Neutrophil gelatinase-associated lipocalin and fibrinogen-to-albumin ratio are indicators of kidney disease in sickle cell disease patients with microalbuminuria: a multicentre case-control study in Ghana

Neutrophil gelatinase-associated lipocalin (NGAL) is present in secondary granules of neutrophils and it is a relatively newly recognized marker of kidney diseases. The fibrinogen-to-albumin ratio (FAR) is a marker of inflammation but its diagnostic value has not been determined in sickle cell disease patients with kidney diseases. This study investigated the diagnostic roles of serum neutrophil gelatinase-associated lipocalin (sNGAL) and FAR for kidney diseases in steady-state adult sickle cell disease (SCD) patients. This study employed a prospective case-control design and recruited 104 SCD participants and 80 non-SCD patients. Participants' information was thoroughly documented using a structured questionnaire and patient case records. To evaluate the hematobiochemical parameters, 5 ml of venous blood was drawn from each participant and a clean catch of midstream urine was collected from each participant. The cases and controls were further categorized into microalbuminuria and non-microalbuminuria subjects, following three consecutive urine albumin-to-creatinine ratio (UACR) measurements. The prevalence of microalbuminuria was 32.7% among adult steady-state SCD patients. Significant higher levels of sNGAL and FAR were detected in SCD patients with microalbuminuria than in SCD patients without microalbuminuria and controls (p < 0.001). A moderate positive correlation was observed between sNGAL and UACR (r = 0.45, p = 0.007). A unit increase in sNGAL (cOR: 3.25 (2.11-5.00); p < 0.001), aOR: 3.35(2.09-5.36); p < 0.0001)) and FAR (Log cOR: 12.26 (1.82-25.09); p = 0.022) were significantly associated with increased odds of kidney disease among SCD participants. sNGAL emerged as a highly early predictive marker for kidney disease in SCD patients, with a cutoff value of > 5.72 µg/L yielding a high area under the curve (AUC = 0.854, p < 0.0001). sNGAL also demonstrated an excellent sensitivity (91.2%) and moderate specificity (74.7%). The FAR at a cutoff of > 0.09 also demonstrated significant predictive value (AUC = 0.630, p = 0.009) for kidney disease in SCD patients, with a moderate sensitivity (67.6%) and specificity (61.3%). Based on our findings, sNGAL could serve as an independent early predictor of kidney disease compared with urea and creatinine. Additionally, the fibrinogen-to-albumin ratio can be used as inflammatory marker for kidney diseases in SCD patients. Not applicable.