometry and Turbidimetry
  • Platelet Count
  • Prospective Studies
  • Thrombocytosis / blood*
  • Thrombocytosis / etiology
  • Thrombocytosis / immunology

Substances

  • Interleukin-6
  • C-Reactive Protein