Marked enzymuria after bone marrow transplantation

During the first month after bone marrow transplantation, approximately 15% of patients develop acute renal failure (ARF). This usually occurs in the setting of hepatic veno-occlusive disease (VOD). Prior clinical data have suggested that this form of ARF has a hemodynamic basis, analogous to the hepatorenal syndrome (HRS). If so, then proximal tubular injury would not be expected. To directly test this hypothesis, enzymuria (N-acetyl-beta-D-glucosaminidase [NAG]) was quantitated in the following groups of patients within the first 35 days after BMT: (1) VOD+ARF (serum creatinine level > 1.5 mg/dL; N = 10); (2) VOD with relatively normal renal function (serum creatinine level < 1.5 mg/dL; N = 11); and (3) patients without hepatic or renal complications (BMT controls; N = 12). For comparison, NAG was also quantitated in the following groups of non-BMT patients: (1) toxic/ischemic acute tubular necrosis (ATN) (N = 10); (2) jaundice without azotemia (N = 5); and (3) HRS (N = 6). Urine samples from eight healthy subjects established normal NAG concentrations (2.5 +/- 0.5 microU/mg urinary creatinine; mean +/- SE). All non-BMT patients with ATN had markedly elevated NAG levels (61 +/- 12; P < 0.001), validating the test as a marker of tubular damage. NAG concentrations were significantly elevated in all of the control BMT patients (24 +/- 3; P < 0.01), and the presence of VOD was associated with further striking increments (approximately 50 times normal). However, the degree of enzymuria was virtually identical for VOD patients with (125 +/- 27) and without (122 +/- 17) ARF. Jaundice in a non-BMT setting was associated with only mild NAG elevations (11 +/- 2). However, striking enzymuria was noted in all HRS patients (61 +/- 20), equaling the levels seen with ATN. The following conclusions were derived: (1) subclinical tubular injury, as defined by enzymuria, appears to be ubiquitous after BMT; (2) VOD dramatically increases the extent of enzymuria; (3) the degree of enzymuria in VOD patients is not correlated with renal dysfunction, implying that the associated ARF has a large hemodynamic component; and (4) HRS and ATN manifest comparable degrees of enzymuria, suggesting that substantial tubular damage exists in both of these forms of ARF.