GREM1 and systemic lupus erythematosus: Urinary Gremlin levels were significantly higher in ANCA CGN (n = 20, 354 ± 76 ug/gCr) than those found in non-ANCA CGN in SLE (n = 17) and in IgA nephropathy (n = 3) that were 95.1 ± 15.2 ug/gCr).