Scand J Rheumatology 6: 237-240, 1977

PLATELET COUNT AND DISEASE ACTIVITY IN JUVENILE RHEUMATOID ARTHRITIS G. K. M. Endresen, H. M. Hsyeraal and E. K%ss

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From Oslo Sanitetsforening Rheumatism Hospital, Oslo, Norway

ABSTRACT. Blood samples from 41 children with juvenile rheumatoid arthritis (JRA) were studied. The platelet count was tested for possible relationship and correlation with a number of clinical and laboratory parameters. High platelet count was associated with active disease, presence of secondary amyloidosis, and poor functional capacity. The platelet count was positively correlated with the erythrocyte sedimentation rate, anemia, and granulocytosis. The platelet count thus seems to provide an additional parameter of disease activity in patients with JRA.

No thorough investigations on platelet counts in juvenile rheumatoid arthritis (JRA) have been reported. In adult rheumatoid arthritis (RA), an association seems to exist between high platelet counts and high disease activity (4, 9, 1 1 , 21). Elevated platelet counts have been observed in about one-third of 115 RA patients (21) and in a similar proportion of 22 patients with ankylosing spondylitis (22). About half of the patients with secondary amyloidosis had thrombocytosis. However, no special relationship between platelet count, renal function or rheumatoid factor titre has been observed (21.22, 23). High platelet counts may be observed in a number of conditions, e.g. myeloproliferative (16) and other malignant diseases (241, but, in general, the significance and the underlying mechanisms are indeterminate. The aim of the present study was to examine the platelet counts in children with JRA and to compare these counts with various parameters of disease activity .

MATERIALS AND METHODS Platelet counts from 41 patients (28 females and 13 males, aged 2-16 years) were available in a study on 44

hospitalized children with JRA (12, 13). The disease was diagnosed according to the criteria of Ansell & Bywaters (2) and classified as active in 25 patients ( I ) . The mean duration of the disease was 3.2 years (range 0.2-1 1.8 years). Polyarticular disease type was seen in 24 patients, oligoarticular in 12 and acute febrile type in 5 (6). Four patients belonged to functional capacity class I, 32 to class 11, 4 to class 111 and one to class IV (25). Two patients had chronic iridocyclitis. Rheumatoid factor was found in sera from 8 patients and granulocyte reactive antinuclear factor in sera from 22 patients. Six patients had amyloidosis verified by Congo red and immunofluorescence staining of biopsy specimens from liver and/or kidney. The patients received one or more of the following drugs: salicylates, hydroxychloroquine, gold, and azathioprine. In addition, 1 1 of the children were treated with varying dosages of prednisone. The hematologic parameters included hemoglobin concentration (Hb), erythrocyte sedimentation rate (ESR) and visual counting of the total white blood cells (WBC), granulocytes and lymphocytes. In 5 cases, no differential count had been made. The hospital records were reviewed for the platelet count. Peripheral venous blood had been collected. Vitally stained platelets had been counted in a light microscope, according to the method of Kristenson (15). One platelet count had been made in each individual. In 5 cases, no platelet count was available at the time of the other studies. In these instances, platelet counts made up to 3 weeks earlier or later were used. No surgery had been performed in connection with sampling, thus avoiding post-traumatic fluctuations in platelet count. Statistics The median values and ranges are given. Correlation studies were performed by linear regression analysis. Two-sided Wilcoxon tests for two samples were used (8).

RESULTS The platelet counts in 41 JRA patients revealed considerable individual variations. The platelet values given, multiplied by loy, give the counts per litre.

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G . K . M . Endresen et al.

Table I. Relationship between platelet count and clinical disease activitylamyloidosis in patients with juvenile rheumatoid arthritis Platelet count x 108/1

No. 41 25 16 6 35

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Total Active Inactive Amy loidosis No amyloidosis

Median

Range

Pa

288

88-937

323 271

173-937 88-779

Platelet count and disease activity in juvenile rheumatoid arthritis.

Scand J Rheumatology 6: 237-240, 1977 PLATELET COUNT AND DISEASE ACTIVITY IN JUVENILE RHEUMATOID ARTHRITIS G. K. M. Endresen, H. M. Hsyeraal and E. K...
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