Fractional Excretion of Beta-2-Microglobulin in the Urine of Patients with Normal or Reduced Renal Function and Hepatic Coma

Abstract

The purpose of this prospective study was to evaluate beta-2-microglobulin (β²m) as a differential diagnostic indicator between hepatic nephropathy (HN) and acute tubulointerstitial nephropathy (ATIN) in patients with reduced renal function and hepatic coma, and to determine whether β₂m excretion could be used as a marker of renal impairment before increased serum creatinine (S-Cr) concentration or decreased creatinine clearance (Cr-Cl). Finally, the use of β₂m as a prognostic indicator was investigated. Eighteen patients in hepatic coma grade III-IV were entered in the study and were divided into two groups in accordance with their renal function (serum creatinine above/below 180 μmol/l). The fractional excretion of β₂m (FE-β₂m) was used to monitor β₂m elimination. The study failed to show any distinction in FE-β₂m between HN and ATIN patients, presumably owing to the small number of patients. FE-β₂m could not predict the development of renal failure earlier than the increase in S-Cr or decrease in Cr-Cl. However, a few patients who survived paracetamol intoxication had increased FE-β₂M in the beginning of the coma and normal S-Cr and Cr-Cl. Patients who died as a result of paracetamol intoxication had both abnormal FE-β₂m and abnormal S-Cr and Cr-Cl, suggesting that if therapy had been initiated earlier, when only FE-β₂m was affected, these patients might have survived. All patients who survived, except three paracetamol-and one aminoglycoside-intoxicated patient, had normal FE-β₂m in the beginning of the coma. This indicates that β₂m is of prognostic value, especially in patients with non-drug-related hepatopathy.

Key Words:

• Acute tubulointerstitial nephropathy
• beta-2-microglobulin
• hepatic coma
• hepatorenal failure