Sickle cell disease (SCD) is an inherited autosomal recessive haemoglobinopathy characterized by chronic haemolytic anaemia.1,2 SCD consists of the haemoglobin SS (HbSS) and haemoglobin variant syndromes such as haemoglobin SC (HbSC), haemoglobin SE (HbSE).3 Sickle cell anaemia (SCA), also known as HbSS, is the most common and most severe form of SCD.4 The prevalence of sickle cell disease ranges between 10–45% in various parts of sub-Saharan Africa.5,6 Globally, over 300,000 children are born annually with SCD and about 70% of the births occur in sub-Saharan Africa.7
In Nigeria, it is estimated that 24% of the population have sickle cell trait,7 making it the country with the largest population of individuals with sickle cell trait worldwide.7 According to Mulumba et al, about 150,000 Nigerian children are born with sickle cell disease annually,5 in contrast to 250 new SCD births per annum in the United kingdom (UK) and 2000 in the United states (US).6,8 Globally, the life expectancy of women with sickle cell anaemia has improved over the last four decades due to multiple medical advancements in care.6 The survival estimates have continued to improve from a median survival of 42–48 years in 1994, to 58 years in 2014.10 It is therefore, not unusual nowadays to have patients with SCA who are 60–70 years old.11
The implication of people with SCA living longer is that they are inclined to develop complications of the disease. Endocrine complications such as thyroid and gonadal dysfunction may lead to gonadal failure/insufficiency in males and females with undesirable effects on their reproductive health.2,5 Gonadal dysfunction inherent to SCA has been described in adults (especially in males), such as hypogonadism, sperm abnormalities, and erectile dysfunction (ED).12 Although the available literature is inconclusive about gonadal failure in females with SCA,11,12 some reproductive issues that have been reported in females with SCA include delayed puberty12 and premature menopause.12 Possible explanations
for endocrine dysfunction in patients with SCA include: increased iron storage secondary to frequent blood transfusions, ischemia due to vaso-occlusive crisis and inflammatory mediators during ischemia.8,9 Assessment of ovarian reserve or function is an indicator of the reproductive potential of women. There are various markers available for assessing the ovarian reserve which include: anti-Mullerian hormone (AMH), basal follicle stimulating hormone (FSH) levels, basal oestradiol (E2), and antral follicle count.14,15 However, serum AMH is considered a novel marker for the assessment of ovarian reserve.2 AMH is a gonad specific member of the transforming growth factor beta (TGF-β) superfamily with a total weight of 140KDa.16,17 It is a dimeric glycoprotein produced by the granulosa cells in the ovary and is usually only seen at the preantral and small antral follicle stages.18 Serum AMH level is usually determined by the number of basal antral follicles,18 and does not exhibit intracycle variability, therefore it can be measured on any day of the menstrual cycle, unlike other biochemical markers such as serum basal FSH and estradiol.18,19
Despite the burden of SCD in Nigeria, there is little or no data on the impact of SCA on the ovarian reserve of reproductive-aged women in Nigeria. The aim of this study was to determine and compare the ovarian reserve in Nigerian women with and without SCA using serum AMH as a marker.