Biochemical and Haematological Predictors of Reduced Neutrophil Granulocyte Count associated with Intravenous Ceftriaxone Treatment.

Background: Intravenous treatment with ceftriaxone, a commonly used third-generation cephalosporin, is associated with a risk of the potentially fatal side-effect of neutropenia. Objective: The first systematic study to determine whether six to 12 days' intravenous ceftriaxone treatment is associated with a reduction in the neutrophil count and the extent to which biochemical and/or haematological parameters routinely measured at baseline predict such a fall. Method: Baseline and follow-up haematological and biochemical blood indices were measured in 86 patients (mean age 39.4 years; 55 female) receiving 2 g intravenous ceftriaxone daily. Results: At follow-up, the mean (standard error) neutrophil count had fallen from 3.93 x 10(9) (0.16 x 10(9)) L-1 to 3.15 x 10(9) (0.15 x 10(9)) L-1 (p < 0.000001). This reduction was predictable according to the following multifactor linear regression model: (baseline neutrophil count (x 10(9) L-1)) - (follow-up neutrophil count (x 10(9) L-1)) = 76 + 159.2(baseline haematocrit) - 14.5(baseline red blood cell count (x 10(12) L-1)) - 0.724(baseline mean corpuscular volume (fL)) + 0.474(baseline neutrophil count (x 10(9) L-1)) + 0.0448(baseline total iron binding capacity (mu M)) + 7.15(baseline calcium ion concentration (mM)) - 13.2(baseline corrected calcium ion concentration (mM)) + 0.0166(baseline alkaline phosphatase (IU L-1)). The residuals were normally distributed and model testing by random partition of the original data into two parts, with training of the model using the first part and model testing with the second part, gave highly satisfactory results. Conclusion: Intravenous ceftriaxone treatment is associated with a fall in neutrophils, which can be predicted by routine baseline blood indices.