Ferritin

A case-control study was conducted at Saad Abuelela Maternity Hospital in Khartoum, Sudan, from June to December 2020. The cases were 60 pregnant women who presented with preeclampsia and have no history of pre-existing hypertension. Preeclampsia was defined as per the American College of Obstetricians and Gynaecologists criteria (ACOG Committee on Practice Bulletins—Obstetrics, 2020 (link)): pregnant women with onset of new hypertension (an average blood pressure reading of ≥140/90 mmHg taken on two occasions at least six hours apart) with proteinuria (≥ 300 mg/24 h) or features of end organ dysfunction in a previously normotensive woman. Preeclampsia was classified as severe in women with an average blood pressure reading of  ≥ 160/110 mmHg on two occasions or HELLP syndrome, which includes haemolysis, elevated liver enzymes and low platelet count; otherwise, preeclampsia was considered mild (ACOG Committee on Practice Bulletins—Obstetrics, 2020 (link)). The condition was also categorised as early presentation or late-onset preeclampsia, before and after 34  weeks, respectively (Tranquilli et al., 2013 (link)). Sixty healthy pregnant women without any systemic disease, such as hypertension, diabetes mellitus, renal disease or thyroid disease, served as a control for each preeclampsia case. Women with multiple pregnancies, diabetic women, smokers and women with fetuses who had major anomalies or died were excluded from both groups in the study.
After signing informed consent, the women were asked about their sociodemographic, obstetrics and clinical data, including age, parity, educational level, residence of antenatal attendance and history of miscarriage and preeclampsia/hypertension. Body mass index (BMI) was computed from the measured weight and height.
Then, 5 mL of blood was collected from each subject at the diagnosis and separated into two equal aliquots for blood and serum analysis. Haemoglobin levels were measured using a modern haematology analyser (Sysmex KX21n, Japan) according to the manufacturer’s instructions. The blood was then centrifuged and stored at −20°C until the assay of these elements. Serum ferritin was determined using the ferritin chemiluminescent immunoassay sandwich method [TOSOH instrument (AIA360), Japan]. Serum iron and total iron-binding capacity (TIBC) were measured using a colorimetric assay (Roche Diagnostics, Germany Cobas 311). Serum hepcidin and IL-6 concentrations were measured using an enzyme-linked immunosorbent assay according to the manufacturer’s instructions (Euroimmun, Lubeck, Germany).
The sample included 60 women in each group (ratio of 1:1) and was calculated using mean difference of 5 in the iron levels between the women who had preeclampsia and the healthy controls as reported before (Duvan et al., 2015 (link)). The sample size was used to achieve 80% power and a precision of 5%. It was assumed that 10% of the women would not respond or would provide incomplete data.