Menopause, also known as climacteric, is the phase in a woman's life when her menstrual periods stop and she is no longer able to bear children (Warren et al., 2009) [1]. Menopause occurs as a result of a decrease in the synthesis of the hormones estrogen and progesterone by the ovaries (Santoro and Randolph, 2011) [2]. For women, menopause is a significant transitional time that marks the end of their reproductive lives. The age at which a woman reaches natural menopause can be a good sign of her overall health and somatic aging, although there is a lot of variation among women (Snowdon et al., 1989) [3]. Menopause usually occurs between the ages of 45 and 55 (Deotale et al., 2015) [4].

Premenopause refers to the period of a woman's life between her first period and the onset of perimenopause symptoms (McKinlay et al., 1992) [5]. Estrogen and progesterone help to control and facilitate menstruation and conception at this time (McKinlay et al., 1992) [5]. Periods become irregular in most women, which mean they may be longer or shorter in duration, or lighter or heavier in terms of flow (Butler and Santoro, 2013) [6]. While it's common to associate menopause with an increase in renal failure, this is mostly related to advancing age and has nothing to do with menopause (Krause and Nakajima, 2015) [7].

The fourth and final stage of the menopausal process is known as post-menopause. The term "post-menopause" refers to the period following menopause. A woman is technically postmenopausal from the time menopause begins until the end of her life. Most women's menopausal symptoms, such as hot flashes, can subside at this time (Santoro and Randolph, 2011) [2]. The same hormonal changes and external circumstances that create the other stages of menopause also cause postmenopause (Souza, 2013) [8].

Urea, also known as carbamide, is a nitrogen-containing chemical molecule that plays a significant role in animal nitrogen metabolism and is the predominant nitrogen-containing substance in mammalian urine (Crawford, 2005). When measured in the blood, urea is referred to as blood urea nitrogen (BUN). Urea is a byproduct of protein metabolism. Protein consumption, the body's ability to catabolize protein, and appropriate urea excretion via the renal system all influence urea concentration (Decaux, 2010) [9].

Creatinine is created when creatine and phosphor-creatine are broken down, and it can be used to assess renal function. The amino acids arginine, glycine, and methionine are transaminated in the liver, pancreas, and kidneys to produce creatine (Crawford, 2005) [10]. Because serum creatinine is an easily measurable indicator of muscle metabolism that is eliminated unchanged predominantly by the kidneys, mostly through glomerular filtration, but also by proximal tubular secretion, it is an essential indicator of renal health (Shemesh et al., 2008) [11]. The estimated GFR (eGFR) can also be calculated solely based on serum creatinine levels (Hayashi, 2009) [12].

The glomerulus' filtration capability is demonstrated by measuring creatinine concentrations in plasma and urine samples (Raforth and Onstad, 1995) [13]. Although less specific than creatinine, urea can be used to assess renal function (Narayanan and Appleton, 2008) [14]. The onset of moderate renal impairment has been linked to growing older (Seliger et al., 2004) [15]. In Ekpoma, however, there is a smattering of literature on the assessment of renal function in pre- and post-menopausal women. Furthermore, the importance of maintaining middle-aged women's health cannot be overstated, since bad health might influence their job experience and longevity. The need for pre- and post-menopausal women to constantly monitor some renal function parameters such as urea and creatinine which are important marker for detecting renal dysfunction cannot be overemphasized. This study was therefore carried out to determine the urea and creatinine levels of premenopausal and postmenopausal women in Ekpoma, Edo State, Nigeria.