Iron deficiency, an unusual cause of thrombocytopenia: results from a multicenter retrospective case-controlled study

Iron deficiency anemia (IDA) is often associated with mild to moderate thrombocytosis, and iron deficiency-associated thrombocytopenia (IDAT) is much more uncommon and often misdiagnosed as immune thrombocytopenia (ITP). To better describe the features of IDAT, we conducted a retrospective multicenter case-control study. We identified 10 patients (9 women) with a definite diagnosis IDAT, with a median age of 43.5 [range, 16-72] years and a median platelet count of 30.5 × 10⁹/L [range, 21-80], and 7 patients with a possible diagnosis of IDAT. Bleeding manifestations were absent in all patients but one. All the patients recovered (platelet count ≥ 150 × 10⁹/L) upon iron therapy ± red blood cell transfusion after a median time of 6 [4-39] days. When compared with 30 randomly newly diagnosed ITP patients matched on age, the baseline platelet count was significantly lower in ITP (median = 7 × 10⁹/L [4-59], p < 0.001) whereas MPV was higher (10.5 fL [9,4-13,8] vs 8.2 fL, for IDAT p < 0.001). The median platelet count on day 7 was 337 × 10⁹/L [113-1000] for IDAT cases vs 72 × 10⁹/L [13-212] for ITP controls (p < 0.001). IDAT is potentially an under-recognized cause of thrombocytopenia that may be easily managed with iron therapy.