Reference intervals for serum cystatin C and serum creatinine in an adult sub-Saharan African population

Abstract

BackgroundSerum cystatin C (SCysC) and serum creatinine (SCr) are two biomarkers used in common practice to estimate the glomerular filtration rate (GFR). For SCysC and SCr to be used in a given population, normal values need to be determined to better assess patients. This study aimed to determine SCysC and SCr reference intervals (RIs) in a Cameroonian adult population and factors susceptible of influencing them.MethodsWe carried-out a cross-sectional study from November 2016 to May 2017 in Yaoundé, Cameroon. Participants were Cameroonians aged 18 years and above, residing inside the country and found in good health at study inclusion. SCysC and SCr were determined by particle-enhanced turbidimetric immunoassay standardized against the ERM-DA471/IFCC reference material and by the IDMS reference modified Jaffe kinetic method, respectively. RIs were determined using the 2.5th and 97.5th percentiles and their respective 90% confidence intervals (CIs). The quantile regression served to identify potential factors likely influencing SCysC and SCr values.ResultsWe included 381 subjects comprising 49.1% females.. RIs for SCysC varied between 0.57 (90%CI: 0.50–0.60) and 1.03 mg/L (90%CI: 1.00–1.10) for females, and from 0.70 (90%CI: 0.60–0.70) to 1.10 mg/L (90%CI: 1.10–1.20) for males. Concerning SCr, its RIs ranged from 0.58 (90%CI: 0.54–0.61) to 1.08 mg/dL (90%CI: 1.02–1.21) for females, and from 0.74 (90%CI: 0.70–0.80) to 1.36 mg/dL (90%CI: 1.30–1.45) for males. Men had significantly higher SCysC and SCr values than women (p < 0.001). Likewise, subjects aged 50 years and above had higher SCysC values in comparison to younger age groups (p < 0.001), which was not the case for SCr values (p = 0.491). Moreover, there was a positive and significant correlation between SCysC and SCr in women (ρ = 0.55, p < 0.001), in men (ρ = 0.39, p < 0.001) and globally (ρ = 0.58; p < 0.001). Furthermore, the sex influenced both biomarkers’ values across all quantile regression models while age and body surface area (BSA) influenced them inconsistently.ConclusionThis study has determined serum cystatin C and serum creatinine reference intervals in an adult Cameroonian population, whose interpretations might take into account the patient’s sex and to a certain extent, his/her age and/or BSA.Electronic supplementary materialThe online version of this article (10.1186/s12907-019-0086-7) contains supplementary material, which is available to authorized users.

Serum Cystatin C Reference Interval and Derived Estimated Glomerular Filtration Rate Values in Healthy Adult Zimbabwean Blood Donors

“…Generally, these intervals are higher than those obtained in the present study. Men had significantly higher levels than females and this was in concordance with findings from the present study [21].…”

Analysis of renal function in a Health Examination Population in Chengdu (2012-2018)

“…When renal function is impaired, Cr products cannot be completely excreted, resulting in elevated serum Cr concentration [23]. Bertille et al reported increased levels of Cr and CysC in males when compared with those in females, and they were higher in subjects over 55 years old [24]. Similar to these ndings, increased Cr and CysC levels in males and the elderly population were also detected in our study.…”

Reply to comment on: Urinary sodium excretion and its association with blood pressure in Nigeria: A nationwide population survey

“…The CARDIA study enrolled blacks with incomplete African ancestry (averaged at 72.5%) and high socio‐economic status (where more than 65% earn over 25 000 dollars per annum). Similarly, in contrast to our study, other two studies among native Africans included individuals living in the urban cities of Kinshasa 6 or Yaounde, 8 majority of whom are young people. Expectedly, serum/urine creatinine should be higher among these populations given their higher socio‐economic status and lower average age.…”

“… 6 We are convinced that the poor nutrition status of individuals residing in both rural and urban areas included in our study was responsible for this. Although Khitan and colleagues have argued otherwise by referring to one study conducted among African Americans in the USA 7 and two other studies 6 , 8 conducted among Blacks living in Africa. They opined that since African Americans enrolled in the CARDIA study had higher level of serum creatinine compared to their European counterparts, 7 urinary creatinine of our population should be higher than reported.…”