Postsplenectomy Thrombocytosis and Pseudohyperkalemia in Trauma: A Case Report and Review of Literature

Abstract

P seudohyperkalemia as a cause of elevated potassium levels is an under recognized condition, which when missed can result in over treatment with potentially lethal consequences. The diagnosis has been associated classically with thrombocytosis in myeloproliferative conditions, and rarely with trauma induced splenectomy. We present a case of pseudohyperkalemia secondary to posttraumatic splenectomy thrombocytosis, in a previously healthy patient. A literature review yielded only two similar reported cases. CASE REPORTM.I., a 24-year-old Egyptian man with no known medical conditions, was involved in a pedestrian accident while walking across a street. He sustained severe head and chest injuries and was brought to our emergency department with a Glasgow Coma Scale score of 4 over 15. On examination, he was found to be unconscious, hypotensive, tachycardic, and desaturating at room air. He was immediately resuscitated with fluids, intubated and ventilated and sent for emergency computed tomography scans, which showed severe cerebral edema, contusion of left lung with a hemothorax and perisplenic collection. After insertion of a chest drain, he was sent for an exploratory laprotomy, which revealed grade IV splenic injury with a retroperitoneal hematoma in his left lumbar region. A splenectomy was performed and the patient was transferred to our intensive care unit for further management.Our patient recovered hemodynamically and his oxygen requirement decreased; but because of poor neurologic recovery, he had to undergo a tracheostomy. He was also vaccinated against both pneumococci and haemophilus influenzae. During his stay with us, he developed an intermittent fever with mild leucocytosis. A septic workup was performed but found to be negative, and the fever was determined to be central in origin. The white blood count (WBC) receded over time; however, by postoperative day 7, his blood work up showed thrombocytosis, with a platelet count of 1634 ϫ 10 9 and hyperkalemia, the serum potassium measuring 5.6 mEq/L. Electrocardiogram showed no cardiac arrhythmias, renal functions were normal, and he did not seem to have any signs of muscular weakness or respiratory insufficiency. His diet and medications were reviewed, but found to be noncontributory to hyperkalemia. We sent a simultaneous blood sample for plasma potassium, which was found to be 3.8 mEq/L. The diagnosis of pseudohyperkalemia secondary to thrombocytosis was confirmed and no potassium lowering therapy was initiated.

Spurious Electrolyte Disorders: A Diagnostic Challenge for Clinicians

“…In a retrospective series of 90 patients with thrombocytosis, pseudohyperkalemia (serum K + >5.1 mEq/l) was observed in the majority of patients (n = 54, 60%) regardless of the cause of thrombocytosis [29]. Reactive or postsplenectomy thrombocytosis is sufficient to cause artificially high potassium levels [29,30]. For example, rheumatoid arthritis, though infrequently, can induce pseudohyperkalemia possibly due to secondary thrombocytosis [31].…”

Pseudohyperkalaemia in essential thrombocytosis: an important clinical reminder

“…In leucocytosis increased cellular fragility leading to increased amounts of intracellular potassium being released into the circulation is thought to be the underlying cause. (9) Blood for the measurement of serum potassium is normally taken in bottles that contain silica and an acrylic gel polymer. The silica within these blood sample bottles promotes coagulation whereas the acrylic gel polymer stabilises the sample and enables its analysis.…”

Postsplenectomy thrombocytosis with pseudohyperkalaemia

“…Excessive platelet production occurs in myeloproliferative haematological disorders such as polycythaemia rubra vera and essential thrombocythaemia, as well as in states of inflammation (eg, chronic infections, rheumatoid arthritis). Inadequate sequestration or destruction, on the other hand, can occur in states of either functional or actual asplenia/hyposplenism 19. Persistent thrombocytosis is expected following splenectomy, particularly in the first three postoperative months 23 24.…”

“…Furthermore, pseudohyperkalaemia has been shown to occur only at platelet and leucocyte counts of more than 600×10 9 /L and 70×10 9 /L, respectively 14 18 19 27. Furthermore, the reason why pseudohyperkalaemia only occurs in certain cases of asplenia remains to be elucidated.…”