METHODS: Tests for LA include dilute Russell's viper venom time (dRVVT) and Kaolin clotting time (KCT). Patients with LA ratio (dRVVT screen ratio/dRVVT confirm ratio) of ≥1.2 were considered as LA positive irrespective of KCT results. KCT was considered positive if there was a prolongation in KCT screening test which was not corrected on mixing with normal plasma.
RESULTS: Of 577 patients' results, 295 were normal, 178 were KCT positive with negative dRVVT and 104 were LA positive. Incidences of thrombosis, connective tissue disease (CTD) and bad obstetric events were noted in 13%, 16% and 44% of normal patients, 9%, 22% and 49% of KCT+ patients and 23%, 37% and 17% of LA+ patients respectively. On further evaluation of dRVVT screen ratios, 431 had a ratio of <1.1, 59 had a ratio between 1.1 and 1.2 and 87 had a ratio of >1.2. Positive LA results were found in 3%, 29% and 87% of patients with dRVVT screen ratios of <1.1, 1.1 - 1.2 and >1.2 respectively.
CONCLUSION: LA+ patients had higher incidences of thrombosis and CTD as compared to normal and KCT only positive patients. There was no significant difference in clinical characteristics between normal and KCT+ patients which suggests the presence of a high rate of false-positive KCT results. Since confirmatory testing for KCT is not widely used, the option of using another LA screening test method should be considered. In regard to dRVVT testing, confirmatory test should only be performed in patients with prolonged dRVVT screening result which was not corrected upon mixing with normal plasma as required by the International Society of Thrombosis and Haemostasis guidelines on LA testing. This practice will not only result in significant cost reduction but also avoid diagnostic confusion.
METHOD: Blood samples were obtained from 20 healthy blood donors, 30 RA patients who presented with anaemia and 30 patients who had pure iron deficiency anaemia (IDA). The samples were analysed for full blood count, iron, ferritin, transferrin, soluble transferrin receptor and prohepcidin.
RESULTS: The mean prohepcidin level in the control subjects was 256 microg/L. The prohepcidin level was significantly lower in IDA patients (100 microg/L; p < 0.0001) but not significantly different from that of control in RA patients (250 microg/L; p > 0.05). Higher serum soluble transferrin receptor (sTfR) levels were observed in IDA (p < 0.0001) but not in RA compared with that of control (p > 0.05). RA patients were divided into iron depleted and iron repleted subgroups based on the ferritin level. Prohepcidin in the iron depleted group was significantly lower than the iron repleted group and the control (p < 0.0001) and higher levels were observed in the iron repleted group (p < 0.01). sTfR levels in the iron depleted group were significantly higher than the control and the iron repleted patients (p < 0.001). In the iron repleted group, sTfR level was not statistically different from that of control (p > 0.05).
CONCLUSION: Serum prohepcidin is clearly reduced in uncomplicated iron deficiency anaemia. The reduced prohepcidin levels in the iron depleted RA patients suggests that there may be conflicting signals regulating hepcidin production in RA patients. In RA patients who have reduced hepcidin in the iron depleted group (ferritin <60 microg/L) where sTfR levels are increased suggests that these patients are iron deficient. Further studies with a larger cohort of patients are required to substantiate this point.