Moledina et al reported a model for the diagnosis of acute interstitial nephritis. The authors are from Yale University, Indiana University, Arkansas Laboratories (Little Rock), and Johns Hopkins University.
Parameters:
(1) serum creatinine in mg/dL
(2) serum blood urea nitrogen (BUN) in mg/dL
(3) urine dipstick specific gravity
(4) urine dipstick protein
BUN to creatiinine ratio =
= (BUN) / (serum creatinine)
Parameter
Finding
Points
serum creatinine
0.8367518 * LN(creatinine)
BUN to creatinine ratio
-0.9181938 * LN(ratio)
urine specific gravity
-0.0501203 * (specific gravity)
urine dipstick protein
0, trace, 1+
0.9360127
2+ or 3+
0
value of X =
= SUM(points for all of the parameters) - 0.770398
probability of interstitial nephritis =
= 1 / ( 1 + EXP((-1) * X))
Performance:
• The area under the ROC curve was 0.73.
• Addition of biomarkers (urine IL-9, TNF-alpha) improved AUROC to 0.84.
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