Markedly Elevated Intra-articular White Cell Count Caused by Gout Alone

Abstract

Joint pain accompanied by erythema, swelling, and decreased range of motion is concerning for septic arthritis and typically warrants joint aspiration. The synovial fluid white blood cell count plays a central role in the decision-making process regarding these patients. Traditional teaching holds that a cell count greater than 50,000 white blood cells/µL is likely caused by infection and therefore warrants either operative intervention or serial aspiration. This report describes 2 patients with extremely high synovial fluid white blood cell counts in the absence of infection. Case 1 involved a 59-year-old man who presented to the emergency department with sudden onset of atraumatic left elbow pain and was found to have a white blood cell count of 168,500 white blood cells/µL on joint aspiration and innumerable monosodium urate crystals. The patient ultimately improved with treatment with oral prednisone, avoiding operative intervention. Case 2 involved a 69-year-old man who presented to the emergency department with acute onset of atraumatic left knee pain. On arthrocentesis, the patient had a cell count of 500,000 white blood cells/µL and was therefore taken to the operating room for arthroscopic irrigation and debridement. Final analysis of the synovial fluid showed monosodium urate crystals and negative culture findings. These cases illustrate the highest synovial fluid white blood cell count reported in patients with gout and highlight the potential difficulty in differentiating between acute gout and septic arthritis in the setting of markedly elevated white blood cell count.

Factors to Consider When Assessing the Diagnostic Accuracy of Synovial Leukocyte Count in Periprosthetic Joint Infection

“…Crystal-induced arthritis may present with clinical manifestations that are identical to those of a PJI [72], and high WBC counts are reported in cases of acute gout (e.g. ; up to 500,000 cells/µL) [73]. It should be noted that the presence of crystal arthritis does not rule out a concurrent PJI.…”

Septic Arthritis of the Native Ankle

“…Although we are not aware of any published laboratory values that are used as a threshold for the diagnosis of septic ankle arthritis, a synovial WBC count of .50,000 cells/mm 3 is the standard cutoff that is used for native joints throughout the body 5,31,[36][37][38][39] . Nevertheless, this value has been debated, and previous research has shown that using 50,000 cells/mm 3 as a threshold for infection has a sensitivity of only 64% 31 .…”

Current Clinical Methods for Detection of Peri-Prosthetic Joint Infection

“…Although secondary to detecting pathogen presence, measuring leukocyte levels are useful in the diagnosis of PJI. Similar to other secondary methods, however, leukocyte levels are not specific for PJI and can be increased because of other causes of inflammation such as gout [70].…”