Liver‐type fatty acid‐binding protein and neutrophil gelatinase‐associated lipocalin in cats with chronic kidney disease and hyperthyroidism

Abstract

Background: Liver-type fatty acid-binding protein (L-FABP) and neutrophil gelatinase-associated lipocalin (NGAL) are candidate biomarkers for the detection of early chronic kidney disease (CKD) in cats.Objective: To evaluate urinary and serum L-FABP and NGAL concentrations in CKD cats and in hyperthyroid cats before and after radioiodine ( 131 I) treatment.Animals: Nine CKD cats, 45 healthy cats and hyperthyroid cats at 3 time points including before (T0, n = 49), 1 month (T1, n = 49), and 11 to 29 months after (T2, n = 26) 131 I treatment.Methods: Cross-sectional and longitudinal study. Serum L-FABP (sL-FABP), serum NGAL (sNGAL), urinary L-FABP (uL-FABP), and urinary NGAL (uNGAL) were compared between the 3 groups and between hyperthyroid cats before and after treatment. Data are reported as median (min-max).Results: CKD cats had significantly higher sL-FABP (13.50 [3.40-75.60] ng/ml) and uL-FABP/Cr (4. 90 [0.97-2139.44] μg/g) than healthy cats (4. 25 [1.34-23.25] ng/ml;

Renal biomarkers in cats: A review of the current status in chronic kidney disease

“…It is only known that uL‐FABP/Cr is significantly increased in hyperthyroid cats, and resolved after euthyroidism was established. 91 It remains unknown whether uL‐FABP concentration can predict post‐treatment azotemia in hyperthyroid cats because of a low number of post‐treatment azotemic cats in this study. 91 …”

“… 91 It remains unknown whether uL‐FABP concentration can predict post‐treatment azotemia in hyperthyroid cats because of a low number of post‐treatment azotemic cats in this study. 91 …”

“…The reason for the discordant findings between these studies is unclear, but might be because of the different assays used. 91 The former study also assessed the prognostic utility of uNGAL concentrations in CKD cats and found higher baseline uNGAL/Cr concentrations in the group with progression compared to the group without progression. 94 Unfortunately, this finding must be interpreted cautiously because of important study limitations such as the different severity of azotemia between both groups at baseline and the short duration of follow‐up (30 days).…”

“… 94 Circulating NGAL concentrations do not affect uNGAL concentrations in cats. 91 , 94 Urinary tract infections (UTI) and pyuria increase uNGAL concentrations in both dogs and cats. 95 , 131 Therefore, lower urinary tract disease or UTI should be ruled out before interpreting uNGAL concentration as a biomarker of renal disease in these species.…”

“… 91 , 92 , 93 It was detected in the cytoplasm of proximal tubular cells in healthy feline kidneys using immunohistochemistry with antibodies targeting human L‐FABP, and it was expressed in the tubular lumen in response to ischemic‐reperfusion injury. 92 Most healthy control cats had uL‐FABP/Cr ratios below the limit of detection, 91 , 92 whereas this ratio increased in an AKI model in cats immediately after inducing ischemic‐reperfusion injury. 92 Although uL‐FABP/Cr was significantly increased in CKD cats compared to healthy cats, an overlap between groups was noted.…”