Impact of Splenectomy on Postsurgical Platelet Count
Authors: Sande Christopher , Maliske Seth , Zimmerman M Bridget , Reinke Dennis Aaron , Perepu Usha , Holman Carol 
Published: September 2019

Abstract

This study investigates both the short- and long-term effects of splenectomy on platelet count.

Methods
Patients treated at our tertiary care center in years 2012-2016 with a history of splenectomy (assessed by corresponding ICD-9 and ICD-10 codes) were included if they had platelet count data available within the first 5 years postsplenectomy. Indication for and date of splenectomy as well as all platelet counts were extracted. Patients were sorted by splenectomy indication into ITP, clonal myeloid neoplasm, nonmyeloid malignancy, and trauma/other categories. ITP patients were divided further into responders, partial responders, and nonresponders. The 180-day time course of the platelet counts was graphed for patients who had at least five platelet counts performed 1 to 180 days after splenectomy. For each group of patients, a curve of best fit was identified, from which peak platelet count, days to peak platelet count, platelet count at stable state, and days to stable state were calculated. Additionally, average platelet counts for time intervals extending from prior to splenectomy to 5 years postsplenectomy were calculated for each group, including all counts available from any patient in that group.

Results
We identified 129 patients with a history of splenectomy. Median age at splenectomy was 36 years (range, 2-94) with 59 females and 70 males. Eighty patients underwent splenectomy for trauma/other, 21 for nonmyeloid malignancy, 6 for clonal myeloid neoplasm, and 22 for ITP. Among the ITP patients, 16 experienced complete response (2 with subsequent relapse), 3 were partial responders, and 3 were nonresponders. Overall, the trauma/other group showed the greatest degree of postsplenectomy thrombocytosis, rising from a preoperative platelet count of 154 K/µL to a maximum of 807 K/µL at postoperative day 15.4. In comparison, the nonmyeloid malignancy group rose from 95 K/µL in the week presplenectomy to a maximum of 345 K/µL at day 23.7. The trauma/other group also reached stable state more quickly (day 21.4 vs 38.0) and at a higher stable platelet count (586 K/µL vs 240 K/µL) than the nonmyeloid neoplasm group. By 1 to 5 years postsplenectomy, 95% of patients in our analysis had platelet counts within the standard normal range of 150 to 450 K/µL, albeit trauma/other and ITP responder patients had platelet counts toward the upper end of the normal range. Comparing ITP responders to partial responders, both groups showed a relative increase from baseline platelet count by days 22 to 29. Both groups also reached a stable platelet count by >5 years postsplenectomy with responders averaging 263 K/µL vs partial responders at 88 K/µL.

Conclusions
Our results support the well-known phenomenon of postsplenectomy thrombocytosis and illustrate the difference in platelet count response by surgical indication. Furthermore, our results suggest that postsplenectomy patients should be considered to have a different “normal range” for platelet count than nonsplenectomized patients.