Tamm-Horsfall-Protein, ? 1- und ? 2-Mikroglobulin als Nierenfunktionsmarker in der Herzchirurgie

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Abstract
Operationen am offenen Herzen gehen in bis zu 4% der Fälle mit zeitweiligen Nierenfunktionsstörungen einher. Eine Lokalisation der Schädigung ist nur invasiv mit der Feinnadelbiopsie möglich. Die Ausscheidung des Nierentubulusproteins Tamm-Horsfall (THP) und der Mikroglobuline α-1 (α-1 MG) und β-2 (β-2 MG) wurden bei insgesamt 30 Patienten untersucht. Eine Einteilung in 2 Gruppen erfolgte nach der präoperativen Kreatinin-Clearance (Cl Krea ). Alle Patienten wurden vor und bis zum 2. Tag postoperativ beobachtet. Die Gruppe der präoperativ Nierengesunden umfaßte 15 Patienten (13 m/2 w, Diagnosen: 14mal ACB, 3mal Klappenersatz). Das THP zeigte einen gleichbleibenden Verlauf mit einer Korrelation von 0,7 zur Cl Krea (p p Krea verhielt sich auch in dieser Gruppe der Verlauf des THP. α-1- und β-2-MG stiegen von 32,8 (0,73) mg als leicht pathologische Werte als Zeichen einer massiven tubulären Schädigung postoperativ stark an. Hier konnte gezeigt werden, daß Operationen am offenen Herzen häufig transiente Nierenfunktionsstörungen verursachen, besonders bei vorbestehenden Schäden. Außerdem wurde gezeigt, daß mit empfindlichen Parametern tubuläre und glomeruläre Schäden verifiziert werden können. After cardiac surgery, transient renal dysfunction often occurs. Regional differentiation of these processes is possible only using invasive techniques, including renal biopsy. Approximately 30 different plasma protein components have been identified in the urine of healthy individuals by means of qualitative and quantitative immunochemical methods. The detection of microalbuminuria has high diagnostic relevance for the early diagnosis of renal damage at a reversible stage. One typical urinary protein is Tamm-Horsfall protein (THp). After histochemical staining of human kidney sections, activity is seen in the loop of Henle and initial distal tubule. The assay of α-1 microglobulin (MG) in urine is considered one of the most efficient laboratory parameters for the diagnosis of tubular lesions. Serum concentrations of α-1 MG are less dependent on extrarenal changes than are those of other low-molecular-weight proteins. β-2 MG is also one of the standards used in recent years for diagnostic relevance. Urinary albumin excretion, normaly less than 30 mg per day, sometimes increases after glomerular damage. Some renal function tests are used daily in many intensive care units, e.g. creatinine clearance (CCr) or urea and sodium excretion. Renal dysfunction should, however, be further examined to localise regional damage and to seek new clinical standards in addition to the conventional tests. Methods. After obtaining the agreement of the local ethics committee, 30 patients were divided into two groups of 15 each: group I without renal dysfunction and CCr more than 60 ml/min; and group II with CCr below 60 ml/min. THp and α-1 MG were measured pre- and postoperatively after open heart surgery with the ELISA and β-2 MG with the nephelometric technique. These parameters were compared with clinical standards such as albumin excretion, blood urea nitrogen (BUN), urea clearance, and fractional sodium excretion. Results. The CCr did not change in group I from the pre- to postoperative period (81.5 to 85.1 and 91.4 ml/min), nor did excretion of THp (20.1 to 25.0 and 24.8 mg/day), correlation r=0.7; PDiscussion. Measurement of the excretion of THp and α-1 and β-2 MG is a useful addition to present clinical standards for recognising early changes in renal function. The increases in the postoperative period after cardiac surgery showed tubular damage even in patients without predictive risk factors or clinical signs. In patients with renal dysfunction open heart surgery and extracorporeal circulation led to significant tubular damage.

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