Extreme Reactive Thrombocytosis Caused by Obstructive Nephrolithiasis and Pyelonephritis

Area of Science:

• Hematology
• Nephrology
• Internal Medicine

Background:

• Reactive thrombocytosis typically presents with platelet counts below 1000 × 10⁹/L.
• Elevated platelet counts can be associated with various underlying conditions, including infections and inflammatory processes.
• Distinguishing reactive thrombocytosis from myeloproliferative neoplasms is crucial for appropriate patient management.

Purpose of the Study:

• To report a rare case of reactive thrombocytosis exceeding 1000 × 10⁹/L.
• To highlight the association between markedly elevated platelet counts, urinary tract infections, and obstructive uropathy.
• To increase physician awareness of atypical presentations of reactive thrombocytosis.

Main Methods:

• Case report of an 80-year-old male with rheumatoid arthritis and incidental thrombocytosis.
• Diagnostic work-up including laboratory testing for infections and myeloproliferative disorders.
• Clinical management involving antibiotics and ureteral stent placement for obstructive nephrolithiasis and pyelonephritis.

Main Results:

• The patient presented with a platelet count of 1011 × 10⁹/L and subsequent leukocytosis.
• Negative results for JAK-2V617F mutation, BCR-ABL, and myeloproliferative neoplasms (MPL/CALR).
• Thrombocytosis and leukocytosis resolved with treatment for pyelonephritis and obstructive uropathy.

Conclusions:

• Reactive thrombocytosis can uncommonly exceed 1000 × 10⁹/L.
• Markedly elevated platelet counts in the context of urinary tract infections may indicate underlying obstructive uropathy.
• This case underscores the importance of considering urological causes in patients with unexplained thrombocytosis and UTI symptoms.