Table 29. Criteria for the diagnosis and classification of relapses of LN.

Mild kidney relapse	Moderate kidney relapse	Severe kidney relapse
Increase in glomerular hematuria from <5 to >15 RBC/hpf, with ≥2 acanthocytes/hpf	If baseline creatinine is:	If baseline creatinine is:
and/or	<2.0 mg/dl [<177 μmol/l], an increase of 0.20–1.0 mg/dl [17.7–88.4 μmol/l]	<2 mg/dl [<177 μmol/l], an increase of >1.0 mg/dl [>88.4 μmol/l]
recurrence of ≥1 RBC cast, WBC cast (no infection), or both	⩾2.0 mg/dl [⩾177 μmol/l], an increase of 0.40–1.5 mg/dl [35.4–132.6 μmol/l]	⩾2 mg/dl [⩾177 μmol/l], an increase of >1.5 mg/dl [>132.6 μmol/l]
	and/or	and/or
	If baseline uPCR is:
	<500 mg/g [<50 mg/mmol], an increase to ⩾1000 mg/g [⩾100 mg/mmol]	an absolute increase of uPCR >5000 mg/g [>500 mg/mmol]
	500–1000 mg/g [50–100 mg/mmol], an increase to ⩾2000 mg/g [⩾200 mg/mmol], but less than absolute increase of <5000 mg/g [<500 mg/mmol]
	>1000 mg/g [>100 mg/mmol], an increase of ⩾2-fold with absolute uPCR <5000 mg/g [<500 mg/mmol]

hpf, high-power field; LN, lupus nephritis; RBC, red blood cell; uPCR, urine protein:creatinine ratio; WBC, white blood cell.

Adapted from Lahita RG, Tsokos GT, Buyon JP, Koike T (eds). Systemic Lupus Erythematosus, 5th edn. Rovin BH, Stillman IE. Chapter 42: Kidney. Elsevier: Waltham, MA, 2011, pp 769–814 with permission from Elsevier.⁶⁸⁷