Data extraction

In total, 1037 records were identified: 191 results were obtained via Medline, 453 from the EMBASE database, 193 from the Web of Science database and 200 from the Google Scholar database, which then underwent screening (Fig. 1 in the Supplement). Finally, 42 papers were included in this review [3, 10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51].

Patients’ characteristics

A total of 234 patients from 42 papers were included in this review. The patients had a pooled mean age of 42.8 ± 11.4 years and were predominantly females (n = 144, 61.5%).

The most frequent etiology of thyrotoxicosis was Graves’ disease, which represented over two thirds of the reported cases (n = 163, 69.7%). A complete list concerning the etiology in the full cohort of included series/reports is provided in Table 2.

Table 2 Patient data and averages (n = 234)Plasmapheresis: indications

The dominant indications for TPE were side effects due to conventional treatment (n = 91, 39.1%), such as hepatotoxicity (n = 36, 15.4%), agranulocytosis (n = 26, 11.1%), allergic reactions (n = 4, 1.7%), thrombocytopenia (n = 1, 0.4%), unspecified (n = 24, 10.3%). The other indications are summarized in Table 3.

Table 3 Indications for TPEThe choice of method and replacement fluid

Centrifugal therapeutic plasma exchange (cTPE) was used in 185 patients (93.4%) and membrane therapeutic plasma exchange (mTPE) in 13 patients (6.6%). In 11 patients, both the cTPE and mTPE were used during treatment [25]. 25 patients could not be assigned to either method due to lack of data [3, 16, 17, 20, 25, 26, 29, 35, 37, 39,40,41,42,43,44,45, 47, 50, 51].

Fresh frozen plasma (FFP) was used in 101 patients (43.2%), an albumin solution in 46 (19.7%), a combination of both FFP and albumin in 47 (20.0%), and hydroxyethyl starch in 3 patients (1.3%). In 37 instances (15.8%), no information was provided about the selected replacement fluid. We found no differences in the effectiveness of TPE in lowering thyroid hormone levels according to the fluid used.

Volume and frequency

The volume used during plasmapheresis was calculated as 1–1.5 × of patient’s plasma estimated volume in 7 studies [8, 10, 12, 16, 19, 28, 42]. In the remaining cases containing this information, the plasma volume ranged from 1.5 to 4 L [11, 17, 22, 25, 30,31,32, 34, 36, 47]. A total of 83 patients underwent TPE sessions every 24–48 h [12, 16, 19, 21, 22, 27, 32, 39, 41, 44]. TPE sessions performed within a shorter time window (every 7–19 h) were described in 2 case reports [11, 17].

Flow rate and duration of session

In the majority of the series/reports, the flow rate ranged from 50 to 80 ml/min [8, 16, 19, 22, 44]. One trial used a higher flow rate of 200 ml/min [30]. When specified, the duration of a TPE cycle ranged from 2 to 5 h [8, 16, 19, 29, 32, 33, 47].

The time between the last plasmapheresis session and surgery

Surgical intervention was performed within 24 h after the last TPE session in 31 patients. Significant perioperative bleeding was reported in 6 patients [10, 15, 17,18,19, 22, 24, 28, 34, 36, 38, 42,